]> git.saurik.com Git - apple/xnu.git/blobdiff - osfmk/kern/sched_prim.c
xnu-3247.1.106.tar.gz
[apple/xnu.git] / osfmk / kern / sched_prim.c
index d7b959249aabd874f45413858fbcd9df123ee79c..9a0a9427cdf7af516c2b64a53482e6617e1c1127 100644 (file)
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2009 Apple Inc. All rights reserved.
+ * Copyright (c) 2000-2012 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
@@ -65,9 +65,6 @@
  */
 
 #include <debug.h>
-#include <mach_kdb.h>
-
-#include <ddb/db_output.h>
 
 #include <mach/mach_types.h>
 #include <mach/machine.h>
 #include <machine/machine_cpu.h>
 #include <machine/machlimits.h>
 
+#ifdef CONFIG_MACH_APPROXIMATE_TIME
+#include <machine/commpage.h>
+#endif
+
 #include <kern/kern_types.h>
 #include <kern/clock.h>
 #include <kern/counters.h>
 #include <kern/cpu_number.h>
 #include <kern/cpu_data.h>
+#include <kern/smp.h>
 #include <kern/debug.h>
-#include <kern/lock.h>
 #include <kern/macro_help.h>
 #include <kern/machine.h>
 #include <kern/misc_protos.h>
 #include <kern/queue.h>
 #include <kern/sched.h>
 #include <kern/sched_prim.h>
+#include <kern/sfi.h>
 #include <kern/syscall_subr.h>
 #include <kern/task.h>
 #include <kern/thread.h>
-#include <kern/wait_queue.h>
+#include <kern/ledger.h>
+#include <kern/timer_queue.h>
+#include <kern/waitq.h>
 
 #include <vm/pmap.h>
 #include <vm/vm_kern.h>
 
 #include <kern/pms.h>
 
+#if defined(CONFIG_TELEMETRY) && defined(CONFIG_SCHED_TIMESHARE_CORE)
+#include <kern/telemetry.h>
+#endif
+
 struct rt_queue        rt_runq;
-#define RT_RUNQ                ((processor_t)-1)
-decl_simple_lock_data(static,rt_lock);
 
-#if defined(CONFIG_SCHED_TRADITIONAL) || defined(CONFIG_SCHED_PROTO) || defined(CONFIG_SCHED_GRRR) || defined(CONFIG_SCHED_FIXEDPRIORITY)
-static struct fairshare_queue  fs_runq;
-#define FS_RUNQ                ((processor_t)-2)
-decl_simple_lock_data(static,fs_lock);
+uintptr_t sched_thread_on_rt_queue = (uintptr_t)0xDEAFBEE0;
+
+/* Lock RT runq, must be done with interrupts disabled (under splsched()) */
+#if __SMP__
+decl_simple_lock_data(static,rt_lock);
+#define rt_lock_init()         simple_lock_init(&rt_lock, 0)
+#define rt_lock_lock()         simple_lock(&rt_lock)
+#define rt_lock_unlock()       simple_unlock(&rt_lock)
+#else
+#define rt_lock_init()         do { } while(0)
+#define rt_lock_lock()         do { } while(0)
+#define rt_lock_unlock()       do { } while(0)
 #endif
 
 #define                DEFAULT_PREEMPTION_RATE         100             /* (1/s) */
 int                    default_preemption_rate = DEFAULT_PREEMPTION_RATE;
 
+#define                DEFAULT_BG_PREEMPTION_RATE      400             /* (1/s) */
+int                    default_bg_preemption_rate = DEFAULT_BG_PREEMPTION_RATE;
+
 #define                MAX_UNSAFE_QUANTA                       800
 int                    max_unsafe_quanta = MAX_UNSAFE_QUANTA;
 
@@ -136,14 +153,16 @@ uint64_t  max_poll_computation;
 uint64_t       max_unsafe_computation;
 uint64_t       sched_safe_duration;
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
+#if defined(CONFIG_SCHED_TIMESHARE_CORE)
 
 uint32_t       std_quantum;
 uint32_t       min_std_quantum;
+uint32_t       bg_quantum;
 
 uint32_t       std_quantum_us;
+uint32_t       bg_quantum_us;
 
-#endif /* CONFIG_SCHED_TRADITIONAL */
+#endif /* CONFIG_SCHED_TIMESHARE_CORE */
 
 uint32_t       thread_depress_time;
 uint32_t       default_timeshare_computation;
@@ -152,74 +171,57 @@ uint32_t  default_timeshare_constraint;
 uint32_t       max_rt_quantum;
 uint32_t       min_rt_quantum;
 
-uint32_t       sched_cswtime;
-
-#if defined(CONFIG_SCHED_TRADITIONAL)
+#if defined(CONFIG_SCHED_TIMESHARE_CORE)
 
 unsigned       sched_tick;
 uint32_t       sched_tick_interval;
+#if defined(CONFIG_TELEMETRY)
+uint32_t       sched_telemetry_interval;
+#endif /* CONFIG_TELEMETRY */
 
 uint32_t       sched_pri_shift = INT8_MAX;
+uint32_t       sched_background_pri_shift = INT8_MAX;
+uint32_t       sched_combined_fgbg_pri_shift = INT8_MAX;
 uint32_t       sched_fixed_shift;
+uint32_t       sched_use_combined_fgbg_decay = 0;
 
-static boolean_t sched_traditional_use_pset_runqueue = FALSE;
+uint32_t       sched_decay_usage_age_factor = 1; /* accelerate 5/8^n usage aging */
 
-__attribute__((always_inline))
-static inline run_queue_t runq_for_processor(processor_t processor)
-{
-       if (sched_traditional_use_pset_runqueue)
-               return &processor->processor_set->pset_runq;
-       else
-               return &processor->runq;
-}
+/* Allow foreground to decay past default to resolve inversions */
+#define DEFAULT_DECAY_BAND_LIMIT ((BASEPRI_FOREGROUND - BASEPRI_DEFAULT) + 2)
+int            sched_pri_decay_band_limit = DEFAULT_DECAY_BAND_LIMIT;
 
-__attribute__((always_inline))
-static inline void runq_consider_incr_bound_count(processor_t processor, thread_t thread)
-{
-       if (thread->bound_processor == PROCESSOR_NULL)
-               return;
-    
-       assert(thread->bound_processor == processor);
-    
-       if (sched_traditional_use_pset_runqueue)
-               processor->processor_set->pset_runq_bound_count++;
-    
-       processor->runq_bound_count++;
-}
+/* Defaults for timer deadline profiling */
+#define TIMER_DEADLINE_TRACKING_BIN_1_DEFAULT 2000000 /* Timers with deadlines <=
+                                                       * 2ms */
+#define TIMER_DEADLINE_TRACKING_BIN_2_DEFAULT 5000000 /* Timers with deadlines
+                                                         <= 5ms */
 
-__attribute__((always_inline))
-static inline void runq_consider_decr_bound_count(processor_t processor, thread_t thread)
-{
-       if (thread->bound_processor == PROCESSOR_NULL)
-               return;
-    
-       assert(thread->bound_processor == processor);
-    
-       if (sched_traditional_use_pset_runqueue)
-               processor->processor_set->pset_runq_bound_count--;
-    
-       processor->runq_bound_count--;
-}
+uint64_t timer_deadline_tracking_bin_1;
+uint64_t timer_deadline_tracking_bin_2;
 
-#endif /* CONFIG_SCHED_TRADITIONAL */
+thread_t sched_maintenance_thread;
+
+#endif /* CONFIG_SCHED_TIMESHARE_CORE */
 
 uint64_t       sched_one_second_interval;
 
-uint32_t       sched_run_count, sched_share_count;
+uint32_t       sched_run_count, sched_share_count, sched_background_count;
 uint32_t       sched_load_average, sched_mach_factor;
 
 /* Forwards */
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
+#if defined(CONFIG_SCHED_TIMESHARE_CORE)
 
-static void load_shift_init(void) __attribute__((section("__TEXT, initcode")));
-static void preempt_pri_init(void) __attribute__((section("__TEXT, initcode")));
+static void load_shift_init(void);
+static void preempt_pri_init(void);
 
-#endif /* CONFIG_SCHED_TRADITIONAL */
+#endif /* CONFIG_SCHED_TIMESHARE_CORE */
 
 static thread_t        thread_select(
                                        thread_t                        thread,
-                                       processor_t                     processor);
+                                       processor_t                     processor,
+                                       ast_t                           reason);
 
 #if CONFIG_SCHED_IDLE_IN_PLACE
 static thread_t        thread_select_idle(
@@ -231,102 +233,24 @@ thread_t processor_idle(
                                        thread_t                        thread,
                                        processor_t                     processor);
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
-
-static thread_t        steal_thread(
-                                       processor_set_t         pset);
-
-static thread_t        steal_thread_disabled(
-                                       processor_set_t         pset) __attribute__((unused));
-
-
-static thread_t        steal_processor_thread(
-                                       processor_t                     processor);
-
-static void            thread_update_scan(void);
+ast_t
+csw_check_locked(      processor_t             processor,
+                                       processor_set_t pset,
+                                       ast_t                   check_reason);
 
 static void processor_setrun(
                                 processor_t                    processor,
                                 thread_t                       thread,
                                 integer_t                      options);
 
-static boolean_t
-processor_enqueue(
-                                 processor_t           processor,
-                                 thread_t              thread,
-                                 integer_t             options);
-
-static boolean_t
-processor_queue_remove(
-                                          processor_t                  processor,
-                                          thread_t             thread);
-
-static boolean_t       processor_queue_empty(processor_t               processor);
-
-static boolean_t       priority_is_urgent(int priority);
-
-static ast_t           processor_csw_check(processor_t processor);
-
-static boolean_t       processor_queue_has_priority(processor_t                processor,
-                                                                                       int                             priority,
-                                                                                       boolean_t               gte);
-
-static boolean_t       should_current_thread_rechoose_processor(processor_t                    processor);
-
-static int     sched_traditional_processor_runq_count(processor_t   processor);
-
-static boolean_t       sched_traditional_with_pset_runqueue_processor_queue_empty(processor_t          processor);
-
-static uint64_t     sched_traditional_processor_runq_stats_count_sum(processor_t   processor);
-
-static uint64_t                sched_traditional_with_pset_runqueue_processor_runq_stats_count_sum(processor_t   processor);
-#endif
-       
-
-#if defined(CONFIG_SCHED_TRADITIONAL)
-
-static void
-sched_traditional_init(void);
-
-static void
-sched_traditional_timebase_init(void);
-
-static void
-sched_traditional_processor_init(processor_t processor);
-
 static void
-sched_traditional_pset_init(processor_set_t pset);
-
-static void
-sched_traditional_with_pset_runqueue_init(void);
-
-#endif
-
-static void
-sched_realtime_init(void)  __attribute__((section("__TEXT, initcode")));
+sched_realtime_init(void);
 
 static void
 sched_realtime_timebase_init(void);
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
 static void
-sched_traditional_tick_continue(void);
-
-static uint32_t
-sched_traditional_initial_quantum_size(thread_t thread);
-
-static sched_mode_t
-sched_traditional_initial_thread_sched_mode(task_t parent_task);
-
-static boolean_t
-sched_traditional_supports_timeshare_mode(void);
-
-static thread_t
-sched_traditional_choose_thread(
-                                                               processor_t             processor,
-                                                               int                             priority);
-
-#endif
+sched_timer_deadline_tracking_init(void);
 
 #if    DEBUG
 extern int debug_task;
@@ -335,120 +259,18 @@ extern int debug_task;
 #define TLOG(a, fmt, args...) do {} while (0)
 #endif
 
-#if    DEBUG
-static
-boolean_t      thread_runnable(
-                               thread_t                thread);
-
-#endif /*DEBUG*/
+static processor_t
+thread_bind_internal(
+       thread_t                thread,
+       processor_t             processor);
 
-/*
- *     State machine
- *
- * states are combinations of:
- *  R  running
- *  W  waiting (or on wait queue)
- *  N  non-interruptible
- *  O  swapped out
- *  I  being swapped in
- *
- * init        action 
- *     assert_wait thread_block    clear_wait          swapout swapin
- *
- * R   RW, RWN     R;   setrun     -                   -
- * RN  RWN         RN;  setrun     -                   -
- *
- * RW              W               R                   -
- * RWN             WN              RN                  -
- *
- * W                               R;   setrun         WO
- * WN                              RN;  setrun         -
- *
- * RO                              -                   -       R
- *
- */
+static void
+sched_vm_group_maintenance(void);
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
+#if defined(CONFIG_SCHED_TIMESHARE_CORE)
 int8_t         sched_load_shifts[NRQS];
 int            sched_preempt_pri[NRQBM];
-#endif
-
-
-#if defined(CONFIG_SCHED_TRADITIONAL)
-
-const struct sched_dispatch_table sched_traditional_dispatch = {
-       sched_traditional_init,
-       sched_traditional_timebase_init,
-       sched_traditional_processor_init,
-       sched_traditional_pset_init,
-       sched_traditional_tick_continue,
-       sched_traditional_choose_thread,
-       steal_thread,
-       compute_priority,
-       choose_processor,
-       processor_enqueue,
-       processor_queue_shutdown,
-       processor_queue_remove,
-       processor_queue_empty,
-       priority_is_urgent,
-       processor_csw_check,
-       processor_queue_has_priority,
-       sched_traditional_initial_quantum_size,
-       sched_traditional_initial_thread_sched_mode,
-       sched_traditional_supports_timeshare_mode,
-       can_update_priority,
-       update_priority,
-       lightweight_update_priority,
-       sched_traditional_quantum_expire,
-       should_current_thread_rechoose_processor,
-       sched_traditional_processor_runq_count,
-       sched_traditional_processor_runq_stats_count_sum,
-       sched_traditional_fairshare_init,
-       sched_traditional_fairshare_runq_count,
-       sched_traditional_fairshare_runq_stats_count_sum,
-       sched_traditional_fairshare_enqueue,
-       sched_traditional_fairshare_dequeue,
-       sched_traditional_fairshare_queue_remove,
-       TRUE /* direct_dispatch_to_idle_processors */
-};
-
-const struct sched_dispatch_table sched_traditional_with_pset_runqueue_dispatch = {
-       sched_traditional_with_pset_runqueue_init,
-       sched_traditional_timebase_init,
-       sched_traditional_processor_init,
-       sched_traditional_pset_init,
-       sched_traditional_tick_continue,
-       sched_traditional_choose_thread,
-       steal_thread,
-       compute_priority,
-       choose_processor,
-       processor_enqueue,
-       processor_queue_shutdown,
-       processor_queue_remove,
-       sched_traditional_with_pset_runqueue_processor_queue_empty,
-       priority_is_urgent,
-       processor_csw_check,
-       processor_queue_has_priority,
-       sched_traditional_initial_quantum_size,
-       sched_traditional_initial_thread_sched_mode,
-       sched_traditional_supports_timeshare_mode,
-       can_update_priority,
-       update_priority,
-       lightweight_update_priority,
-       sched_traditional_quantum_expire,
-       should_current_thread_rechoose_processor,
-       sched_traditional_processor_runq_count,
-       sched_traditional_with_pset_runqueue_processor_runq_stats_count_sum,
-       sched_traditional_fairshare_init,
-       sched_traditional_fairshare_runq_count,
-       sched_traditional_fairshare_runq_stats_count_sum,
-       sched_traditional_fairshare_enqueue,
-       sched_traditional_fairshare_dequeue,
-       sched_traditional_fairshare_queue_remove,
-       FALSE /* direct_dispatch_to_idle_processors */
-};
-
-#endif
+#endif /* CONFIG_SCHED_TIMESHARE_CORE */
 
 const struct sched_dispatch_table *sched_current_dispatch = NULL;
 
@@ -469,10 +291,12 @@ const struct sched_dispatch_table *sched_current_dispatch = NULL;
  * can run on multiple devices with different schedulers configured
  * in the device tree.
  */
-#define SCHED_STRING_MAX_LENGTH (48)
-
 char sched_string[SCHED_STRING_MAX_LENGTH];
-static enum sched_enum _sched_enum = sched_enum_unknown;
+
+uint32_t sched_debug_flags;
+
+/* Global flag which indicates whether Background Stepper Context is enabled */
+static int cpu_throttle_enabled = 1;
 
 void
 sched_init(void)
@@ -488,81 +312,78 @@ sched_init(void)
                }
        }
 
+       
+       if (!PE_parse_boot_argn("sched_pri_decay_limit", &sched_pri_decay_band_limit, sizeof(sched_pri_decay_band_limit))) {
+               /* No boot-args, check in device tree */
+               if (!PE_get_default("kern.sched_pri_decay_limit",
+                                                       &sched_pri_decay_band_limit,
+                                                       sizeof(sched_pri_decay_band_limit))) {
+                       /* Allow decay all the way to normal limits */
+                       sched_pri_decay_band_limit = DEFAULT_DECAY_BAND_LIMIT;
+               }
+       }
+
+       kprintf("Setting scheduler priority decay band limit %d\n", sched_pri_decay_band_limit);
+
        if (strlen(sched_arg) > 0) {
                if (0) {
                        /* Allow pattern below */
 #if defined(CONFIG_SCHED_TRADITIONAL)
-               } else if (0 == strcmp(sched_arg, kSchedTraditionalString)) {
+               } else if (0 == strcmp(sched_arg, sched_traditional_dispatch.sched_name)) {
                        sched_current_dispatch = &sched_traditional_dispatch;
-                       _sched_enum = sched_enum_traditional;
-                       strlcpy(sched_string, kSchedTraditionalString, sizeof(sched_string));
-                       kprintf("Scheduler: Runtime selection of %s\n", kSchedTraditionalString);
-               } else if (0 == strcmp(sched_arg, kSchedTraditionalWithPsetRunqueueString)) {
+               } else if (0 == strcmp(sched_arg, sched_traditional_with_pset_runqueue_dispatch.sched_name)) {
                        sched_current_dispatch = &sched_traditional_with_pset_runqueue_dispatch;
-                       _sched_enum = sched_enum_traditional_with_pset_runqueue;
-                       strlcpy(sched_string, kSchedTraditionalWithPsetRunqueueString, sizeof(sched_string));
-                       kprintf("Scheduler: Runtime selection of %s\n", kSchedTraditionalWithPsetRunqueueString);
 #endif
 #if defined(CONFIG_SCHED_PROTO)
-               } else if (0 == strcmp(sched_arg, kSchedProtoString)) {
+               } else if (0 == strcmp(sched_arg, sched_proto_dispatch.sched_name)) {
                        sched_current_dispatch = &sched_proto_dispatch;
-                       _sched_enum = sched_enum_proto;
-                       strlcpy(sched_string, kSchedProtoString, sizeof(sched_string));
-                       kprintf("Scheduler: Runtime selection of %s\n", kSchedProtoString);
 #endif
 #if defined(CONFIG_SCHED_GRRR)
-               } else if (0 == strcmp(sched_arg, kSchedGRRRString)) {
+               } else if (0 == strcmp(sched_arg, sched_grrr_dispatch.sched_name)) {
                        sched_current_dispatch = &sched_grrr_dispatch;
-                       _sched_enum = sched_enum_grrr;
-                       strlcpy(sched_string, kSchedGRRRString, sizeof(sched_string));
-                       kprintf("Scheduler: Runtime selection of %s\n", kSchedGRRRString);
 #endif
-#if defined(CONFIG_SCHED_FIXEDPRIORITY)
-               } else if (0 == strcmp(sched_arg, kSchedFixedPriorityString)) {
-                       sched_current_dispatch = &sched_fixedpriority_dispatch;
-                       _sched_enum = sched_enum_fixedpriority;
-                       strlcpy(sched_string, kSchedFixedPriorityString, sizeof(sched_string));
-                       kprintf("Scheduler: Runtime selection of %s\n", kSchedFixedPriorityString);
-               } else if (0 == strcmp(sched_arg, kSchedFixedPriorityWithPsetRunqueueString)) {
-                       sched_current_dispatch = &sched_fixedpriority_with_pset_runqueue_dispatch;
-                       _sched_enum = sched_enum_fixedpriority_with_pset_runqueue;
-                       strlcpy(sched_string, kSchedFixedPriorityWithPsetRunqueueString, sizeof(sched_string));
-                       kprintf("Scheduler: Runtime selection of %s\n", kSchedFixedPriorityWithPsetRunqueueString);
+#if defined(CONFIG_SCHED_MULTIQ)
+               } else if (0 == strcmp(sched_arg, sched_multiq_dispatch.sched_name)) {
+                       sched_current_dispatch = &sched_multiq_dispatch;
+               } else if (0 == strcmp(sched_arg, sched_dualq_dispatch.sched_name)) {
+                       sched_current_dispatch = &sched_dualq_dispatch;
 #endif
                } else {
+#if defined(CONFIG_SCHED_TRADITIONAL)
+                       printf("Unrecognized scheduler algorithm: %s\n", sched_arg);
+                       printf("Scheduler: Using instead: %s\n", sched_traditional_with_pset_runqueue_dispatch.sched_name);
+                       sched_current_dispatch = &sched_traditional_with_pset_runqueue_dispatch;
+#else
                        panic("Unrecognized scheduler algorithm: %s", sched_arg);
+#endif
                }
+               kprintf("Scheduler: Runtime selection of %s\n", SCHED(sched_name));
        } else {
-#if   defined(CONFIG_SCHED_TRADITIONAL)
-               sched_current_dispatch = &sched_traditional_dispatch;
-               _sched_enum = sched_enum_traditional;
-               strlcpy(sched_string, kSchedTraditionalString, sizeof(sched_string));
-               kprintf("Scheduler: Default of %s\n", kSchedTraditionalString);
+#if   defined(CONFIG_SCHED_MULTIQ)
+               sched_current_dispatch = &sched_multiq_dispatch;
+#elif defined(CONFIG_SCHED_TRADITIONAL)
+               sched_current_dispatch = &sched_traditional_with_pset_runqueue_dispatch;
 #elif defined(CONFIG_SCHED_PROTO)
                sched_current_dispatch = &sched_proto_dispatch;
-               _sched_enum = sched_enum_proto;
-               strlcpy(sched_string, kSchedProtoString, sizeof(sched_string));
-               kprintf("Scheduler: Default of %s\n", kSchedProtoString);
 #elif defined(CONFIG_SCHED_GRRR)
                sched_current_dispatch = &sched_grrr_dispatch;
-               _sched_enum = sched_enum_grrr;
-               strlcpy(sched_string, kSchedGRRRString, sizeof(sched_string));
-               kprintf("Scheduler: Default of %s\n", kSchedGRRRString);
-#elif defined(CONFIG_SCHED_FIXEDPRIORITY)
-               sched_current_dispatch = &sched_fixedpriority_dispatch;
-               _sched_enum = sched_enum_fixedpriority;
-               strlcpy(sched_string, kSchedFixedPriorityString, sizeof(sched_string));
-               kprintf("Scheduler: Default of %s\n", kSchedFixedPriorityString);
 #else
 #error No default scheduler implementation
 #endif
+               kprintf("Scheduler: Default of %s\n", SCHED(sched_name));
+       }
+
+       strlcpy(sched_string, SCHED(sched_name), sizeof(sched_string));
+
+       if (PE_parse_boot_argn("sched_debug", &sched_debug_flags, sizeof(sched_debug_flags))) {
+               kprintf("Scheduler: Debug flags 0x%08x\n", sched_debug_flags);
        }
        
        SCHED(init)();
-       SCHED(fairshare_init)();
        sched_realtime_init();
        ast_init();
-       
+       sched_timer_deadline_tracking_init();
+
        SCHED(pset_init)(&pset0);
        SCHED(processor_init)(master_processor);
 }
@@ -579,10 +400,10 @@ sched_timebase_init(void)
        sched_realtime_timebase_init();
 }
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
+#if defined(CONFIG_SCHED_TIMESHARE_CORE)
 
-static void
-sched_traditional_init(void)
+void
+sched_timeshare_init(void)
 {
        /*
         * Calculate the timeslicing quantum
@@ -594,13 +415,19 @@ sched_traditional_init(void)
 
        printf("standard timeslicing quantum is %d us\n", std_quantum_us);
 
+       if (default_bg_preemption_rate < 1)
+               default_bg_preemption_rate = DEFAULT_BG_PREEMPTION_RATE;
+       bg_quantum_us = (1000 * 1000) / default_bg_preemption_rate;
+
+       printf("standard background quantum is %d us\n", bg_quantum_us);
+
        load_shift_init();
        preempt_pri_init();
        sched_tick = 0;
 }
 
-static void
-sched_traditional_timebase_init(void)
+void
+sched_timeshare_timebase_init(void)
 {
        uint64_t        abstime;
        uint32_t        shift;
@@ -616,6 +443,12 @@ sched_traditional_timebase_init(void)
        assert((abstime >> 32) == 0 && (uint32_t)abstime != 0);
        min_std_quantum = (uint32_t)abstime;
 
+       /* quantum for background tasks */
+       clock_interval_to_absolutetime_interval(
+                                                       bg_quantum_us, NSEC_PER_USEC, &abstime);
+       assert((abstime >> 32) == 0 && (uint32_t)abstime != 0);
+       bg_quantum = (uint32_t)abstime;
+
        /* scheduler tick interval */
        clock_interval_to_absolutetime_interval(USEC_PER_SEC >> SCHED_TICK_SHIFT,
                                                                                                        NSEC_PER_USEC, &abstime);
@@ -631,58 +464,28 @@ sched_traditional_timebase_init(void)
                abstime >>= 1;
        sched_fixed_shift = shift;
 
-       max_unsafe_computation = max_unsafe_quanta * std_quantum;
-       sched_safe_duration = 2 * max_unsafe_quanta * std_quantum;
+       max_unsafe_computation = ((uint64_t)max_unsafe_quanta) * std_quantum;
+       sched_safe_duration = 2 * ((uint64_t)max_unsafe_quanta) * std_quantum;
        
-       max_poll_computation = max_poll_quanta * std_quantum;
+       max_poll_computation = ((uint64_t)max_poll_quanta) * std_quantum;
        thread_depress_time = 1 * std_quantum;
        default_timeshare_computation = std_quantum / 2;
        default_timeshare_constraint = std_quantum;
 
+#if defined(CONFIG_TELEMETRY)
+       /* interval for high frequency telemetry */
+       clock_interval_to_absolutetime_interval(10, NSEC_PER_MSEC, &abstime);
+       assert((abstime >> 32) == 0 && (uint32_t)abstime != 0);
+       sched_telemetry_interval = (uint32_t)abstime;
+#endif
 }
 
-static void
-sched_traditional_processor_init(processor_t processor)
-{
-       if (!sched_traditional_use_pset_runqueue) {
-               run_queue_init(&processor->runq);
-       }
-       processor->runq_bound_count = 0;
-}
-
-static void
-sched_traditional_pset_init(processor_set_t pset)
-{
-       if (sched_traditional_use_pset_runqueue) {
-               run_queue_init(&pset->pset_runq);
-       }
-       pset->pset_runq_bound_count = 0;
-}
-
-static void
-sched_traditional_with_pset_runqueue_init(void)
-{
-       sched_traditional_init();
-       sched_traditional_use_pset_runqueue = TRUE;
-}
-
-#endif /* CONFIG_SCHED_TRADITIONAL */
-
-#if defined(CONFIG_SCHED_TRADITIONAL) || defined(CONFIG_SCHED_PROTO) || defined(CONFIG_SCHED_GRRR) || defined(CONFIG_SCHED_FIXEDPRIORITY)
-void
-sched_traditional_fairshare_init(void)
-{
-       simple_lock_init(&fs_lock, 0);
-       
-       fs_runq.count = 0;
-       queue_init(&fs_runq.queue);
-}
-#endif
+#endif /* CONFIG_SCHED_TIMESHARE_CORE */
 
 static void
 sched_realtime_init(void)
 {
-       simple_lock_init(&rt_lock, 0);
+       rt_lock_init();
 
        rt_runq.count = 0;
        queue_init(&rt_runq.queue);
@@ -706,7 +509,7 @@ sched_realtime_timebase_init(void)
 
 }
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
+#if defined(CONFIG_SCHED_TIMESHARE_CORE)
 
 /*
  * Set up values for timeshare
@@ -718,10 +521,45 @@ load_shift_init(void)
        int8_t          k, *p = sched_load_shifts;
        uint32_t        i, j;
 
+       uint32_t        sched_decay_penalty = 1;
+
+       if (PE_parse_boot_argn("sched_decay_penalty", &sched_decay_penalty, sizeof (sched_decay_penalty))) {
+               kprintf("Overriding scheduler decay penalty %u\n", sched_decay_penalty);
+       }
+
+       if (PE_parse_boot_argn("sched_decay_usage_age_factor", &sched_decay_usage_age_factor, sizeof (sched_decay_usage_age_factor))) {
+               kprintf("Overriding scheduler decay usage age factor %u\n", sched_decay_usage_age_factor);
+       }
+
+       if (PE_parse_boot_argn("sched_use_combined_fgbg_decay", &sched_use_combined_fgbg_decay, sizeof (sched_use_combined_fgbg_decay))) {
+               kprintf("Overriding schedule fg/bg decay calculation: %u\n", sched_use_combined_fgbg_decay);
+       }
+
+       if (sched_decay_penalty == 0) {
+               /*
+                * There is no penalty for timeshare threads for using too much
+                * CPU, so set all load shifts to INT8_MIN. Even under high load,
+                * sched_pri_shift will be >INT8_MAX, and there will be no
+                * penalty applied to threads (nor will sched_usage be updated per
+                * thread).
+                */
+               for (i = 0; i < NRQS; i++) {
+                       sched_load_shifts[i] = INT8_MIN;
+               }
+
+               return;
+       }
+
        *p++ = INT8_MIN; *p++ = 0;
 
-       for (i = j = 2, k = 1; i < NRQS; ++k) {
-               for (j <<= 1; i < j; ++i)
+       /*
+        * For a given system load "i", the per-thread priority
+        * penalty per quantum of CPU usage is ~2^k priority
+        * levels. "sched_decay_penalty" can cause more
+        * array entries to be filled with smaller "k" values
+        */
+       for (i = 2, j = 1 << sched_decay_penalty, k = 1; i < NRQS; ++k) {
+               for (j <<= 1; (i < j) && (i < NRQS); ++i)
                        *p++ = k;
        }
 }
@@ -731,14 +569,14 @@ preempt_pri_init(void)
 {
        int             i, *p = sched_preempt_pri;
 
-       for (i = BASEPRI_FOREGROUND + 1; i < MINPRI_KERNEL; ++i)
+       for (i = BASEPRI_FOREGROUND; i < MINPRI_KERNEL; ++i)
                setbit(i, p);
 
        for (i = BASEPRI_PREEMPT; i <= MAXPRI; ++i)
                setbit(i, p);
 }
 
-#endif /* CONFIG_SCHED_TRADITIONAL */
+#endif /* CONFIG_SCHED_TIMESHARE_CORE */
 
 /*
  *     Thread wait timer expiration.
@@ -763,88 +601,25 @@ thread_timer_expire(
        splx(s);
 }
 
-#ifndef        __LP64__
-
-/*
- *     thread_set_timer:
- *
- *     Set a timer for the current thread, if the thread
- *     is ready to wait.  Must be called between assert_wait()
- *     and thread_block().
- */
-void
-thread_set_timer(
-       uint32_t                interval,
-       uint32_t                scale_factor)
-{
-       thread_t                thread = current_thread();
-       uint64_t                deadline;
-       spl_t                   s;
-
-       s = splsched();
-       thread_lock(thread);
-       if ((thread->state & TH_WAIT) != 0) {
-               clock_interval_to_deadline(interval, scale_factor, &deadline);
-               if (!timer_call_enter(&thread->wait_timer, deadline, thread->sched_pri >= BASEPRI_RTQUEUES ? TIMER_CALL_CRITICAL : 0))
-                       thread->wait_timer_active++;
-               thread->wait_timer_is_set = TRUE;
-       }
-       thread_unlock(thread);
-       splx(s);
-}
-
-void
-thread_set_timer_deadline(
-       uint64_t                deadline)
-{
-       thread_t                thread = current_thread();
-       spl_t                   s;
-
-       s = splsched();
-       thread_lock(thread);
-       if ((thread->state & TH_WAIT) != 0) {
-               if (!timer_call_enter(&thread->wait_timer, deadline, thread->sched_pri >= BASEPRI_RTQUEUES ? TIMER_CALL_CRITICAL : 0))
-                       thread->wait_timer_active++;
-               thread->wait_timer_is_set = TRUE;
-       }
-       thread_unlock(thread);
-       splx(s);
-}
-
-void
-thread_cancel_timer(void)
-{
-       thread_t                thread = current_thread();
-       spl_t                   s;
-
-       s = splsched();
-       thread_lock(thread);
-       if (thread->wait_timer_is_set) {
-               if (timer_call_cancel(&thread->wait_timer))
-                       thread->wait_timer_active--;
-               thread->wait_timer_is_set = FALSE;
-       }
-       thread_unlock(thread);
-       splx(s);
-}
-
-#endif /* __LP64__ */
-
 /*
  *     thread_unblock:
  *
  *     Unblock thread on wake up.
  *
- *     Returns TRUE if the thread is still running.
+ *     Returns TRUE if the thread should now be placed on the runqueue.
  *
  *     Thread must be locked.
+ *
+ *     Called at splsched().
  */
 boolean_t
 thread_unblock(
        thread_t                thread,
        wait_result_t   wresult)
 {
-       boolean_t               result = FALSE;
+       boolean_t               ready_for_runq = FALSE;
+       thread_t                cthread = current_thread();
+       uint32_t                new_run_count;
 
        /*
         *      Set wait_result.
@@ -868,17 +643,23 @@ thread_unblock(
 
        if (!(thread->state & TH_RUN)) {
                thread->state |= TH_RUN;
+               thread->last_made_runnable_time = mach_approximate_time();
+
+               ready_for_runq = TRUE;
 
                (*thread->sched_call)(SCHED_CALL_UNBLOCK, thread);
 
                /*
                 *      Update run counts.
                 */
-               sched_run_incr();
-               if (thread->sched_mode == TH_MODE_TIMESHARE)
-                       sched_share_incr();
-       }
-       else {
+               new_run_count = sched_run_incr(thread);
+               if (thread->sched_mode == TH_MODE_TIMESHARE) {
+                       sched_share_incr(thread);
+
+                       if (thread->sched_flags & TH_SFLAG_THROTTLED)
+                               sched_background_incr(thread);
+               }
+       } else {
                /*
                 *      Signal if idling on another processor.
                 */
@@ -893,31 +674,80 @@ thread_unblock(
                assert((thread->state & TH_IDLE) == 0);
 #endif
 
-               result = TRUE;
+               new_run_count = sched_run_count; /* updated in thread_select_idle() */
        }
 
+
        /*
         * Calculate deadline for real-time threads.
         */
        if (thread->sched_mode == TH_MODE_REALTIME) {
-               thread->realtime.deadline = mach_absolute_time();
-               thread->realtime.deadline += thread->realtime.constraint;
+               uint64_t ctime;
+
+               ctime = mach_absolute_time();
+               thread->realtime.deadline = thread->realtime.constraint + ctime;
        }
 
        /*
         * Clear old quantum, fail-safe computation, etc.
         */
-       thread->current_quantum = 0;
+       thread->quantum_remaining = 0;
        thread->computation_metered = 0;
        thread->reason = AST_NONE;
 
-       KERNEL_DEBUG_CONSTANT(
+       /* Obtain power-relevant interrupt and "platform-idle exit" statistics.
+        * We also account for "double hop" thread signaling via
+        * the thread callout infrastructure.
+        * DRK: consider removing the callout wakeup counters in the future
+        * they're present for verification at the moment.
+        */
+       boolean_t aticontext, pidle;
+       ml_get_power_state(&aticontext, &pidle);
+
+       if (__improbable(aticontext && !(thread_get_tag_internal(thread) & THREAD_TAG_CALLOUT))) {
+               ledger_credit(thread->t_ledger, task_ledgers.interrupt_wakeups, 1);
+               DTRACE_SCHED2(iwakeup, struct thread *, thread, struct proc *, thread->task->bsd_info);
+
+               uint64_t ttd = PROCESSOR_DATA(current_processor(), timer_call_ttd);
+
+               if (ttd) {
+                       if (ttd <= timer_deadline_tracking_bin_1)
+                               thread->thread_timer_wakeups_bin_1++;
+                       else
+                               if (ttd <= timer_deadline_tracking_bin_2)
+                                       thread->thread_timer_wakeups_bin_2++;
+               }
+
+               if (pidle) {
+                       ledger_credit(thread->t_ledger, task_ledgers.platform_idle_wakeups, 1);
+               }
+
+       } else if (thread_get_tag_internal(cthread) & THREAD_TAG_CALLOUT) {
+               if (cthread->callout_woken_from_icontext) {
+                       ledger_credit(thread->t_ledger, task_ledgers.interrupt_wakeups, 1);
+                       thread->thread_callout_interrupt_wakeups++;
+                       if (cthread->callout_woken_from_platform_idle) {
+                               ledger_credit(thread->t_ledger, task_ledgers.platform_idle_wakeups, 1);
+                               thread->thread_callout_platform_idle_wakeups++;
+                       }
+                       
+                       cthread->callout_woke_thread = TRUE;
+               }
+       }
+       
+       if (thread_get_tag_internal(thread) & THREAD_TAG_CALLOUT) {
+               thread->callout_woken_from_icontext = aticontext;
+               thread->callout_woken_from_platform_idle = pidle;
+               thread->callout_woke_thread = FALSE;
+       }
+
+       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
                MACHDBG_CODE(DBG_MACH_SCHED,MACH_MAKE_RUNNABLE) | DBG_FUNC_NONE,
-                                       (uintptr_t)thread_tid(thread), thread->sched_pri, 0, 0, 0);
+               (uintptr_t)thread_tid(thread), thread->sched_pri, thread->wait_result, new_run_count, 0);
 
        DTRACE_SCHED2(wakeup, struct thread *, thread, struct proc *, thread->task->bsd_info);
 
-       return (result);
+       return (ready_for_runq);
 }
 
 /*
@@ -927,27 +757,29 @@ thread_unblock(
  *     Conditions:
  *             thread lock held, IPC locks may be held.
  *             thread must have been pulled from wait queue under same lock hold.
- *  Returns:
+ *             thread must have been waiting
+ *     Returns:
  *             KERN_SUCCESS - Thread was set running
- *             KERN_NOT_WAITING - Thread was not waiting
+ *
+ * TODO: This should return void
  */
 kern_return_t
 thread_go(
-       thread_t                thread,
-       wait_result_t   wresult)
+          thread_t        thread,
+          wait_result_t   wresult)
 {
        assert(thread->at_safe_point == FALSE);
        assert(thread->wait_event == NO_EVENT64);
-       assert(thread->wait_queue == WAIT_QUEUE_NULL);
+       assert(thread->waitq == NULL);
 
-       if ((thread->state & (TH_WAIT|TH_TERMINATE)) == TH_WAIT) {
-               if (!thread_unblock(thread, wresult))
-                       thread_setrun(thread, SCHED_PREEMPT | SCHED_TAILQ);
+       assert(!(thread->state & (TH_TERMINATE|TH_TERMINATE2)));
+       assert(thread->state & TH_WAIT);
 
-               return (KERN_SUCCESS);
-       }
 
-       return (KERN_NOT_WAITING);
+       if (thread_unblock(thread, wresult))
+               thread_setrun(thread, SCHED_PREEMPT | SCHED_TAILQ);
+
+       return (KERN_SUCCESS);
 }
 
 /*
@@ -968,6 +800,7 @@ thread_mark_wait_locked(
        boolean_t               at_safe_point;
 
        assert(thread == current_thread());
+       assert(!(thread->state & (TH_WAIT|TH_IDLE|TH_UNINT|TH_TERMINATE2)));
 
        /*
         *      The thread may have certain types of interrupts/aborts masked
@@ -985,7 +818,8 @@ thread_mark_wait_locked(
                        (!at_safe_point &&
                                (thread->sched_flags & TH_SFLAG_ABORTSAFELY))) {
 
-               DTRACE_SCHED(sleep);
+               if ( !(thread->state & TH_TERMINATE))
+                       DTRACE_SCHED(sleep);
 
                thread->state |= (interruptible) ? TH_WAIT : (TH_WAIT | TH_UNINT);
                thread->at_safe_point = at_safe_point;
@@ -1043,7 +877,7 @@ assert_wait_possible(void)
        
        thread = current_thread();
 
-       return (thread == NULL || wait_queue_assert_possible(thread));
+       return (thread == NULL || waitq_wait_possible(thread));
 }
 
 /*
@@ -1057,14 +891,16 @@ assert_wait(
        event_t                         event,
        wait_interrupt_t        interruptible)
 {
-       register wait_queue_t   wq;
-       register int            index;
+       if (__improbable(event == NO_EVENT))
+               panic("%s() called with NO_EVENT", __func__);
 
-       assert(event != NO_EVENT);
+       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+               MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAIT)|DBG_FUNC_NONE,
+               VM_KERNEL_UNSLIDE(event), 0, 0, 0, 0);
 
-       index = wait_hash(event);
-       wq = &wait_queues[index];
-       return wait_queue_assert_wait(wq, event, interruptible, 0);
+       struct waitq *waitq;
+       waitq = global_eventq(event);
+       return waitq_assert_wait64(waitq, CAST_EVENT64_T(event), interruptible, TIMEOUT_WAIT_FOREVER);
 }
 
 wait_result_t
@@ -1076,140 +912,204 @@ assert_wait_timeout(
 {
        thread_t                        thread = current_thread();
        wait_result_t           wresult;
-       wait_queue_t            wqueue;
        uint64_t                        deadline;
        spl_t                           s;
 
-       assert(event != NO_EVENT);
-       wqueue = &wait_queues[wait_hash(event)];
+       if (__improbable(event == NO_EVENT))
+               panic("%s() called with NO_EVENT", __func__);
+
+       struct waitq *waitq;
+       waitq = global_eventq(event);
 
        s = splsched();
-       wait_queue_lock(wqueue);
+       waitq_lock(waitq);
        thread_lock(thread);
 
        clock_interval_to_deadline(interval, scale_factor, &deadline);
-       wresult = wait_queue_assert_wait64_locked(wqueue, CAST_DOWN(event64_t, event),
-                                                                                                       interruptible, deadline, thread);
+
+       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                                 MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAIT)|DBG_FUNC_NONE,
+                                 VM_KERNEL_UNSLIDE(event), interruptible, deadline, 0, 0);
+
+       wresult = waitq_assert_wait64_locked(waitq, CAST_EVENT64_T(event),
+                                            interruptible,
+                                            TIMEOUT_URGENCY_SYS_NORMAL,
+                                            deadline, TIMEOUT_NO_LEEWAY,
+                                            thread);
 
        thread_unlock(thread);
-       wait_queue_unlock(wqueue);
+       waitq_unlock(waitq);
        splx(s);
-
-       return (wresult);
+       return wresult;
 }
 
 wait_result_t
-assert_wait_deadline(
+assert_wait_timeout_with_leeway(
        event_t                         event,
        wait_interrupt_t        interruptible,
-       uint64_t                        deadline)
+       wait_timeout_urgency_t  urgency,
+       uint32_t                        interval,
+       uint32_t                        leeway,
+       uint32_t                        scale_factor)
 {
        thread_t                        thread = current_thread();
        wait_result_t           wresult;
-       wait_queue_t            wqueue;
+       uint64_t                        deadline;
+       uint64_t                        abstime;
+       uint64_t                        slop;
+       uint64_t                        now;
        spl_t                           s;
 
-       assert(event != NO_EVENT);
-       wqueue = &wait_queues[wait_hash(event)];
+       if (__improbable(event == NO_EVENT))
+               panic("%s() called with NO_EVENT", __func__);
+
+       now = mach_absolute_time();
+       clock_interval_to_absolutetime_interval(interval, scale_factor, &abstime);
+       deadline = now + abstime;
+
+       clock_interval_to_absolutetime_interval(leeway, scale_factor, &slop);
+
+       struct waitq *waitq;
+       waitq = global_eventq(event);
 
        s = splsched();
-       wait_queue_lock(wqueue);
+       waitq_lock(waitq);
        thread_lock(thread);
 
-       wresult = wait_queue_assert_wait64_locked(wqueue, CAST_DOWN(event64_t,event),
-                                                                                                       interruptible, deadline, thread);
+       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                                 MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAIT)|DBG_FUNC_NONE,
+                                 VM_KERNEL_UNSLIDE(event), interruptible, deadline, 0, 0);
+
+       wresult = waitq_assert_wait64_locked(waitq, CAST_EVENT64_T(event),
+                                            interruptible,
+                                            urgency, deadline, slop,
+                                            thread);
 
        thread_unlock(thread);
-       wait_queue_unlock(wqueue);
+       waitq_unlock(waitq);
        splx(s);
-
-       return (wresult);
+       return wresult;
 }
 
-/*
- *     thread_sleep_fast_usimple_lock:
- *
- *     Cause the current thread to wait until the specified event
- *     occurs.  The specified simple_lock is unlocked before releasing
- *     the cpu and re-acquired as part of waking up.
- *
- *     This is the simple lock sleep interface for components that use a
- *     faster version of simple_lock() than is provided by usimple_lock().
- */
-__private_extern__ wait_result_t
-thread_sleep_fast_usimple_lock(
-       event_t                 event,
-       simple_lock_t           lock,
-       wait_interrupt_t        interruptible)
-{
-       wait_result_t res;
+wait_result_t
+assert_wait_deadline(
+       event_t                         event,
+       wait_interrupt_t        interruptible,
+       uint64_t                        deadline)
+{
+       thread_t                        thread = current_thread();
+       wait_result_t           wresult;
+       spl_t                           s;
 
-       res = assert_wait(event, interruptible);
-       if (res == THREAD_WAITING) {
-               simple_unlock(lock);
-               res = thread_block(THREAD_CONTINUE_NULL);
-               simple_lock(lock);
-       }
-       return res;
-}
+       if (__improbable(event == NO_EVENT))
+               panic("%s() called with NO_EVENT", __func__);
 
+       struct waitq *waitq;
+       waitq = global_eventq(event);
+
+       s = splsched();
+       waitq_lock(waitq);
+       thread_lock(thread);
+
+       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                                 MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAIT)|DBG_FUNC_NONE,
+                                 VM_KERNEL_UNSLIDE(event), interruptible, deadline, 0, 0);
+
+       wresult = waitq_assert_wait64_locked(waitq, CAST_EVENT64_T(event),
+                                            interruptible,
+                                            TIMEOUT_URGENCY_SYS_NORMAL, deadline,
+                                            TIMEOUT_NO_LEEWAY, thread);
+       thread_unlock(thread);
+       waitq_unlock(waitq);
+       splx(s);
+       return wresult;
+}
 
-/*
- *     thread_sleep_usimple_lock:
- *
- *     Cause the current thread to wait until the specified event
- *     occurs.  The specified usimple_lock is unlocked before releasing
- *     the cpu and re-acquired as part of waking up.
- *
- *     This is the simple lock sleep interface for components where
- *     simple_lock() is defined in terms of usimple_lock().
- */
 wait_result_t
-thread_sleep_usimple_lock(
-       event_t                 event,
-       usimple_lock_t          lock,
-       wait_interrupt_t        interruptible)
+assert_wait_deadline_with_leeway(
+       event_t                         event,
+       wait_interrupt_t        interruptible,
+       wait_timeout_urgency_t  urgency,
+       uint64_t                        deadline,
+       uint64_t                        leeway)
 {
-       wait_result_t res;
+       thread_t                        thread = current_thread();
+       wait_result_t           wresult;
+       spl_t                           s;
 
-       res = assert_wait(event, interruptible);
-       if (res == THREAD_WAITING) {
-               usimple_unlock(lock);
-               res = thread_block(THREAD_CONTINUE_NULL);
-               usimple_lock(lock);
-       }
-       return res;
+       if (__improbable(event == NO_EVENT))
+               panic("%s() called with NO_EVENT", __func__);
+
+       struct waitq *waitq;
+       waitq = global_eventq(event);
+
+       s = splsched();
+       waitq_lock(waitq);
+       thread_lock(thread);
+
+       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                                 MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAIT)|DBG_FUNC_NONE,
+                                 VM_KERNEL_UNSLIDE(event), interruptible, deadline, 0, 0);
+
+       wresult = waitq_assert_wait64_locked(waitq, CAST_EVENT64_T(event),
+                                            interruptible,
+                                            urgency, deadline, leeway,
+                                            thread);
+
+       thread_unlock(thread);
+       waitq_unlock(waitq);
+       splx(s);
+       return wresult;
 }
 
 /*
- *     thread_sleep_lock_write:
+ * thread_isoncpu:
  *
- *     Cause the current thread to wait until the specified event
- *     occurs.  The specified (write) lock is unlocked before releasing
- *     the cpu. The (write) lock will be re-acquired before returning.
+ * Return TRUE if a thread is running on a processor such that an AST
+ * is needed to pull it out of userspace execution, or if executing in
+ * the kernel, bring to a context switch boundary that would cause
+ * thread state to be serialized in the thread PCB.
+ * 
+ * Thread locked, returns the same way. While locked, fields
+ * like "state" cannot change. "runq" can change only from set to unset.
  */
-wait_result_t
-thread_sleep_lock_write(
-       event_t                 event,
-       lock_t                  *lock,
-       wait_interrupt_t interruptible)
+static inline boolean_t
+thread_isoncpu(thread_t thread)
 {
-       wait_result_t   res;
+       /* Not running or runnable */
+       if (!(thread->state & TH_RUN))
+               return (FALSE);
 
-       res = assert_wait(event, interruptible);
-       if (res == THREAD_WAITING) {
-               lock_write_done(lock);
-               res = thread_block(THREAD_CONTINUE_NULL);
-               lock_write(lock);
-       }
-       return res;
+       /* Waiting on a runqueue, not currently running */
+       /* TODO: This is invalid - it can get dequeued without thread lock, but not context switched. */
+       if (thread->runq != PROCESSOR_NULL)
+               return (FALSE);
+
+       /*
+        * Thread does not have a stack yet
+        * It could be on the stack alloc queue or preparing to be invoked
+        */
+       if (!thread->kernel_stack)
+               return (FALSE);
+
+       /*
+        * Thread must be running on a processor, or
+        * about to run, or just did run. In all these
+        * cases, an AST to the processor is needed
+        * to guarantee that the thread is kicked out
+        * of userspace and the processor has
+        * context switched (and saved register state).
+        */
+       return (TRUE);
 }
 
 /*
  * thread_stop:
  *
  * Force a preemption point for a thread and wait
- * for it to stop running.  Arbitrates access among
+ * for it to stop running on a CPU. If a stronger
+ * guarantee is requested, wait until no longer
+ * runnable. Arbitrates access among
  * multiple stop requests. (released by unstop)
  *
  * The thread must enter a wait state and stop via a
@@ -1219,10 +1119,12 @@ thread_sleep_lock_write(
  */
 boolean_t
 thread_stop(
-       thread_t                thread)
+       thread_t                thread,
+       boolean_t       until_not_runnable)
 {
        wait_result_t   wresult;
        spl_t                   s = splsched();
+       boolean_t               oncpu;
 
        wake_lock(thread);
        thread_lock(thread);
@@ -1248,11 +1150,15 @@ thread_stop(
 
        thread->state |= TH_SUSP;
 
-       while (thread->state & TH_RUN) {
-               processor_t             processor = thread->last_processor;
-
-               if (processor != PROCESSOR_NULL && processor->active_thread == thread)
+       while ((oncpu = thread_isoncpu(thread)) ||
+                  (until_not_runnable && (thread->state & TH_RUN))) {
+               processor_t             processor;
+               
+               if (oncpu) {
+                       assert(thread->state & TH_RUN);
+                       processor = thread->chosen_processor;
                        cause_ast_check(processor);
+               }
 
                thread->wake_active = TRUE;
                thread_unlock(thread);
@@ -1277,6 +1183,13 @@ thread_stop(
        thread_unlock(thread);
        wake_unlock(thread);
        splx(s);
+       
+       /*
+        * We return with the thread unlocked. To prevent it from
+        * transitioning to a runnable state (or from TH_RUN to
+        * being on the CPU), the caller must ensure the thread
+        * is stopped via an external means (such as an AST)
+        */
 
        return (TRUE);
 }
@@ -1298,13 +1211,8 @@ thread_unstop(
        wake_lock(thread);
        thread_lock(thread);
 
-       if ((thread->state & (TH_RUN|TH_WAIT|TH_SUSP)) == TH_SUSP) {
-               thread->state &= ~TH_SUSP;
-               thread_unblock(thread, THREAD_AWAKENED);
+       assert((thread->state & (TH_RUN|TH_WAIT|TH_SUSP)) != TH_SUSP);
 
-               thread_setrun(thread, SCHED_PREEMPT | SCHED_TAILQ);
-       }
-       else
        if (thread->state & TH_SUSP) {
                thread->state &= ~TH_SUSP;
 
@@ -1333,19 +1241,32 @@ thread_unstop(
  */
 void
 thread_wait(
-       thread_t                thread)
+       thread_t        thread,
+       boolean_t       until_not_runnable)
 {
        wait_result_t   wresult;
-       spl_t                   s = splsched();
+       boolean_t       oncpu;
+       processor_t     processor;
+       spl_t           s = splsched();
 
        wake_lock(thread);
        thread_lock(thread);
 
-       while (thread->state & TH_RUN) {
-               processor_t             processor = thread->last_processor;
+       /*
+        * Wait until not running on a CPU.  If stronger requirement
+        * desired, wait until not runnable.  Assumption: if thread is
+        * on CPU, then TH_RUN is set, so we're not waiting in any case
+        * where the original, pure "TH_RUN" check would have let us 
+        * finish.
+        */
+       while ((oncpu = thread_isoncpu(thread)) ||
+                       (until_not_runnable && (thread->state & TH_RUN))) {
 
-               if (processor != PROCESSOR_NULL && processor->active_thread == thread)
+               if (oncpu) {
+                       assert(thread->state & TH_RUN);
+                       processor = thread->chosen_processor;
                        cause_ast_check(processor);
+               }
 
                thread->wake_active = TRUE;
                thread_unlock(thread);
@@ -1388,35 +1309,37 @@ clear_wait_internal(
        thread_t                thread,
        wait_result_t   wresult)
 {
-       wait_queue_t    wq = thread->wait_queue;
        uint32_t        i = LockTimeOut;
+       struct waitq *waitq = thread->waitq;
 
        do {
                if (wresult == THREAD_INTERRUPTED && (thread->state & TH_UNINT))
                        return (KERN_FAILURE);
 
-               if (wq != WAIT_QUEUE_NULL) {
-                       if (wait_queue_lock_try(wq)) {
-                               wait_queue_pull_thread_locked(wq, thread, TRUE);
-                               /* wait queue unlocked, thread still locked */
-                       }
-                       else {
+               if (waitq != NULL) {
+                       assert(waitq_irq_safe(waitq)); //irqs are already disabled!
+                       if (waitq_lock_try(waitq)) {
+                               waitq_pull_thread_locked(waitq, thread);
+                               waitq_unlock(waitq);
+                       else {
                                thread_unlock(thread);
                                delay(1);
-
                                thread_lock(thread);
-                               if (wq != thread->wait_queue)
-                                       return (KERN_NOT_WAITING);
-
+                               if (waitq != thread->waitq)
+                                       return KERN_NOT_WAITING;
                                continue;
                        }
                }
 
-               return (thread_go(thread, wresult));
+               /* TODO: Can we instead assert TH_TERMINATE is not set?  */
+               if ((thread->state & (TH_WAIT|TH_TERMINATE)) == TH_WAIT)
+                       return (thread_go(thread, wresult));
+               else
+                       return (KERN_NOT_WAITING);
        } while ((--i > 0) || machine_timeout_suspended());
 
        panic("clear_wait_internal: deadlock: thread=%p, wq=%p, cpu=%d\n",
-                 thread, wq, cpu_number());
+                 thread, waitq, cpu_number());
 
        return (KERN_FAILURE);
 }
@@ -1473,21 +1396,25 @@ thread_wakeup_prim_internal(
        wait_result_t           result,
        int                     priority)
 {
-       register wait_queue_t   wq;
-       register int                    index;
+       if (__improbable(event == NO_EVENT))
+               panic("%s() called with NO_EVENT", __func__);
+
+       struct waitq *wq;
+
+       wq = global_eventq(event);
+       priority = (priority == -1 ? WAITQ_ALL_PRIORITIES : priority);
 
-       index = wait_hash(event);
-       wq = &wait_queues[index];
        if (one_thread)
-               return (wait_queue_wakeup_one(wq, event, result, priority));
+               return waitq_wakeup64_one(wq, CAST_EVENT64_T(event), result, priority);
        else
-               return (wait_queue_wakeup_all(wq, event, result));
+               return waitq_wakeup64_all(wq, CAST_EVENT64_T(event), result, priority);
 }
 
 /*
  *     thread_bind:
  *
  *     Force the current thread to execute on the specified processor.
+ *     Takes effect after the next thread_block().
  *
  *     Returns the previous binding.  PROCESSOR_NULL means
  *     not bound.
@@ -1505,8 +1432,7 @@ thread_bind(
        s = splsched();
        thread_lock(self);
 
-       prev = self->bound_processor;
-       self->bound_processor = processor;
+       prev = thread_bind_internal(self, processor);
 
        thread_unlock(self);
        splx(s);
@@ -1514,6 +1440,254 @@ thread_bind(
        return (prev);
 }
 
+/*
+ * thread_bind_internal:
+ *
+ * If the specified thread is not the current thread, and it is currently
+ * running on another CPU, a remote AST must be sent to that CPU to cause
+ * the thread to migrate to its bound processor. Otherwise, the migration
+ * will occur at the next quantum expiration or blocking point.
+ *
+ * When the thread is the current thread, and explicit thread_block() should
+ * be used to force the current processor to context switch away and
+ * let the thread migrate to the bound processor.
+ *
+ * Thread must be locked, and at splsched.
+ */
+
+static processor_t
+thread_bind_internal(
+       thread_t                thread,
+       processor_t             processor)
+{
+       processor_t             prev;
+
+       /* <rdar://problem/15102234> */
+       assert(thread->sched_pri < BASEPRI_RTQUEUES);
+       /* A thread can't be bound if it's sitting on a (potentially incorrect) runqueue */
+       assert(thread->runq == PROCESSOR_NULL);
+
+       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_THREAD_BIND), thread_tid(thread), processor ? (uintptr_t)processor->cpu_id : (uintptr_t)-1, 0, 0, 0);
+
+       prev = thread->bound_processor;
+       thread->bound_processor = processor;
+
+       return (prev);
+}
+
+/*
+ * thread_vm_bind_group_add:
+ *
+ * The "VM bind group" is a special mechanism to mark a collection
+ * of threads from the VM subsystem that, in general, should be scheduled
+ * with only one CPU of parallelism. To accomplish this, we initially
+ * bind all the threads to the master processor, which has the effect
+ * that only one of the threads in the group can execute at once, including
+ * preempting threads in the group that are a lower priority. Future
+ * mechanisms may use more dynamic mechanisms to prevent the collection
+ * of VM threads from using more CPU time than desired.
+ *
+ * The current implementation can result in priority inversions where
+ * compute-bound priority 95 or realtime threads that happen to have
+ * landed on the master processor prevent the VM threads from running.
+ * When this situation is detected, we unbind the threads for one
+ * scheduler tick to allow the scheduler to run the threads an
+ * additional CPUs, before restoring the binding (assuming high latency
+ * is no longer a problem).
+ */
+
+/*
+ * The current max is provisioned for:
+ * vm_compressor_swap_trigger_thread (92)
+ * 2 x vm_pageout_iothread_internal (92) when vm_restricted_to_single_processor==TRUE
+ * vm_pageout_continue (92)
+ * memorystatus_thread (95)
+ */
+#define MAX_VM_BIND_GROUP_COUNT (5)
+decl_simple_lock_data(static,sched_vm_group_list_lock);
+static thread_t sched_vm_group_thread_list[MAX_VM_BIND_GROUP_COUNT];
+static int sched_vm_group_thread_count;
+static boolean_t sched_vm_group_temporarily_unbound = FALSE;
+
+void
+thread_vm_bind_group_add(void)
+{
+       thread_t self = current_thread();
+
+       thread_reference_internal(self);
+       self->options |= TH_OPT_SCHED_VM_GROUP;
+
+       simple_lock(&sched_vm_group_list_lock);
+       assert(sched_vm_group_thread_count < MAX_VM_BIND_GROUP_COUNT);
+       sched_vm_group_thread_list[sched_vm_group_thread_count++] = self;
+       simple_unlock(&sched_vm_group_list_lock);
+
+       thread_bind(master_processor);
+
+       /* Switch to bound processor if not already there */
+       thread_block(THREAD_CONTINUE_NULL);
+}
+
+static void
+sched_vm_group_maintenance(void)
+{
+       uint64_t ctime = mach_absolute_time();
+       uint64_t longtime = ctime - sched_tick_interval;
+       int i;
+       spl_t s;
+       boolean_t high_latency_observed = FALSE;
+       boolean_t runnable_and_not_on_runq_observed = FALSE;
+       boolean_t bind_target_changed = FALSE;
+       processor_t bind_target = PROCESSOR_NULL;
+
+       /* Make sure nobody attempts to add new threads while we are enumerating them */
+       simple_lock(&sched_vm_group_list_lock);
+
+       s = splsched();
+
+       for (i=0; i < sched_vm_group_thread_count; i++) {
+               thread_t thread = sched_vm_group_thread_list[i];
+               assert(thread != THREAD_NULL);
+               thread_lock(thread);
+               if ((thread->state & (TH_RUN|TH_WAIT)) == TH_RUN) {
+                       if (thread->runq != PROCESSOR_NULL && thread->last_made_runnable_time < longtime) {
+                               high_latency_observed = TRUE;
+                       } else if (thread->runq == PROCESSOR_NULL) {
+                               /* There are some cases where a thread be transitiong that also fall into this case */
+                               runnable_and_not_on_runq_observed = TRUE;
+                       }
+               }
+               thread_unlock(thread);
+
+               if (high_latency_observed && runnable_and_not_on_runq_observed) {
+                       /* All the things we are looking for are true, stop looking */
+                       break;
+               }
+       }
+
+       splx(s);
+
+       if (sched_vm_group_temporarily_unbound) {
+               /* If we turned off binding, make sure everything is OK before rebinding */
+               if (!high_latency_observed) {
+                       /* rebind */
+                       bind_target_changed = TRUE;
+                       bind_target = master_processor;
+                       sched_vm_group_temporarily_unbound = FALSE; /* might be reset to TRUE if change cannot be completed */
+               }
+       } else {
+               /*
+                * Check if we're in a bad state, which is defined by high
+                * latency with no core currently executing a thread. If a
+                * single thread is making progress on a CPU, that means the
+                * binding concept to reduce parallelism is working as
+                * designed.
+                */
+               if (high_latency_observed && !runnable_and_not_on_runq_observed) {
+                       /* unbind */
+                       bind_target_changed = TRUE;
+                       bind_target = PROCESSOR_NULL;
+                       sched_vm_group_temporarily_unbound = TRUE;
+               }
+       }
+
+       if (bind_target_changed) {
+               s = splsched();
+               for (i=0; i < sched_vm_group_thread_count; i++) {
+                       thread_t thread = sched_vm_group_thread_list[i];
+                       boolean_t removed;
+                       assert(thread != THREAD_NULL);
+
+                       thread_lock(thread);
+                       removed = thread_run_queue_remove(thread);
+                       if (removed || ((thread->state & (TH_RUN | TH_WAIT)) == TH_WAIT)) {
+                               thread_bind_internal(thread, bind_target);
+                       } else {
+                               /*
+                                * Thread was in the middle of being context-switched-to,
+                                * or was in the process of blocking. To avoid switching the bind
+                                * state out mid-flight, defer the change if possible.
+                                */
+                               if (bind_target == PROCESSOR_NULL) {
+                                       thread_bind_internal(thread, bind_target);
+                               } else {
+                                       sched_vm_group_temporarily_unbound = TRUE; /* next pass will try again */
+                               }
+                       }
+
+                       if (removed) {
+                               thread_run_queue_reinsert(thread, SCHED_PREEMPT | SCHED_TAILQ);
+                       }
+                       thread_unlock(thread);
+               }
+               splx(s);
+       }
+
+       simple_unlock(&sched_vm_group_list_lock);
+}
+
+/* Invoked prior to idle entry to determine if, on SMT capable processors, an SMT
+ * rebalancing opportunity exists when a core is (instantaneously) idle, but
+ * other SMT-capable cores may be over-committed. TODO: some possible negatives:
+ * IPI thrash if this core does not remain idle following the load balancing ASTs
+ * Idle "thrash", when IPI issue is followed by idle entry/core power down
+ * followed by a wakeup shortly thereafter.
+ */
+
+#if (DEVELOPMENT || DEBUG)
+int sched_smt_balance = 1;
+#endif
+
+#if __SMP__
+/* Invoked with pset locked, returns with pset unlocked */
+static void
+sched_SMT_balance(processor_t cprocessor, processor_set_t cpset) {
+       processor_t ast_processor = NULL;
+
+#if (DEVELOPMENT || DEBUG)
+       if (__improbable(sched_smt_balance == 0))
+               goto smt_balance_exit;
+#endif
+       
+       assert(cprocessor == current_processor());
+       if (cprocessor->is_SMT == FALSE)
+               goto smt_balance_exit;
+
+       processor_t sib_processor = cprocessor->processor_secondary ? cprocessor->processor_secondary : cprocessor->processor_primary;
+
+       /* Determine if both this processor and its sibling are idle,
+        * indicating an SMT rebalancing opportunity.
+        */
+       if (sib_processor->state != PROCESSOR_IDLE)
+               goto smt_balance_exit;
+
+       processor_t sprocessor;
+
+       sprocessor = (processor_t)queue_first(&cpset->active_queue);
+
+       while (!queue_end(&cpset->active_queue, (queue_entry_t)sprocessor)) {
+               if ((sprocessor->state == PROCESSOR_RUNNING) &&
+                   (sprocessor->processor_primary != sprocessor) &&
+                   (sprocessor->processor_primary->state == PROCESSOR_RUNNING) &&
+                   (sprocessor->current_pri < BASEPRI_RTQUEUES) &&
+                   ((cpset->pending_AST_cpu_mask & (1ULL << sprocessor->cpu_id)) == 0)) {
+                       assert(sprocessor != cprocessor);
+                       ast_processor = sprocessor;
+                       break;
+               }
+               sprocessor = (processor_t)queue_next((queue_entry_t)sprocessor);
+       }
+
+smt_balance_exit:
+       pset_unlock(cpset);
+
+       if (ast_processor) {
+               KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_SMT_BALANCE), ast_processor->cpu_id, ast_processor->state, ast_processor->processor_primary->state, 0, 0);
+               cause_ast_check(ast_processor);
+       }
+}
+#endif /* __SMP__ */
+
 /*
  *     thread_select:
  *
@@ -1524,13 +1698,14 @@ thread_bind(
 static thread_t
 thread_select(
        thread_t                        thread,
-       processor_t                     processor)
+       processor_t                     processor,
+       ast_t                           reason)
 {
        processor_set_t         pset = processor->processor_set;
        thread_t                        new_thread = THREAD_NULL;
-       boolean_t                       inactive_state;
 
        assert(processor == current_processor());
+       assert((thread->state & (TH_RUN|TH_TERMINATE2)) == TH_RUN);
 
        do {
                /*
@@ -1541,156 +1716,148 @@ thread_select(
                
                processor->current_pri = thread->sched_pri;
                processor->current_thmode = thread->sched_mode;
+               processor->current_sfi_class = thread->sfi_class;
 
                pset_lock(pset);
 
-               assert(pset->low_count);
-               assert(pset->low_pri);
+               assert(processor->state != PROCESSOR_OFF_LINE);
 
-               inactive_state = processor->state != PROCESSOR_SHUTDOWN && machine_processor_is_inactive(processor);
+               if (!processor->is_recommended) {
+                       /*
+                        * The performance controller has provided a hint to not dispatch more threads,
+                        * unless they are bound to us (and thus we are the only option
+                        */
+                       if (!SCHED(processor_bound_count)(processor)) {
+                               goto idle;
+                       }
+               } else if (processor->processor_primary != processor) {
+                       /*
+                        * Should this secondary SMT processor attempt to find work? For pset runqueue systems,
+                        * we should look for work only under the same conditions that choose_processor()
+                        * would have assigned work, which is when all primary processors have been assigned work.
+                        *
+                        * An exception is that bound threads are dispatched to a processor without going through
+                        * choose_processor(), so in those cases we should continue trying to dequeue work.
+                        */
+                       if (!SCHED(processor_bound_count)(processor) && !queue_empty(&pset->idle_queue) && !rt_runq.count) {
+                               goto idle;
+                       }
+               }
 
-               simple_lock(&rt_lock);
+               rt_lock_lock();
 
                /*
                 *      Test to see if the current thread should continue
-                *      to run on this processor.  Must be runnable, and not
+                *      to run on this processor.  Must not be attempting to wait, and not
                 *      bound to a different processor, nor be in the wrong
-                *      processor set.
+                *      processor set, nor be forced to context switch by TH_SUSP.
+                *
+                *      Note that there are never any RT threads in the regular runqueue.
+                *
+                *      This code is very insanely tricky.
                 */
-               if (    ((thread->state & ~TH_SUSP) == TH_RUN)                                  &&
-                               (thread->sched_pri >= BASEPRI_RTQUEUES          ||
-                                processor->processor_meta == PROCESSOR_META_NULL ||
-                                processor->processor_meta->primary == processor)               &&
-                               (thread->bound_processor == PROCESSOR_NULL      ||
-                                thread->bound_processor == processor)                  &&
-                               (thread->affinity_set == AFFINITY_SET_NULL      ||
-                                thread->affinity_set->aset_pset == pset)                       ) {
-                       if (    thread->sched_pri >= BASEPRI_RTQUEUES   &&
-                                               first_timeslice(processor)                              ) {
+
+               if (((thread->state & (TH_TERMINATE|TH_IDLE|TH_WAIT|TH_RUN|TH_SUSP)) == TH_RUN) &&
+                   (thread->sched_pri >= BASEPRI_RTQUEUES     || processor->processor_primary == processor) &&
+                   (thread->bound_processor == PROCESSOR_NULL || thread->bound_processor == processor)      &&
+                   (thread->affinity_set == AFFINITY_SET_NULL || thread->affinity_set->aset_pset == pset)) {
+                       /*
+                        * RT threads with un-expired quantum stay on processor,
+                        * unless there's a valid RT thread with an earlier deadline.
+                        */
+                       if (thread->sched_pri >= BASEPRI_RTQUEUES && processor->first_timeslice) {
                                if (rt_runq.count > 0) {
-                                       register queue_t                q;
-
-                                       q = &rt_runq.queue;
-                                       if (((thread_t)q->next)->realtime.deadline <
-                                                                                                       processor->deadline) {
-                                               thread = (thread_t)dequeue_head(q);
-                                               thread->runq = PROCESSOR_NULL;
-                                               SCHED_STATS_RUNQ_CHANGE(&rt_runq.runq_stats, rt_runq.count);
-                                               rt_runq.count--;
+                                       thread_t next_rt;
+
+                                       next_rt = (thread_t)queue_first(&rt_runq.queue);
+
+                                       assert(next_rt->runq == THREAD_ON_RT_RUNQ);
+
+                                       if (next_rt->realtime.deadline < processor->deadline &&
+                                           (next_rt->bound_processor == PROCESSOR_NULL ||
+                                            next_rt->bound_processor == processor)) {
+                                               /* The next RT thread is better, so pick it off the runqueue. */
+                                               goto pick_new_rt_thread;
                                        }
                                }
 
-                               simple_unlock(&rt_lock);
-
+                               /* This is still the best RT thread to run. */
                                processor->deadline = thread->realtime.deadline;
 
+                               rt_lock_unlock();
                                pset_unlock(pset);
 
                                return (thread);
                        }
 
-                       if (!inactive_state && (thread->sched_mode != TH_MODE_FAIRSHARE || SCHED(fairshare_runq_count)() == 0) && (rt_runq.count == 0 || BASEPRI_RTQUEUES < thread->sched_pri) &&
-                                       (new_thread = SCHED(choose_thread)(processor, thread->sched_mode == TH_MODE_FAIRSHARE ? MINPRI : thread->sched_pri)) == THREAD_NULL) {
-
-                               simple_unlock(&rt_lock);
-
-                               /* I am the highest priority runnable (non-idle) thread */
-
-                               pset_pri_hint(pset, processor, processor->current_pri);
-
-                               pset_count_hint(pset, processor, SCHED(processor_runq_count)(processor));
-
+                       if ((rt_runq.count == 0) &&
+                           SCHED(processor_queue_has_priority)(processor, thread->sched_pri, TRUE) == FALSE) {
+                               /* This thread is still the highest priority runnable (non-idle) thread */
                                processor->deadline = UINT64_MAX;
 
+                               rt_lock_unlock();
                                pset_unlock(pset);
 
                                return (thread);
                        }
                }
 
-               if (new_thread != THREAD_NULL ||
-                               (SCHED(processor_queue_has_priority)(processor, rt_runq.count == 0 ? IDLEPRI : BASEPRI_RTQUEUES, TRUE) &&
-                                        (new_thread = SCHED(choose_thread)(processor, MINPRI)) != THREAD_NULL)) {
-                               simple_unlock(&rt_lock);
-
-                               if (!inactive_state) {
-                                       pset_pri_hint(pset, processor, new_thread->sched_pri);
-
-                                       pset_count_hint(pset, processor, SCHED(processor_runq_count)(processor));
-                               }
-
-                               processor->deadline = UINT64_MAX;
-                               pset_unlock(pset);
+               /* OK, so we're not going to run the current thread. Look at the RT queue. */
+               if (rt_runq.count > 0) {
+                       thread_t next_rt = (thread_t)queue_first(&rt_runq.queue);
 
-                               return (new_thread);
-               }
+                       assert(next_rt->runq == THREAD_ON_RT_RUNQ);
 
-               if (rt_runq.count > 0) {
-                       thread = (thread_t)dequeue_head(&rt_runq.queue);
+                       if (__probable((next_rt->bound_processor == PROCESSOR_NULL ||
+                                      (next_rt->bound_processor == processor)))) {
+pick_new_rt_thread:
+                               new_thread = (thread_t)dequeue_head(&rt_runq.queue);
 
-                       thread->runq = PROCESSOR_NULL;
-                       SCHED_STATS_RUNQ_CHANGE(&rt_runq.runq_stats, rt_runq.count);
-                       rt_runq.count--;
+                               new_thread->runq = PROCESSOR_NULL;
+                               SCHED_STATS_RUNQ_CHANGE(&rt_runq.runq_stats, rt_runq.count);
+                               rt_runq.count--;
 
-                       simple_unlock(&rt_lock);
+                               processor->deadline = new_thread->realtime.deadline;
 
-                       processor->deadline = thread->realtime.deadline;
-                       pset_unlock(pset);
+                               rt_lock_unlock();
+                               pset_unlock(pset);
 
-                       return (thread);
+                               return (new_thread);
+                       }
                }
 
-               simple_unlock(&rt_lock);
-
-               /* No realtime threads and no normal threads on the per-processor
-                * runqueue. Finally check for global fairshare threads.
-                */
-               if ((new_thread = SCHED(fairshare_dequeue)()) != THREAD_NULL) {
+               processor->deadline = UINT64_MAX;
+               rt_lock_unlock();
 
-                       processor->deadline = UINT64_MAX;
+               /* No RT threads, so let's look at the regular threads. */
+               if ((new_thread = SCHED(choose_thread)(processor, MINPRI, reason)) != THREAD_NULL) {
                        pset_unlock(pset);
-                       
                        return (new_thread);
                }
-                       
-               processor->deadline = UINT64_MAX;
-
-               /*
-                *      Set processor inactive based on
-                *      indication from the platform code.
-                */
-               if (inactive_state) {
-                       if (processor->state == PROCESSOR_RUNNING)
-                               remqueue((queue_entry_t)processor);
-                       else
-                       if (processor->state == PROCESSOR_IDLE)
-                               remqueue((queue_entry_t)processor);
 
-                       processor->state = PROCESSOR_INACTIVE;
+#if __SMP__
+               if (SCHED(steal_thread_enabled)) {
+                       /*
+                        * No runnable threads, attempt to steal
+                        * from other processors. Returns with pset lock dropped.
+                        */
 
-                       pset_unlock(pset);
+                       if ((new_thread = SCHED(steal_thread)(pset)) != THREAD_NULL) {
+                               return (new_thread);
+                       }
 
-                       return (processor->idle_thread);
-               }
+                       /*
+                        * If other threads have appeared, shortcut
+                        * around again.
+                        */
+                       if (!SCHED(processor_queue_empty)(processor) || rt_runq.count > 0)
+                               continue;
 
-               /*
-                *      No runnable threads, attempt to steal
-                *      from other processors.
-                */
-               new_thread = SCHED(steal_thread)(pset);
-               if (new_thread != THREAD_NULL) {
-                       return (new_thread);
+                       pset_lock(pset);
                }
+#endif
 
-               /*
-                *      If other threads have appeared, shortcut
-                *      around again.
-                */
-               if (!SCHED(processor_queue_empty)(processor) || rt_runq.count > 0 || SCHED(fairshare_runq_count)() > 0)
-                       continue;
-
-               pset_lock(pset);
-
+       idle:
                /*
                 *      Nothing is runnable, so set this processor idle if it
                 *      was running.
@@ -1699,24 +1866,28 @@ thread_select(
                        remqueue((queue_entry_t)processor);
                        processor->state = PROCESSOR_IDLE;
 
-                       if (processor->processor_meta == PROCESSOR_META_NULL || processor->processor_meta->primary == processor) {
+                       if (processor->processor_primary == processor) {
                                enqueue_head(&pset->idle_queue, (queue_entry_t)processor);
-                               pset_pri_init_hint(pset, processor);
-                               pset_count_init_hint(pset, processor);
                        }
                        else {
-                               enqueue_head(&processor->processor_meta->idle_queue, (queue_entry_t)processor);
-                                       pset_unlock(pset);
-                                       return (processor->idle_thread);
+                               enqueue_head(&pset->idle_secondary_queue, (queue_entry_t)processor);
                        }
                }
 
+#if __SMP__
+               /* Invoked with pset locked, returns with pset unlocked */
+               sched_SMT_balance(processor, pset);
+#else
                pset_unlock(pset);
+#endif
 
 #if CONFIG_SCHED_IDLE_IN_PLACE
                /*
                 *      Choose idle thread if fast idle is not possible.
                 */
+               if (processor->processor_primary != processor)
+                       return (processor->idle_thread);
+
                if ((thread->state & (TH_IDLE|TH_TERMINATE|TH_SUSP)) || !(thread->state & TH_WAIT) || thread->wake_active || thread->sched_pri >= BASEPRI_RTQUEUES)
                        return (processor->idle_thread);
 
@@ -1734,7 +1905,7 @@ thread_select(
                 * thread can start running on another processor without
                 * waiting for the fast-idled processor to wake up.
                 */
-               return (processor->idle_thread);
+               new_thread = processor->idle_thread;
 
 #endif /* !CONFIG_SCHED_IDLE_IN_PLACE */
 
@@ -1757,34 +1928,49 @@ thread_select_idle(
        processor_t             processor)
 {
        thread_t                new_thread;
+       uint64_t                arg1, arg2;
+       int                     urgency;
+
+       if (thread->sched_mode == TH_MODE_TIMESHARE) {
+               if (thread->sched_flags & TH_SFLAG_THROTTLED)
+                       sched_background_decr(thread);
 
-       if (thread->sched_mode == TH_MODE_TIMESHARE)
-               sched_share_decr();
-       sched_run_decr();
+               sched_share_decr(thread);
+       }
+       sched_run_decr(thread);
 
        thread->state |= TH_IDLE;
        processor->current_pri = IDLEPRI;
        processor->current_thmode = TH_MODE_NONE;
+       processor->current_sfi_class = SFI_CLASS_KERNEL;
 
+       /* Reload precise timing global policy to thread-local policy */
+       thread->precise_user_kernel_time = use_precise_user_kernel_time(thread);
+       
        thread_unlock(thread);
 
        /*
         *      Switch execution timing to processor idle thread.
         */
        processor->last_dispatch = mach_absolute_time();
-       thread->last_run_time = processor->last_dispatch;
-       thread_timer_event(processor->last_dispatch, &processor->idle_thread->system_timer);
+
+#ifdef CONFIG_MACH_APPROXIMATE_TIME
+       commpage_update_mach_approximate_time(processor->last_dispatch);
+#endif
+
+       thread->last_run_time = processor->last_dispatch;
+       thread_timer_event(processor->last_dispatch, &processor->idle_thread->system_timer);
        PROCESSOR_DATA(processor, kernel_timer) = &processor->idle_thread->system_timer;
 
        /*
         *      Cancel the quantum timer while idling.
         */
        timer_call_cancel(&processor->quantum_timer);
-       processor->timeslice = 0;
+       processor->first_timeslice = FALSE;
 
        (*thread->sched_call)(SCHED_CALL_BLOCK, thread);
 
-       thread_tell_urgency(THREAD_URGENCY_NONE, 0, 0);
+       thread_tell_urgency(THREAD_URGENCY_NONE, 0, 0, 0, NULL);
 
        /*
         *      Enable interrupts and perform idling activities.  No
@@ -1799,23 +1985,6 @@ thread_select_idle(
 
        thread_lock(thread);
 
-       /*
-        * If we idled in place, simulate a context switch back
-        * to the original priority of the thread so that the
-        * platform layer cannot distinguish this from a true
-        * switch to the idle thread.
-        */
-       if (thread->sched_mode == TH_MODE_REALTIME)
-               thread_tell_urgency(THREAD_URGENCY_REAL_TIME, thread->realtime.period, thread->realtime.deadline);
-       /* Identify non-promoted threads which have requested a
-        * "background" priority.
-        */
-       else if ((thread->sched_pri <= MAXPRI_THROTTLE) &&
-                        (thread->priority <= MAXPRI_THROTTLE))
-               thread_tell_urgency(THREAD_URGENCY_BACKGROUND, thread->sched_pri, thread->priority);
-       else
-               thread_tell_urgency(THREAD_URGENCY_NORMAL, thread->sched_pri, thread->priority);
-
        /*
         *      If awakened, switch to thread timer and start a new quantum.
         *      Otherwise skip; we will context switch to another thread or return here.
@@ -1826,166 +1995,89 @@ thread_select_idle(
                PROCESSOR_DATA(processor, kernel_timer) = &thread->system_timer;
 
                thread_quantum_init(thread);
-               thread->last_quantum_refill_time = processor->last_dispatch;
-
-               processor->quantum_end = processor->last_dispatch + thread->current_quantum;
-               timer_call_enter1(&processor->quantum_timer, thread, processor->quantum_end, TIMER_CALL_CRITICAL);
-               processor->timeslice = 1;
+               processor->quantum_end = processor->last_dispatch + thread->quantum_remaining;
+               timer_call_enter1(&processor->quantum_timer, thread, processor->quantum_end, TIMER_CALL_SYS_CRITICAL | TIMER_CALL_LOCAL);
+               processor->first_timeslice = TRUE;
 
                thread->computation_epoch = processor->last_dispatch;
        }
 
        thread->state &= ~TH_IDLE;
 
-       sched_run_incr();
-       if (thread->sched_mode == TH_MODE_TIMESHARE)
-               sched_share_incr();
-
-       return (new_thread);
-}
-#endif /* CONFIG_SCHED_IDLE_IN_PLACE */
-
-#if defined(CONFIG_SCHED_TRADITIONAL) 
-static thread_t
-sched_traditional_choose_thread(
-                                                               processor_t             processor,
-                                                               int                             priority)
-{
-       thread_t thread;
-       
-       thread = choose_thread(processor, runq_for_processor(processor), priority);
-       if (thread != THREAD_NULL) {
-               runq_consider_decr_bound_count(processor, thread);
-       }
-       
-       return thread;
-}
-
-#endif /* defined(CONFIG_SCHED_TRADITIONAL)  */
-
-#if defined(CONFIG_SCHED_TRADITIONAL) || defined(CONFIG_SCHED_FIXEDPRIORITY)
-
-/*
- *     choose_thread:
- *
- *     Locate a thread to execute from the processor run queue
- *     and return it.  Only choose a thread with greater or equal
- *     priority.
- *
- *     Associated pset must be locked.  Returns THREAD_NULL
- *     on failure.
- */
-thread_t
-choose_thread(
-       processor_t             processor,
-       run_queue_t             rq,
-       int                             priority)
-{
-       queue_t                 queue = rq->queues + rq->highq;
-       int                             pri = rq->highq, count = rq->count;
-       thread_t                thread;
-
-       while (count > 0 && pri >= priority) {
-               thread = (thread_t)queue_first(queue);
-               while (!queue_end(queue, (queue_entry_t)thread)) {
-                       if (thread->bound_processor == PROCESSOR_NULL ||
-                                                       thread->bound_processor == processor) {
-                               remqueue((queue_entry_t)thread);
-
-                               thread->runq = PROCESSOR_NULL;
-                               SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count);
-                               rq->count--;
-                               if (SCHED(priority_is_urgent)(pri)) {
-                                       rq->urgency--; assert(rq->urgency >= 0);
-                               }
-                               if (queue_empty(queue)) {
-                                       if (pri != IDLEPRI)
-                                               clrbit(MAXPRI - pri, rq->bitmap);
-                                       rq->highq = MAXPRI - ffsbit(rq->bitmap);
-                               }
+       urgency = thread_get_urgency(thread, &arg1, &arg2);
 
-                               return (thread);
-                       }
-                       count--;
+       thread_tell_urgency(urgency, arg1, arg2, 0, new_thread);
 
-                       thread = (thread_t)queue_next((queue_entry_t)thread);
-               }
+       sched_run_incr(thread);
+       if (thread->sched_mode == TH_MODE_TIMESHARE) {
+               sched_share_incr(thread);
 
-               queue--; pri--;
+               if (thread->sched_flags & TH_SFLAG_THROTTLED)
+                       sched_background_incr(thread);
        }
 
-       return (THREAD_NULL);
+       return (new_thread);
 }
-
-#endif /* defined(CONFIG_SCHED_TRADITIONAL) || defined(CONFIG_SCHED_FIXEDPRIORITY) */
+#endif /* CONFIG_SCHED_IDLE_IN_PLACE */
 
 /*
- *     Perform a context switch and start executing the new thread.
+ * thread_invoke
  *
- *     Returns FALSE on failure, and the thread is re-dispatched.
+ * Called at splsched with neither thread locked.
  *
- *     Called at splsched.
+ * Perform a context switch and start executing the new thread.
+ *
+ * Returns FALSE when the context switch didn't happen.
+ * The reference to the new thread is still consumed.
+ *
+ * "self" is what is currently running on the processor,
+ * "thread" is the new thread to context switch to
+ * (which may be the same thread in some cases)
  */
-
-#define funnel_release_check(thread, debug)                            \
-MACRO_BEGIN                                                                                            \
-       if ((thread)->funnel_state & TH_FN_OWNED) {                     \
-               (thread)->funnel_state = TH_FN_REFUNNEL;                \
-               KERNEL_DEBUG(0x603242c | DBG_FUNC_NONE,                 \
-                       (thread)->funnel_lock, (debug), 0, 0, 0);       \
-               funnel_unlock((thread)->funnel_lock);                   \
-       }                                                                                                       \
-MACRO_END
-
-#define funnel_refunnel_check(thread, debug)                           \
-MACRO_BEGIN                                                                                                    \
-       if ((thread)->funnel_state & TH_FN_REFUNNEL) {                  \
-               kern_return_t   result = (thread)->wait_result;         \
-                                                                                                                       \
-               (thread)->funnel_state = 0;                                                     \
-               KERNEL_DEBUG(0x6032428 | DBG_FUNC_NONE,                         \
-                       (thread)->funnel_lock, (debug), 0, 0, 0);               \
-               funnel_lock((thread)->funnel_lock);                                     \
-               KERNEL_DEBUG(0x6032430 | DBG_FUNC_NONE,                         \
-                       (thread)->funnel_lock, (debug), 0, 0, 0);               \
-               (thread)->funnel_state = TH_FN_OWNED;                           \
-               (thread)->wait_result = result;                                         \
-       }                                                                                                               \
-MACRO_END
-
 static boolean_t
 thread_invoke(
-       register thread_t       self,
-       register thread_t       thread,
+       thread_t                        self,
+       thread_t                        thread,
        ast_t                           reason)
 {
-       thread_continue_t       continuation = self->continuation;
-       void                            *parameter = self->parameter;
-       processor_t                     processor;
-
-       if (get_preemption_level() != 0) {
+       if (__improbable(get_preemption_level() != 0)) {
                int pl = get_preemption_level();
                panic("thread_invoke: preemption_level %d, possible cause: %s",
                    pl, (pl < 0 ? "unlocking an unlocked mutex or spinlock" :
                        "blocking while holding a spinlock, or within interrupt context"));
        }
 
+       thread_continue_t       continuation = self->continuation;
+       void                    *parameter   = self->parameter;
+       processor_t             processor;
+
+       uint64_t                ctime = mach_absolute_time();
+
+#ifdef CONFIG_MACH_APPROXIMATE_TIME
+       commpage_update_mach_approximate_time(ctime);
+#endif
+
+#if defined(CONFIG_SCHED_TIMESHARE_CORE)
+       sched_timeshare_consider_maintenance(ctime);
+#endif
+
        assert(self == current_thread());
+       assert(self->runq == PROCESSOR_NULL);
+       assert((self->state & (TH_RUN|TH_TERMINATE2)) == TH_RUN);
 
-       /*
-        * Mark thread interruptible.
-        */
        thread_lock(thread);
-       thread->state &= ~TH_UNINT;
 
-#if DEBUG
-       assert(thread_runnable(thread));
-#endif
+       assert((thread->state & (TH_RUN|TH_WAIT|TH_UNINT|TH_TERMINATE|TH_TERMINATE2)) == TH_RUN);
+       assert(thread->bound_processor == PROCESSOR_NULL || thread->bound_processor == current_processor());
+       assert(thread->runq == PROCESSOR_NULL);
 
-       /*
-        * Allow time constraint threads to hang onto
-        * a stack.
-        */
+       /* Reload precise timing global policy to thread-local policy */
+       thread->precise_user_kernel_time = use_precise_user_kernel_time(thread);
+
+       /* Update SFI class based on other factors */
+       thread->sfi_class = sfi_thread_classify(thread);
+
+       /* Allow realtime threads to hang onto a stack. */
        if ((self->sched_mode == TH_MODE_REALTIME) && !self->reserved_stack)
                self->reserved_stack = self->kernel_stack;
 
@@ -2009,6 +2101,7 @@ thread_invoke(
                        processor->active_thread = thread;
                        processor->current_pri = thread->sched_pri;
                        processor->current_thmode = thread->sched_mode;
+                       processor->current_sfi_class = thread->sfi_class;
                        if (thread->last_processor != processor && thread->last_processor != NULL) {
                                if (thread->last_processor->processor_set != processor->processor_set)
                                        thread->ps_switch++;
@@ -2017,20 +2110,32 @@ thread_invoke(
                        thread->last_processor = processor;
                        thread->c_switch++;
                        ast_context(thread);
+
                        thread_unlock(thread);
 
                        self->reason = reason;
 
-                       processor->last_dispatch = mach_absolute_time();
-                       self->last_run_time = processor->last_dispatch;
-                       thread_timer_event(processor->last_dispatch, &thread->system_timer);
+                       processor->last_dispatch = ctime;
+                       self->last_run_time = ctime;
+                       thread_timer_event(ctime, &thread->system_timer);
                        PROCESSOR_DATA(processor, kernel_timer) = &thread->system_timer;
+
+                       /*
+                        * Since non-precise user/kernel time doesn't update the state timer
+                        * during privilege transitions, synthesize an event now.
+                        */
+                       if (!thread->precise_user_kernel_time) {
+                               timer_switch(PROCESSOR_DATA(processor, current_state),
+                                                       ctime,
+                                                        PROCESSOR_DATA(processor, current_state));
+                       }
        
-                       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_STACK_HANDOFF)|DBG_FUNC_NONE,
-                                                                               self->reason, (uintptr_t)thread_tid(thread), self->sched_pri, thread->sched_pri, 0);
+                       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                               MACHDBG_CODE(DBG_MACH_SCHED, MACH_STACK_HANDOFF)|DBG_FUNC_NONE,
+                               self->reason, (uintptr_t)thread_tid(thread), self->sched_pri, thread->sched_pri, 0);
 
-                       if ((thread->chosen_processor != processor) && (thread->chosen_processor != NULL)) {
-                               KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_MOVED)|DBG_FUNC_NONE,
+                       if ((thread->chosen_processor != processor) && (thread->chosen_processor != PROCESSOR_NULL)) {
+                               SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_MOVED)|DBG_FUNC_NONE,
                                                (uintptr_t)thread_tid(thread), (uintptr_t)thread->chosen_processor->cpu_id, 0, 0, 0);
                        }
 
@@ -2041,6 +2146,9 @@ thread_invoke(
                        TLOG(1, "thread_invoke: calling stack_handoff\n");
                        stack_handoff(self, thread);
 
+                       /* 'self' is now off core */
+                       assert(thread == current_thread());
+
                        DTRACE_SCHED(on__cpu);
 
                        thread_dispatch(self, thread);
@@ -2049,7 +2157,6 @@ thread_invoke(
 
                        counter(c_thread_invoke_hits++);
 
-                       funnel_refunnel_check(thread, 2);
                        (void) spllo();
 
                        assert(continuation);
@@ -2060,21 +2167,21 @@ thread_invoke(
                        /* same thread but with continuation */
                        ast_context(self);
                        counter(++c_thread_invoke_same);
+
                        thread_unlock(self);
 
-                       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED) | DBG_FUNC_NONE,
-                                                               self->reason, (uintptr_t)thread_tid(thread), self->sched_pri, thread->sched_pri, 0);
+                       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                               MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED) | DBG_FUNC_NONE,
+                               self->reason, (uintptr_t)thread_tid(thread), self->sched_pri, thread->sched_pri, 0);
 
                        self->continuation = self->parameter = NULL;
 
-                       funnel_refunnel_check(self, 3);
                        (void) spllo();
 
                        call_continuation(continuation, parameter, self->wait_result);
                        /*NOTREACHED*/
                }
-       }
-       else {
+       } else {
                /*
                 * Check that the other thread has a stack
                 */
@@ -2086,14 +2193,14 @@ need_stack:
                                thread_stack_enqueue(thread);
                                return (FALSE);
                        }
-               }
-               else if (thread == self) {
+               } else if (thread == self) {
                        ast_context(self);
                        counter(++c_thread_invoke_same);
                        thread_unlock(self);
 
-                       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED) | DBG_FUNC_NONE,
-                                                               self->reason, (uintptr_t)thread_tid(thread), self->sched_pri, thread->sched_pri, 0);
+                       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                               MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED) | DBG_FUNC_NONE,
+                               self->reason, (uintptr_t)thread_tid(thread), self->sched_pri, thread->sched_pri, 0);
 
                        return (TRUE);
                }
@@ -2106,6 +2213,7 @@ need_stack:
        processor->active_thread = thread;
        processor->current_pri = thread->sched_pri;
        processor->current_thmode = thread->sched_mode;
+       processor->current_sfi_class = thread->sfi_class;
        if (thread->last_processor != processor && thread->last_processor != NULL) {
                if (thread->last_processor->processor_set != processor->processor_set)
                        thread->ps_switch++;
@@ -2114,23 +2222,34 @@ need_stack:
        thread->last_processor = processor;
        thread->c_switch++;
        ast_context(thread);
+
        thread_unlock(thread);
 
        counter(c_thread_invoke_csw++);
 
-       assert(self->runq == PROCESSOR_NULL);
        self->reason = reason;
 
-       processor->last_dispatch = mach_absolute_time();
-       self->last_run_time = processor->last_dispatch;
-       thread_timer_event(processor->last_dispatch, &thread->system_timer);
+       processor->last_dispatch = ctime;
+       self->last_run_time = ctime;
+       thread_timer_event(ctime, &thread->system_timer);
        PROCESSOR_DATA(processor, kernel_timer) = &thread->system_timer;
 
-       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED) | DBG_FUNC_NONE,
-                                                       self->reason, (uintptr_t)thread_tid(thread), self->sched_pri, thread->sched_pri, 0);
+       /*
+        * Since non-precise user/kernel time doesn't update the state timer
+        * during privilege transitions, synthesize an event now.
+        */
+       if (!thread->precise_user_kernel_time) {
+               timer_switch(PROCESSOR_DATA(processor, current_state),
+                                       ctime,
+                                        PROCESSOR_DATA(processor, current_state));
+       }
+
+       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+               MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED) | DBG_FUNC_NONE,
+               self->reason, (uintptr_t)thread_tid(thread), self->sched_pri, thread->sched_pri, 0);
 
        if ((thread->chosen_processor != processor) && (thread->chosen_processor != NULL)) {
-               KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_MOVED)|DBG_FUNC_NONE,
+               SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_MOVED)|DBG_FUNC_NONE,
                                (uintptr_t)thread_tid(thread), (uintptr_t)thread->chosen_processor->cpu_id, 0, 0, 0);
        }
 
@@ -2142,8 +2261,20 @@ need_stack:
         * This is where we actually switch register context,
         * and address space if required.  We will next run
         * as a result of a subsequent context switch.
+        *
+        * Once registers are switched and the processor is running "thread",
+        * the stack variables and non-volatile registers will contain whatever
+        * was there the last time that thread blocked. No local variables should
+        * be used after this point, except for the special case of "thread", which
+        * the platform layer returns as the previous thread running on the processor
+        * via the function call ABI as a return register, and "self", which may have
+        * been stored on the stack or a non-volatile register, but a stale idea of
+        * what was on the CPU is newly-accurate because that thread is again
+        * running on the CPU.
         */
+       assert(continuation == self->continuation);
        thread = machine_switch_context(self, continuation, thread);
+       assert(self == current_thread());
        TLOG(1,"thread_invoke: returning machine_switch_context: self %p continuation %p thread %p\n", self, continuation, thread);
 
        DTRACE_SCHED(on__cpu);
@@ -2156,7 +2287,6 @@ need_stack:
        if (continuation) {
                self->continuation = self->parameter = NULL;
 
-               funnel_refunnel_check(self, 3);
                (void) spllo();
 
                call_continuation(continuation, parameter, self->wait_result);
@@ -2166,6 +2296,105 @@ need_stack:
        return (TRUE);
 }
 
+#if defined(CONFIG_SCHED_DEFERRED_AST)
+/*
+ *     pset_cancel_deferred_dispatch:
+ *
+ *     Cancels all ASTs that we can cancel for the given processor set
+ *     if the current processor is running the last runnable thread in the
+ *     system.
+ *
+ *     This function assumes the current thread is runnable.  This must
+ *     be called with the pset unlocked.
+ */
+static void
+pset_cancel_deferred_dispatch(
+       processor_set_t         pset,
+       processor_t             processor)
+{
+       processor_t             active_processor = NULL;
+       uint32_t                sampled_sched_run_count;
+
+       pset_lock(pset);
+       sampled_sched_run_count = (volatile uint32_t) sched_run_count;
+
+       /*
+        * If we have emptied the run queue, and our current thread is runnable, we
+        * should tell any processors that are still DISPATCHING that they will
+        * probably not have any work to do.  In the event that there are no
+        * pending signals that we can cancel, this is also uninteresting.
+        *
+        * In the unlikely event that another thread becomes runnable while we are
+        * doing this (sched_run_count is atomically updated, not guarded), the
+        * codepath making it runnable SHOULD (a dangerous word) need the pset lock
+        * in order to dispatch it to a processor in our pset.  So, the other
+        * codepath will wait while we squash all cancelable ASTs, get the pset
+        * lock, and then dispatch the freshly runnable thread.  So this should be
+        * correct (we won't accidentally have a runnable thread that hasn't been
+        * dispatched to an idle processor), if not ideal (we may be restarting the
+        * dispatch process, which could have some overhead).
+        *
+        */
+       if ((sampled_sched_run_count == 1) &&
+           (pset->pending_deferred_AST_cpu_mask)) {
+               qe_foreach_element_safe(active_processor, &pset->active_queue, processor_queue) {
+                       /*
+                        * If a processor is DISPATCHING, it could be because of
+                        * a cancelable signal.
+                        *
+                        * IF the processor is not our
+                        * current processor (the current processor should not
+                        * be DISPATCHING, so this is a bit paranoid), AND there
+                        * is a cancelable signal pending on the processor, AND
+                        * there is no non-cancelable signal pending (as there is
+                        * no point trying to backtrack on bringing the processor
+                        * up if a signal we cannot cancel is outstanding), THEN
+                        * it should make sense to roll back the processor state
+                        * to the IDLE state.
+                        *
+                        * If the racey nature of this approach (as the signal
+                        * will be arbitrated by hardware, and can fire as we
+                        * roll back state) results in the core responding
+                        * despite being pushed back to the IDLE state, it
+                        * should be no different than if the core took some
+                        * interrupt while IDLE.
+                        */
+                       if ((active_processor->state == PROCESSOR_DISPATCHING) &&
+                           (pset->pending_deferred_AST_cpu_mask & (1ULL << active_processor->cpu_id)) &&
+                           (!(pset->pending_AST_cpu_mask & (1ULL << active_processor->cpu_id))) &&
+                           (active_processor != processor)) {
+                               /*
+                                * Squash all of the processor state back to some
+                                * reasonable facsimile of PROCESSOR_IDLE.
+                                *
+                                * TODO: What queue policy do we actually want here?
+                                * We want to promote selection of a good processor
+                                * to run on.  Do we want to enqueue at the head?
+                                * The tail?  At the (relative) old position in the
+                                * queue?  Or something else entirely?
+                                */
+                               re_queue_head(&pset->idle_queue, (queue_entry_t)active_processor);
+
+                               assert(active_processor->next_thread == THREAD_NULL);
+
+                               active_processor->current_pri = IDLEPRI;
+                               active_processor->current_thmode = TH_MODE_FIXED;
+                               active_processor->current_sfi_class = SFI_CLASS_KERNEL;
+                               active_processor->deadline = UINT64_MAX;
+                               active_processor->state = PROCESSOR_IDLE;
+                               pset->pending_deferred_AST_cpu_mask &= ~(1U << active_processor->cpu_id);
+                               machine_signal_idle_cancel(active_processor);
+                       }
+
+               }
+       }
+
+       pset_unlock(pset);
+}
+#else
+/* We don't support deferred ASTs; everything is candycanes and sunshine. */
+#endif
+
 /*
  *     thread_dispatch:
  *
@@ -2174,6 +2403,9 @@ need_stack:
  *     special actions.  Update quantum for other thread and begin
  *     the quantum for ourselves.
  *
+ *      "thread" is the old thread that we have switched away from.
+ *      "self" is the new current thread that we have context switched to
+ *
  *     Called at splsched.
  */
 void
@@ -2183,6 +2415,10 @@ thread_dispatch(
 {
        processor_t             processor = self->last_processor;
 
+       assert(processor == current_processor());
+       assert(self == current_thread());
+       assert(thread != self);
+
        if (thread != THREAD_NULL) {
                /*
                 *      If blocked at a continuation, discard
@@ -2191,40 +2427,72 @@ thread_dispatch(
                if (thread->continuation != NULL && thread->kernel_stack != 0)
                        stack_free(thread);
 
-               if (!(thread->state & TH_IDLE)) {
+               if (thread->state & TH_IDLE) {
+                       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                               MACHDBG_CODE(DBG_MACH_SCHED,MACH_DISPATCH) | DBG_FUNC_NONE,
+                               (uintptr_t)thread_tid(thread), 0, thread->state, sched_run_count, 0);
+               } else {
+                       int64_t consumed;
+                       int64_t remainder = 0;
+
+                       if (processor->quantum_end > processor->last_dispatch)
+                               remainder = processor->quantum_end -
+                                   processor->last_dispatch;
+
+                       consumed = thread->quantum_remaining - remainder;
+
+                       if ((thread->reason & AST_LEDGER) == 0) {
+                               /*
+                                * Bill CPU time to both the task and
+                                * the individual thread.
+                                */
+                               ledger_credit(thread->t_ledger,
+                                   task_ledgers.cpu_time, consumed);
+                               ledger_credit(thread->t_threadledger,
+                                   thread_ledgers.cpu_time, consumed);
+#ifdef CONFIG_BANK
+                               if (thread->t_bankledger) {
+                                       ledger_credit(thread->t_bankledger,
+                                               bank_ledgers.cpu_time,
+                                               (consumed - thread->t_deduct_bank_ledger_time));
+
+                               }
+                               thread->t_deduct_bank_ledger_time =0;
+#endif
+                       }
+
                        wake_lock(thread);
                        thread_lock(thread);
 
                        /*
                         *      Compute remainder of current quantum.
                         */
-                       if (    first_timeslice(processor)                                                      &&
-                                       processor->quantum_end > processor->last_dispatch               )
-                               thread->current_quantum = (uint32_t)(processor->quantum_end - processor->last_dispatch);
+                       if (processor->first_timeslice &&
+                           processor->quantum_end > processor->last_dispatch)
+                               thread->quantum_remaining = (uint32_t)remainder;
                        else
-                               thread->current_quantum = 0;
+                               thread->quantum_remaining = 0;
 
                        if (thread->sched_mode == TH_MODE_REALTIME) {
                                /*
                                 *      Cancel the deadline if the thread has
                                 *      consumed the entire quantum.
                                 */
-                               if (thread->current_quantum == 0) {
+                               if (thread->quantum_remaining == 0) {
                                        thread->realtime.deadline = UINT64_MAX;
-                                       thread->reason |= AST_QUANTUM;
                                }
                        } else {
-#if defined(CONFIG_SCHED_TRADITIONAL)
+#if defined(CONFIG_SCHED_TIMESHARE_CORE)
                                /*
                                 *      For non-realtime threads treat a tiny
                                 *      remaining quantum as an expired quantum
                                 *      but include what's left next time.
                                 */
-                               if (thread->current_quantum < min_std_quantum) {
+                               if (thread->quantum_remaining < min_std_quantum) {
                                        thread->reason |= AST_QUANTUM;
-                                       thread->current_quantum += std_quantum;
+                                       thread->quantum_remaining += SCHED(initial_quantum_size)(thread);
                                }
-#endif
+#endif /* CONFIG_SCHED_TIMESHARE_CORE */
                        }
 
                        /*
@@ -2232,35 +2500,84 @@ thread_dispatch(
                         *      take the remainder of the quantum.
                         */
                        if ((thread->reason & (AST_HANDOFF|AST_QUANTUM)) == AST_HANDOFF) {
-                               self->current_quantum = thread->current_quantum;
+                               self->quantum_remaining = thread->quantum_remaining;
                                thread->reason |= AST_QUANTUM;
-                               thread->current_quantum = 0;
+                               thread->quantum_remaining = 0;
+                       } else {
+#if defined(CONFIG_SCHED_MULTIQ)
+                               if (SCHED(sched_groups_enabled) &&
+                                   thread->sched_group == self->sched_group) {
+                                       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                                           MACHDBG_CODE(DBG_MACH_SCHED, MACH_QUANTUM_HANDOFF),
+                                           self->reason, (uintptr_t)thread_tid(thread),
+                                           self->quantum_remaining, thread->quantum_remaining, 0);
+
+                                       self->quantum_remaining = thread->quantum_remaining;
+                                       thread->quantum_remaining = 0;
+                                       /* Don't set AST_QUANTUM here - old thread might still want to preempt someone else */
+                               }
+#endif /* defined(CONFIG_SCHED_MULTIQ) */
                        }
 
                        thread->computation_metered += (processor->last_dispatch - thread->computation_epoch);
 
+                       if ((thread->rwlock_count != 0) && !(LcksOpts & disLkRWPrio)) {
+                               integer_t priority;
+
+                               priority = thread->sched_pri;
+
+                               if (priority < thread->base_pri)
+                                       priority = thread->base_pri;
+                               if (priority < BASEPRI_BACKGROUND)
+                                       priority = BASEPRI_BACKGROUND;
+
+                               if ((thread->sched_pri < priority) || !(thread->sched_flags & TH_SFLAG_RW_PROMOTED)) {
+                                       KERNEL_DEBUG_CONSTANT(
+                                               MACHDBG_CODE(DBG_MACH_SCHED, MACH_RW_PROMOTE) | DBG_FUNC_NONE,
+                                               (uintptr_t)thread_tid(thread), thread->sched_pri, thread->base_pri, priority, 0);
+
+                                       thread->sched_flags |= TH_SFLAG_RW_PROMOTED;
+
+                                       if (thread->sched_pri < priority)
+                                               set_sched_pri(thread, priority);
+                               }
+                       }
+
                        if (!(thread->state & TH_WAIT)) {
                                /*
-                                *      Still running.
+                                *      Still runnable.
                                 */
+                               thread->last_made_runnable_time = mach_approximate_time();
+
+                               machine_thread_going_off_core(thread, FALSE);
+
                                if (thread->reason & AST_QUANTUM)
                                        thread_setrun(thread, SCHED_TAILQ);
-                               else
-                               if (thread->reason & AST_PREEMPT)
+                               else if (thread->reason & AST_PREEMPT)
                                        thread_setrun(thread, SCHED_HEADQ);
                                else
                                        thread_setrun(thread, SCHED_PREEMPT | SCHED_TAILQ);
 
-                               thread->reason = AST_NONE;
+                               KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                                       MACHDBG_CODE(DBG_MACH_SCHED,MACH_DISPATCH) | DBG_FUNC_NONE,
+                                       (uintptr_t)thread_tid(thread), thread->reason, thread->state, sched_run_count, 0);
+
+                               if (thread->wake_active) {
+                                       thread->wake_active = FALSE;
+                                       thread_unlock(thread);
+
+                                       thread_wakeup(&thread->wake_active);
+                               } else {
+                                       thread_unlock(thread);
+                               }
 
-                               thread_unlock(thread);
                                wake_unlock(thread);
-                       }
-                       else {
+                       } else {
                                /*
                                 *      Waiting.
                                 */
                                boolean_t should_terminate = FALSE;
+                               uint32_t new_run_count;
 
                                /* Only the first call to thread_dispatch
                                 * after explicit termination should add
@@ -2272,10 +2589,30 @@ thread_dispatch(
                                }
 
                                thread->state &= ~TH_RUN;
+                               thread->last_made_runnable_time = ~0ULL;
+                               thread->chosen_processor = PROCESSOR_NULL;
+
+                               if (thread->sched_mode == TH_MODE_TIMESHARE) {
+                                       if (thread->sched_flags & TH_SFLAG_THROTTLED)
+                                               sched_background_decr(thread);
+
+                                       sched_share_decr(thread);
+                               }
+                               new_run_count = sched_run_decr(thread);
+
+#if CONFIG_SCHED_SFI
+                               if ((thread->state & (TH_WAIT | TH_TERMINATE)) == TH_WAIT) {
+                                       if (thread->reason & AST_SFI) {
+                                               thread->wait_sfi_begin_time = processor->last_dispatch;
+                                       }
+                               }
+#endif
 
-                               if (thread->sched_mode == TH_MODE_TIMESHARE)
-                                       sched_share_decr();
-                               sched_run_decr();
+                               machine_thread_going_off_core(thread, should_terminate);
+
+                               KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                                       MACHDBG_CODE(DBG_MACH_SCHED,MACH_DISPATCH) | DBG_FUNC_NONE,
+                                       (uintptr_t)thread_tid(thread), thread->reason, thread->state, new_run_count, 0);
 
                                (*thread->sched_call)(SCHED_CALL_BLOCK, thread);
 
@@ -2284,9 +2621,9 @@ thread_dispatch(
                                        thread_unlock(thread);
 
                                        thread_wakeup(&thread->wake_active);
-                               }
-                               else
+                               } else {
                                        thread_unlock(thread);
+                               }
 
                                wake_unlock(thread);
 
@@ -2296,48 +2633,71 @@ thread_dispatch(
                }
        }
 
+       /* Update (new) current thread and reprogram quantum timer */
+       thread_lock(self);
        if (!(self->state & TH_IDLE)) {
+               uint64_t        arg1, arg2;
+               int             urgency;
+               uint64_t                latency;
 
-               if (self->sched_mode == TH_MODE_REALTIME)
-                       thread_tell_urgency(THREAD_URGENCY_REAL_TIME, self->realtime.period, self->realtime.deadline);
-               /* Identify non-promoted threads which have requested a
-                * "background" priority.
-                */
-               else if ((self->sched_pri <= MAXPRI_THROTTLE) &&
-                       (self->priority <= MAXPRI_THROTTLE))
-                       thread_tell_urgency(THREAD_URGENCY_BACKGROUND, self->sched_pri, self->priority);
-               else
-                       thread_tell_urgency(THREAD_URGENCY_NORMAL, self->sched_pri, self->priority);
+#if CONFIG_SCHED_SFI
+               ast_t                   new_ast;
+
+               new_ast = sfi_thread_needs_ast(self, NULL);
+
+               if (new_ast != AST_NONE) {
+                       ast_on(new_ast);
+               }
+#endif
+
+               assert(processor->last_dispatch >= self->last_made_runnable_time);
+               latency = processor->last_dispatch - self->last_made_runnable_time;
+
+               urgency = thread_get_urgency(self, &arg1, &arg2);
+
+               thread_tell_urgency(urgency, arg1, arg2, latency, self);
+
+               machine_thread_going_on_core(self, urgency, latency);
+               
                /*
                 *      Get a new quantum if none remaining.
                 */
-               if (self->current_quantum == 0) {
+               if (self->quantum_remaining == 0) {
                        thread_quantum_init(self);
-                       self->last_quantum_refill_time = processor->last_dispatch;
                }
 
                /*
                 *      Set up quantum timer and timeslice.
                 */
-               processor->quantum_end = (processor->last_dispatch + self->current_quantum);
-               timer_call_enter1(&processor->quantum_timer, self, processor->quantum_end, TIMER_CALL_CRITICAL);
+               processor->quantum_end = processor->last_dispatch + self->quantum_remaining;
+               timer_call_enter1(&processor->quantum_timer, self, processor->quantum_end, TIMER_CALL_SYS_CRITICAL | TIMER_CALL_LOCAL);
 
-               processor->timeslice = 1;
-
-               self->computation_epoch = processor->last_dispatch;
-       }
-       else {
+               processor->first_timeslice = TRUE;
+       } else {
                timer_call_cancel(&processor->quantum_timer);
-               processor->timeslice = 0;
+               processor->first_timeslice = FALSE;
 
-               thread_tell_urgency(THREAD_URGENCY_NONE, 0, 0);
+               thread_tell_urgency(THREAD_URGENCY_NONE, 0, 0, 0, self);
+               machine_thread_going_on_core(self, THREAD_URGENCY_NONE, 0);
        }
-}
 
-#include <libkern/OSDebug.h>
+       self->computation_epoch = processor->last_dispatch;
+       self->reason = AST_NONE;
+
+       thread_unlock(self);
 
-uint32_t       kdebug_thread_block = 0;
+#if defined(CONFIG_SCHED_DEFERRED_AST)
+       /*
+        * TODO: Can we state that redispatching our old thread is also
+        * uninteresting?
+        */
+       if ((((volatile uint32_t)sched_run_count) == 1) &&
+           !(self->state & TH_IDLE)) {
+               pset_cancel_deferred_dispatch(processor->processor_set, processor);
+       }
+#endif
 
+}
 
 /*
  *     thread_block_reason:
@@ -2358,23 +2718,20 @@ thread_block_reason(
        void                            *parameter,
        ast_t                           reason)
 {
-       register thread_t               self = current_thread();
-       register processor_t    processor;
-       register thread_t               new_thread;
-       spl_t                                   s;
+       thread_t        self = current_thread();
+       processor_t     processor;
+       thread_t        new_thread;
+       spl_t           s;
 
        counter(++c_thread_block_calls);
 
        s = splsched();
 
-       if (!(reason & AST_PREEMPT))
-               funnel_release_check(self, 2);
-
        processor = current_processor();
 
        /* If we're explicitly yielding, force a subsequent quantum */
        if (reason & AST_YIELD)
-               processor->timeslice = 0;
+               processor->first_timeslice = FALSE;
 
        /* We're handling all scheduling AST's */
        ast_off(AST_SCHEDULING);
@@ -2382,22 +2739,18 @@ thread_block_reason(
        self->continuation = continuation;
        self->parameter = parameter;
 
-       if (__improbable(kdebug_thread_block && kdebug_enable && self->state != TH_RUN)) {
-               uint32_t        bt[8];
-
-               OSBacktrace((void **)&bt[0], 8);
-
-               KERNEL_DEBUG_CONSTANT(0x140004c | DBG_FUNC_START, bt[0], bt[1], bt[2], bt[3], 0);
-               KERNEL_DEBUG_CONSTANT(0x140004c | DBG_FUNC_END, bt[4], bt[5], bt[6], bt[7], 0);
+       if (self->state & ~(TH_RUN | TH_IDLE)) {
+               KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                       MACHDBG_CODE(DBG_MACH_SCHED,MACH_BLOCK), 
+                       reason, VM_KERNEL_UNSLIDE(continuation), 0, 0, 0);
        }
 
        do {
                thread_lock(self);
-               new_thread = thread_select(self, processor);
+               new_thread = thread_select(self, processor, reason);
                thread_unlock(self);
        } while (!thread_invoke(self, new_thread, reason));
 
-       funnel_refunnel_check(self, 5);
        splx(s);
 
        return (self->wait_result);
@@ -2442,8 +2795,6 @@ thread_run(
 {
        ast_t           handoff = AST_HANDOFF;
 
-       funnel_release_check(self, 3);
-
        self->continuation = continuation;
        self->parameter = parameter;
 
@@ -2451,13 +2802,11 @@ thread_run(
                processor_t             processor = current_processor();
 
                thread_lock(self);
-               new_thread = thread_select(self, processor);
+               new_thread = thread_select(self, processor, AST_NONE);
                thread_unlock(self);
                handoff = AST_NONE;
        }
 
-       funnel_refunnel_check(self, 6);
-
        return (self->wait_result);
 }
 
@@ -2469,11 +2818,11 @@ thread_run(
  */
 void
 thread_continue(
-       register thread_t       thread)
+       thread_t        thread)
 {
-       register thread_t                       self = current_thread();
-       register thread_continue_t      continuation;
-       register void                           *parameter;
+       thread_t                self = current_thread();
+       thread_continue_t       continuation;
+       void                    *parameter;
 
        DTRACE_SCHED(on__cpu);
 
@@ -2484,8 +2833,6 @@ thread_continue(
 
        self->continuation = self->parameter = NULL;
 
-       funnel_refunnel_check(self, 4);
-
        if (thread != THREAD_NULL)
                (void)spllo();
 
@@ -2498,36 +2845,21 @@ void
 thread_quantum_init(thread_t thread)
 {
        if (thread->sched_mode == TH_MODE_REALTIME) {
-               thread->current_quantum = thread->realtime.computation;
+               thread->quantum_remaining = thread->realtime.computation;
        } else {
-               thread->current_quantum = SCHED(initial_quantum_size)(thread);
+               thread->quantum_remaining = SCHED(initial_quantum_size)(thread);
        }
 }
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
-static uint32_t
-sched_traditional_initial_quantum_size(thread_t thread __unused)
-{
-       return std_quantum;
-}
-
-static sched_mode_t
-sched_traditional_initial_thread_sched_mode(task_t parent_task)
+uint32_t
+sched_timeshare_initial_quantum_size(thread_t thread)
 {
-       if (parent_task == kernel_task)
-               return TH_MODE_FIXED;
+       if ((thread == THREAD_NULL) || !(thread->sched_flags & TH_SFLAG_THROTTLED))
+               return std_quantum;
        else
-               return TH_MODE_TIMESHARE;
-}
-
-static boolean_t
-sched_traditional_supports_timeshare_mode(void)
-{
-       return TRUE;
+               return bg_quantum;
 }
 
-#endif /* CONFIG_SCHED_TRADITIONAL */
-
 /*
  *     run_queue_init:
  *
@@ -2548,103 +2880,22 @@ run_queue_init(
                queue_init(&rq->queues[i]);
 }
 
-#if defined(CONFIG_SCHED_TRADITIONAL) || defined(CONFIG_SCHED_PROTO) || defined(CONFIG_SCHED_GRRR) || defined(CONFIG_SCHED_FIXEDPRIORITY)
-int
-sched_traditional_fairshare_runq_count(void)
-{
-       return fs_runq.count;
-}
-
-uint64_t
-sched_traditional_fairshare_runq_stats_count_sum(void)
-{
-       return fs_runq.runq_stats.count_sum;
-}
-
-void
-sched_traditional_fairshare_enqueue(thread_t thread)
-{
-       queue_t                         queue = &fs_runq.queue;
-       
-       simple_lock(&fs_lock);
-       
-       enqueue_tail(queue, (queue_entry_t)thread);
-       
-       thread->runq = FS_RUNQ;
-       SCHED_STATS_RUNQ_CHANGE(&fs_runq.runq_stats, fs_runq.count);
-       fs_runq.count++;
-       
-       simple_unlock(&fs_lock);        
-}
-
+/*
+ *     run_queue_dequeue:
+ *
+ *     Perform a dequeue operation on a run queue,
+ *     and return the resulting thread.
+ *
+ *     The run queue must be locked (see thread_run_queue_remove()
+ *     for more info), and not empty.
+ */
 thread_t
-sched_traditional_fairshare_dequeue(void)
+run_queue_dequeue(
+       run_queue_t             rq,
+       integer_t               options)
 {
-       thread_t thread;
-       
-       simple_lock(&fs_lock);
-       if (fs_runq.count > 0) {
-               thread = (thread_t)dequeue_head(&fs_runq.queue);
-               
-               thread->runq = PROCESSOR_NULL;
-               SCHED_STATS_RUNQ_CHANGE(&fs_runq.runq_stats, fs_runq.count);
-               fs_runq.count--;
-               
-               simple_unlock(&fs_lock);
-               
-               return (thread);
-       }
-       simple_unlock(&fs_lock);                
-
-       return THREAD_NULL;
-}
-
-boolean_t
-sched_traditional_fairshare_queue_remove(thread_t thread)
-{
-       queue_t                 q;
-
-       simple_lock(&fs_lock);
-       q = &fs_runq.queue;
-       
-       if (FS_RUNQ == thread->runq) {
-               remqueue((queue_entry_t)thread);
-               SCHED_STATS_RUNQ_CHANGE(&fs_runq.runq_stats, fs_runq.count);
-               fs_runq.count--;
-               
-               thread->runq = PROCESSOR_NULL;
-               simple_unlock(&fs_lock);
-               return (TRUE);
-       }
-       else {
-               /*
-                *      The thread left the run queue before we could
-                *      lock the run queue.
-                */
-               assert(thread->runq == PROCESSOR_NULL);
-               simple_unlock(&fs_lock);
-               return (FALSE);
-       }       
-}
-
-#endif /* defined(CONFIG_SCHED_TRADITIONAL) || defined(CONFIG_SCHED_PROTO) || defined(CONFIG_SCHED_GRRR) || defined(CONFIG_SCHED_FIXEDPRIORITY) */
-
-/*
- *     run_queue_dequeue:
- *
- *     Perform a dequeue operation on a run queue,
- *     and return the resulting thread.
- *
- *     The run queue must be locked (see thread_run_queue_remove()
- *     for more info), and not empty.
- */
-thread_t
-run_queue_dequeue(
-       run_queue_t             rq,
-       integer_t               options)
-{
-       thread_t                thread;
-       queue_t                 queue = rq->queues + rq->highq;
+       thread_t                thread;
+       queue_t                 queue = rq->queues + rq->highq;
 
        if (options & SCHED_HEADQ) {
                thread = (thread_t)dequeue_head(queue);
@@ -2693,13 +2944,12 @@ run_queue_enqueue(
                        rq->highq = thread->sched_pri;
                        result = TRUE;
                }
-       }
-       else
+       } else {
                if (options & SCHED_TAILQ)
                        enqueue_tail(queue, (queue_entry_t)thread);
                else
                        enqueue_head(queue, (queue_entry_t)thread);
-       
+       }
        if (SCHED(priority_is_urgent)(thread->sched_pri))
                rq->urgency++;
        SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count);
@@ -2739,32 +2989,27 @@ run_queue_remove(
        thread->runq = PROCESSOR_NULL;
 }
 
-/*
- *     fairshare_setrun:
- *
- *     Dispatch a thread for round-robin execution.
- *
- *     Thread must be locked.  Associated pset must
- *     be locked, and is returned unlocked.
- */
-static void
-fairshare_setrun(
-                                 processor_t                   processor,
-                                 thread_t                      thread)
+/* Assumes RT lock is not held, and acquires splsched/rt_lock itself */
+void
+rt_runq_scan(sched_update_scan_context_t scan_context)
 {
-       processor_set_t         pset = processor->processor_set;
-               
-       thread->chosen_processor = processor;
+       spl_t           s;
+       thread_t        thread;
 
-       SCHED(fairshare_enqueue)(thread);
-       
-       if (processor != current_processor())
-               machine_signal_idle(processor);
+       s = splsched();
+       rt_lock_lock();
 
-       pset_unlock(pset);
+       qe_foreach_element_safe(thread, &rt_runq.queue, links) {
+               if (thread->last_made_runnable_time < scan_context->earliest_rt_make_runnable_time) {
+                       scan_context->earliest_rt_make_runnable_time = thread->last_made_runnable_time;
+               }
+       }
 
+       rt_lock_unlock();
+       splx(s);
 }
 
+
 /*
  *     realtime_queue_insert:
  *
@@ -2778,7 +3023,7 @@ realtime_queue_insert(
        uint64_t                        deadline = thread->realtime.deadline;
        boolean_t                       preempt = FALSE;
 
-       simple_lock(&rt_lock);
+       rt_lock_lock();
 
        if (queue_empty(queue)) {
                enqueue_tail(queue, (queue_entry_t)thread);
@@ -2803,11 +3048,11 @@ realtime_queue_insert(
                insque((queue_entry_t)thread, (queue_entry_t)entry);
        }
 
-       thread->runq = RT_RUNQ;
+       thread->runq = THREAD_ON_RT_RUNQ;
        SCHED_STATS_RUNQ_CHANGE(&rt_runq.runq_stats, rt_runq.count);
        rt_runq.count++;
 
-       simple_unlock(&rt_lock);
+       rt_lock_unlock();
 
        return (preempt);
 }
@@ -2826,9 +3071,15 @@ realtime_setrun(
        thread_t                        thread)
 {
        processor_set_t         pset = processor->processor_set;
+       ast_t                           preempt;
+
+       boolean_t do_signal_idle = FALSE, do_cause_ast = FALSE;
 
        thread->chosen_processor = processor;
 
+       /* <rdar://problem/15102234> */
+       assert(thread->bound_processor == PROCESSOR_NULL);
+
        /*
         *      Dispatch directly onto idle processor.
         */
@@ -2838,65 +3089,96 @@ realtime_setrun(
                enqueue_tail(&pset->active_queue, (queue_entry_t)processor);
 
                processor->next_thread = thread;
+               processor->current_pri = thread->sched_pri;
+               processor->current_thmode = thread->sched_mode;
+               processor->current_sfi_class = thread->sfi_class;
                processor->deadline = thread->realtime.deadline;
                processor->state = PROCESSOR_DISPATCHING;
+
+               if (processor != current_processor()) {
+                       if (!(pset->pending_AST_cpu_mask & (1ULL << processor->cpu_id))) {
+                               /* cleared on exit from main processor_idle() loop */
+                               pset->pending_AST_cpu_mask |= (1ULL << processor->cpu_id);
+                               do_signal_idle = TRUE;
+                       }
+               }
                pset_unlock(pset);
 
-               if (processor != current_processor())
+               if (do_signal_idle) {
                        machine_signal_idle(processor);
+               }
                return;
        }
 
-       if (realtime_queue_insert(thread)) {
-               int prstate = processor->state;
-               if (processor == current_processor())
-                       ast_on(AST_PREEMPT | AST_URGENT);
-               else if ((prstate == PROCESSOR_DISPATCHING)  || (prstate == PROCESSOR_IDLE))
-                       machine_signal_idle(processor);
-               else
-                       cause_ast_check(processor);
+       if (processor->current_pri < BASEPRI_RTQUEUES)
+               preempt = (AST_PREEMPT | AST_URGENT);
+       else if (thread->realtime.deadline < processor->deadline)
+               preempt = (AST_PREEMPT | AST_URGENT);
+       else
+               preempt = AST_NONE;
+
+       realtime_queue_insert(thread);
+
+       if (preempt != AST_NONE) {
+               if (processor->state == PROCESSOR_IDLE) {
+                       remqueue((queue_entry_t)processor);
+                       enqueue_tail(&pset->active_queue, (queue_entry_t)processor);
+                       processor->next_thread = THREAD_NULL;
+                       processor->current_pri = thread->sched_pri;
+                       processor->current_thmode = thread->sched_mode;
+                       processor->current_sfi_class = thread->sfi_class;
+                       processor->deadline = thread->realtime.deadline;
+                       processor->state = PROCESSOR_DISPATCHING;
+                       if (processor == current_processor()) {
+                               ast_on(preempt);
+                       } else {
+                               if (!(pset->pending_AST_cpu_mask & (1ULL << processor->cpu_id))) {
+                                       /* cleared on exit from main processor_idle() loop */
+                                       pset->pending_AST_cpu_mask |= (1ULL << processor->cpu_id);
+                                       do_signal_idle = TRUE;
+                               }
+                       }
+               } else if (processor->state == PROCESSOR_DISPATCHING) {
+                       if ((processor->next_thread == THREAD_NULL) && ((processor->current_pri < thread->sched_pri) || (processor->deadline > thread->realtime.deadline))) {
+                               processor->current_pri = thread->sched_pri;
+                               processor->current_thmode = thread->sched_mode;
+                               processor->current_sfi_class = thread->sfi_class;
+                               processor->deadline = thread->realtime.deadline;
+                       }
+               } else {
+                       if (processor == current_processor()) {
+                               ast_on(preempt);
+                       } else {
+                               if (!(pset->pending_AST_cpu_mask & (1ULL << processor->cpu_id))) {
+                                       /* cleared after IPI causes csw_check() to be called */
+                                       pset->pending_AST_cpu_mask |= (1ULL << processor->cpu_id);
+                                       do_cause_ast = TRUE;
+                               }
+                       }
+               }
+       } else {
+               /* Selected processor was too busy, just keep thread enqueued and let other processors drain it naturally. */
        }
 
        pset_unlock(pset);
+
+       if (do_signal_idle) {
+               machine_signal_idle(processor);
+       } else if (do_cause_ast) {
+               cause_ast_check(processor);
+       }
 }
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
 
-static boolean_t
+#if defined(CONFIG_SCHED_TIMESHARE_CORE)
+
+boolean_t
 priority_is_urgent(int priority)
 {
        return testbit(priority, sched_preempt_pri) ? TRUE : FALSE;
 }
 
-/*
- *     processor_enqueue:
- *
- *     Enqueue thread on a processor run queue.  Thread must be locked,
- *     and not already be on a run queue.
- *
- *     Returns TRUE if a preemption is indicated based on the state
- *     of the run queue.
- *
- *     The run queue must be locked (see thread_run_queue_remove()
- *     for more info).
- */
-static boolean_t
-processor_enqueue(
-       processor_t             processor,
-       thread_t                thread,
-       integer_t               options)
-{
-       run_queue_t             rq = runq_for_processor(processor);
-       boolean_t               result;
-       
-       result = run_queue_enqueue(rq, thread, options);
-       thread->runq = processor;
-       runq_consider_incr_bound_count(processor, thread);
-
-       return (result);
-}
-
-#endif /* CONFIG_SCHED_TRADITIONAL */
+#endif /* CONFIG_SCHED_TIMESHARE_CORE */
 
 /*
  *     processor_setrun:
@@ -2915,6 +3197,10 @@ processor_setrun(
 {
        processor_set_t         pset = processor->processor_set;
        ast_t                           preempt;
+       enum { eExitIdle, eInterruptRunning, eDoNothing } ipi_action = eDoNothing;
+       enum { eNoSignal, eDoSignal, eDoDeferredSignal } do_signal_idle = eNoSignal;
+
+       boolean_t do_cause_ast = FALSE;
 
        thread->chosen_processor = processor;
 
@@ -2928,161 +3214,158 @@ processor_setrun(
                enqueue_tail(&pset->active_queue, (queue_entry_t)processor);
 
                processor->next_thread = thread;
+               processor->current_pri = thread->sched_pri;
+               processor->current_thmode = thread->sched_mode;
+               processor->current_sfi_class = thread->sfi_class;
                processor->deadline = UINT64_MAX;
                processor->state = PROCESSOR_DISPATCHING;
+
+               if (!(pset->pending_AST_cpu_mask & (1ULL << processor->cpu_id))) {
+                       /* cleared on exit from main processor_idle() loop */
+                       pset->pending_AST_cpu_mask |= (1ULL << processor->cpu_id);
+                       do_signal_idle = eDoSignal;
+               }
+
                pset_unlock(pset);
 
-               if (processor != current_processor())
+               if (do_signal_idle == eDoSignal) {
                        machine_signal_idle(processor);
+               }
+
                return;
        }
 
        /*
         *      Set preemption mode.
         */
+#if defined(CONFIG_SCHED_DEFERRED_AST)
+       /* TODO: Do we need to care about urgency (see rdar://problem/20136239)? */
+#endif
        if (SCHED(priority_is_urgent)(thread->sched_pri) && thread->sched_pri > processor->current_pri)
                preempt = (AST_PREEMPT | AST_URGENT);
        else if(processor->active_thread && thread_eager_preemption(processor->active_thread))
                preempt = (AST_PREEMPT | AST_URGENT);
-       else
-       if ((thread->sched_mode == TH_MODE_TIMESHARE) && thread->sched_pri < thread->priority)
-               preempt = AST_NONE;
-       else
+       else if ((thread->sched_mode == TH_MODE_TIMESHARE) && (thread->sched_pri < thread->base_pri)) {
+               if(SCHED(priority_is_urgent)(thread->base_pri) && thread->sched_pri > processor->current_pri) {
+                       preempt = (options & SCHED_PREEMPT)? AST_PREEMPT: AST_NONE;
+               } else {
+                       preempt = AST_NONE;
+               }
+       } else
                preempt = (options & SCHED_PREEMPT)? AST_PREEMPT: AST_NONE;
 
-       if (!SCHED(processor_enqueue)(processor, thread, options))
-               preempt = AST_NONE;
+       SCHED(processor_enqueue)(processor, thread, options);
 
        if (preempt != AST_NONE) {
-               if (processor == current_processor()) {
-                       if (csw_check(processor) != AST_NONE)
-                               ast_on(preempt);
-               }
-               else
-               if (    processor->state == PROCESSOR_IDLE || processor->state == PROCESSOR_DISPATCHING) {
-                       machine_signal_idle(processor);
-               }
-               else
-               if (    (processor->state == PROCESSOR_RUNNING          ||
+               if (processor->state == PROCESSOR_IDLE) {
+                       remqueue((queue_entry_t)processor);
+                       enqueue_tail(&pset->active_queue, (queue_entry_t)processor);
+                       processor->next_thread = THREAD_NULL;
+                       processor->current_pri = thread->sched_pri;
+                       processor->current_thmode = thread->sched_mode;
+                       processor->current_sfi_class = thread->sfi_class;
+                       processor->deadline = UINT64_MAX;
+                       processor->state = PROCESSOR_DISPATCHING;
+
+                       ipi_action = eExitIdle;
+               } else if ( processor->state == PROCESSOR_DISPATCHING) {
+                       if ((processor->next_thread == THREAD_NULL) && (processor->current_pri < thread->sched_pri)) {
+                               processor->current_pri = thread->sched_pri;
+                               processor->current_thmode = thread->sched_mode;
+                               processor->current_sfi_class = thread->sfi_class;
+                               processor->deadline = UINT64_MAX;
+                       }
+               } else if (     (processor->state == PROCESSOR_RUNNING          ||
                                 processor->state == PROCESSOR_SHUTDOWN)                &&
-                               (thread->sched_pri >= processor->current_pri    ||
-                               processor->current_thmode == TH_MODE_FAIRSHARE)) {
-                       cause_ast_check(processor);
+                               (thread->sched_pri >= processor->current_pri)) {
+                       ipi_action = eInterruptRunning;
                }
-       }
-       else
-       if (    processor->state == PROCESSOR_SHUTDOWN          &&
+       } else {
+               /*
+                * New thread is not important enough to preempt what is running, but
+                * special processor states may need special handling
+                */
+               if (processor->state == PROCESSOR_SHUTDOWN              &&
                        thread->sched_pri >= processor->current_pri     ) {
-               cause_ast_check(processor);
+                       ipi_action = eInterruptRunning;
+               } else if (     processor->state == PROCESSOR_IDLE      &&
+                                       processor != current_processor()        ) {
+                       remqueue((queue_entry_t)processor);
+                       enqueue_tail(&pset->active_queue, (queue_entry_t)processor);
+                       processor->next_thread = THREAD_NULL;
+                       processor->current_pri = thread->sched_pri;
+                       processor->current_thmode = thread->sched_mode;
+                       processor->current_sfi_class = thread->sfi_class;
+                       processor->deadline = UINT64_MAX;
+                       processor->state = PROCESSOR_DISPATCHING;
+
+                       ipi_action = eExitIdle;
+               }
        }
-       else
-       if (    processor->state == PROCESSOR_IDLE      &&
-                       processor != current_processor()        ) {
-                               machine_signal_idle(processor);
+
+       switch (ipi_action) {
+               case eDoNothing:
+                       break;
+               case eExitIdle:
+                       if (processor == current_processor()) {
+                               if (csw_check_locked(processor, pset, AST_NONE) != AST_NONE)
+                                       ast_on(preempt);
+                       } else {
+#if defined(CONFIG_SCHED_DEFERRED_AST)
+                               if (!(pset->pending_deferred_AST_cpu_mask & (1ULL << processor->cpu_id)) &&
+                                   !(pset->pending_AST_cpu_mask & (1ULL << processor->cpu_id))) {
+                                       /* cleared on exit from main processor_idle() loop */
+                                       pset->pending_deferred_AST_cpu_mask |= (1ULL << processor->cpu_id);
+                                       do_signal_idle = eDoDeferredSignal;
+                               }
+#else
+                               if (!(pset->pending_AST_cpu_mask & (1ULL << processor->cpu_id))) {
+                                       /* cleared on exit from main processor_idle() loop */
+                                       pset->pending_AST_cpu_mask |= (1ULL << processor->cpu_id);
+                                       do_signal_idle = eDoSignal;
+                               }
+#endif
+                       }
+                       break;
+               case eInterruptRunning:
+                       if (processor == current_processor()) {
+                               if (csw_check_locked(processor, pset, AST_NONE) != AST_NONE)
+                                       ast_on(preempt);
+                       } else {
+                               if (!(pset->pending_AST_cpu_mask & (1ULL << processor->cpu_id))) {
+                                       /* cleared after IPI causes csw_check() to be called */
+                                       pset->pending_AST_cpu_mask |= (1ULL << processor->cpu_id);
+                                       do_cause_ast = TRUE;
+                               }
+                       }
+                       break;
        }
 
        pset_unlock(pset);
-}
-
-#if defined(CONFIG_SCHED_TRADITIONAL)
-
-static boolean_t
-processor_queue_empty(processor_t              processor)
-{
-       return runq_for_processor(processor)->count == 0;
-       
-}
-
-static boolean_t
-sched_traditional_with_pset_runqueue_processor_queue_empty(processor_t         processor)
-{
-       processor_set_t pset = processor->processor_set;
-       int count = runq_for_processor(processor)->count;
-
-       /*
-        * The pset runq contains the count of all runnable threads
-        * for all processors in the pset. However, for threads that
-        * are bound to another processor, the current "processor"
-        * is not eligible to execute the thread. So we only
-        * include bound threads that our bound to the current
-        * "processor". This allows the processor to idle when the
-        * count of eligible threads drops to 0, even if there's
-        * a runnable thread bound to a different processor in the
-        * shared runq.
-        */
-
-       count -= pset->pset_runq_bound_count;
-       count += processor->runq_bound_count;
 
-       return count == 0;
-}
-
-static ast_t
-processor_csw_check(processor_t processor)
-{
-       run_queue_t             runq;
-
-       assert(processor->active_thread != NULL);
-       
-       runq = runq_for_processor(processor);
-       if (runq->highq > processor->current_pri) {
-               if (runq->urgency > 0)
-                       return (AST_PREEMPT | AST_URGENT);
-               
-               if (processor->active_thread && thread_eager_preemption(processor->active_thread))
-                       return (AST_PREEMPT | AST_URGENT);
-
-               return AST_PREEMPT;
+       if (do_signal_idle == eDoSignal) {
+               machine_signal_idle(processor);
+       }
+#if defined(CONFIG_SCHED_DEFERRED_AST)
+       else if (do_signal_idle == eDoDeferredSignal) {
+               /*
+                * TODO: The ability to cancel this signal could make
+                * sending it outside of the pset lock an issue.  Do
+                * we need to address this?  Or would the only fallout
+                * be that the core takes a signal?  As long as we do
+                * not run the risk of having a core marked as signal
+                * outstanding, with no real signal outstanding, the
+                * only result should be that we fail to cancel some
+                * signals.
+                */
+               machine_signal_idle_deferred(processor);
+       }
+#endif
+       else if (do_cause_ast) {
+               cause_ast_check(processor);
        }
-
-       return AST_NONE;
-}
-
-static boolean_t
-processor_queue_has_priority(processor_t               processor,
-                                                        int                            priority,
-                                                        boolean_t                      gte)
-{
-       if (gte)
-               return runq_for_processor(processor)->highq >= priority;
-       else
-               return runq_for_processor(processor)->highq > priority;
-}
-
-static boolean_t
-should_current_thread_rechoose_processor(processor_t                   processor)
-{
-       return (processor->current_pri < BASEPRI_RTQUEUES
-                       && processor->processor_meta != PROCESSOR_META_NULL
-                       && processor->processor_meta->primary != processor);
-}
-
-static int
-sched_traditional_processor_runq_count(processor_t   processor)
-{
-       return runq_for_processor(processor)->count;
-}
-
-
-static uint64_t
-sched_traditional_processor_runq_stats_count_sum(processor_t   processor)
-{
-       return runq_for_processor(processor)->runq_stats.count_sum;
-}
-
-static uint64_t
-sched_traditional_with_pset_runqueue_processor_runq_stats_count_sum(processor_t   processor)
-{
-       if (processor->cpu_id == processor->processor_set->cpu_set_low)
-               return runq_for_processor(processor)->runq_stats.count_sum;
-       else
-               return 0ULL;
 }
 
-#endif /* CONFIG_SCHED_TRADITIONAL */
-
-#define next_pset(p)   (((p)->pset_list != PROCESSOR_SET_NULL)? (p)->pset_list: (p)->node->psets)
-
 /*
  *     choose_next_pset:
  *
@@ -3124,147 +3407,231 @@ choose_processor(
        thread_t                        thread)
 {
        processor_set_t         nset, cset = pset;
-       processor_meta_t        pmeta = PROCESSOR_META_NULL;
-       processor_t             mprocessor;
        
        /*
-        *      Prefer the hinted processor, when appropriate.
+        * Prefer the hinted processor, when appropriate.
         */
 
+       /* Fold last processor hint from secondary processor to its primary */
        if (processor != PROCESSOR_NULL) {
-               if (processor->processor_meta != PROCESSOR_META_NULL)
-                       processor = processor->processor_meta->primary;
+               processor = processor->processor_primary;
        }
 
-       mprocessor = machine_choose_processor(pset, processor);
-       if (mprocessor != PROCESSOR_NULL)
-               processor = mprocessor;
+       /*
+        * Only consult platform layer if pset is active, which
+        * it may not be in some cases when a multi-set system
+        * is going to sleep.
+        */
+       if (pset->online_processor_count) {
+               if ((processor == PROCESSOR_NULL) || (processor->processor_set == pset && processor->state == PROCESSOR_IDLE)) {
+                       processor_t mc_processor = machine_choose_processor(pset, processor);
+                       if (mc_processor != PROCESSOR_NULL)
+                               processor = mc_processor->processor_primary;
+               }
+       }
 
+       /*
+        * At this point, we may have a processor hint, and we may have
+        * an initial starting pset. If the hint is not in the pset, or
+        * if the hint is for a processor in an invalid state, discard
+        * the hint.
+        */
        if (processor != PROCESSOR_NULL) {
-               if (processor->processor_set != pset ||
-                   processor->state == PROCESSOR_INACTIVE ||
-                   processor->state == PROCESSOR_SHUTDOWN ||
-                   processor->state == PROCESSOR_OFF_LINE)
+               if (processor->processor_set != pset) {
                        processor = PROCESSOR_NULL;
-               else
-                       if (processor->state == PROCESSOR_IDLE ||
-                           ((thread->sched_pri >= BASEPRI_RTQUEUES) &&
-                           (processor->current_pri < BASEPRI_RTQUEUES)))
-                               return (processor);
+               } else if (!processor->is_recommended) {
+                       processor = PROCESSOR_NULL;
+               } else {
+                       switch (processor->state) {
+                               case PROCESSOR_START:
+                               case PROCESSOR_SHUTDOWN:
+                               case PROCESSOR_OFF_LINE:
+                                       /*
+                                        * Hint is for a processor that cannot support running new threads.
+                                        */
+                                       processor = PROCESSOR_NULL;
+                                       break;
+                               case PROCESSOR_IDLE:
+                                       /*
+                                        * Hint is for an idle processor. Assume it is no worse than any other
+                                        * idle processor. The platform layer had an opportunity to provide
+                                        * the "least cost idle" processor above.
+                                        */
+                                       return (processor);
+                                       break;
+                               case PROCESSOR_RUNNING:
+                               case PROCESSOR_DISPATCHING:
+                                       /*
+                                        * Hint is for an active CPU. This fast-path allows
+                                        * realtime threads to preempt non-realtime threads
+                                        * to regain their previous executing processor.
+                                        */
+                                       if ((thread->sched_pri >= BASEPRI_RTQUEUES) &&
+                                               (processor->current_pri < BASEPRI_RTQUEUES))
+                                               return (processor);
+
+                                       /* Otherwise, use hint as part of search below */
+                                       break;
+                               default:
+                                       processor = PROCESSOR_NULL;
+                                       break;
+                       }
+               }
        }
 
        /*
-        *      Iterate through the processor sets to locate
-        *      an appropriate processor.
+        * Iterate through the processor sets to locate
+        * an appropriate processor. Seed results with
+        * a last-processor hint, if available, so that
+        * a search must find something strictly better
+        * to replace it.
+        *
+        * A primary/secondary pair of SMT processors are
+        * "unpaired" if the primary is busy but its
+        * corresponding secondary is idle (so the physical
+        * core has full use of its resources).
         */
+
+       integer_t lowest_priority = MAXPRI + 1;
+       integer_t lowest_unpaired_primary_priority = MAXPRI + 1;
+       integer_t lowest_count = INT_MAX;
+       uint64_t  furthest_deadline = 1;
+       processor_t lp_processor = PROCESSOR_NULL;
+       processor_t lp_unpaired_primary_processor = PROCESSOR_NULL;
+       processor_t lp_unpaired_secondary_processor = PROCESSOR_NULL;
+       processor_t lc_processor = PROCESSOR_NULL;
+       processor_t fd_processor = PROCESSOR_NULL;
+
+       if (processor != PROCESSOR_NULL) {
+               /* All other states should be enumerated above. */
+               assert(processor->state == PROCESSOR_RUNNING || processor->state == PROCESSOR_DISPATCHING);
+
+               lowest_priority = processor->current_pri;
+               lp_processor = processor;
+
+               if (processor->current_pri >= BASEPRI_RTQUEUES) {
+                       furthest_deadline = processor->deadline;
+                       fd_processor = processor;
+               }
+
+               lowest_count = SCHED(processor_runq_count)(processor);
+               lc_processor = processor;
+       }
+
        do {
+
                /*
-                *      Choose an idle processor.
+                * Choose an idle processor, in pset traversal order
                 */
-               if (!queue_empty(&cset->idle_queue))
-                       return ((processor_t)queue_first(&cset->idle_queue));
+               qe_foreach_element(processor, &cset->idle_queue, processor_queue) {
+                       if (processor->is_recommended)
+                               return processor;
+               }
 
-               if (thread->sched_pri >= BASEPRI_RTQUEUES) {
-                       integer_t lowest_priority = MAXPRI + 1;
-                       integer_t lowest_unpaired = MAXPRI + 1;
-                       uint64_t  furthest_deadline = 1;
-                       processor_t lp_processor = PROCESSOR_NULL;
-                       processor_t lp_unpaired = PROCESSOR_NULL;
-                       processor_t fd_processor = PROCESSOR_NULL;
-
-                       lp_processor = cset->low_pri;
-                       /* Consider hinted processor */
-                       if (lp_processor != PROCESSOR_NULL &&
-                           ((lp_processor->processor_meta == PROCESSOR_META_NULL) ||
-                           ((lp_processor == lp_processor->processor_meta->primary) &&
-                           !queue_empty(&lp_processor->processor_meta->idle_queue))) &&
-                           lp_processor->state != PROCESSOR_INACTIVE &&
-                           lp_processor->state != PROCESSOR_SHUTDOWN &&
-                           lp_processor->state != PROCESSOR_OFF_LINE &&
-                           (lp_processor->current_pri < thread->sched_pri))
-                               return lp_processor;
+               /*
+                * Otherwise, enumerate active and idle processors to find candidates
+                * with lower priority/etc.
+                */
 
-                       processor = (processor_t)queue_first(&cset->active_queue);
-                       while (!queue_end(&cset->active_queue, (queue_entry_t)processor)) {
-                               /* Discover the processor executing the
-                                * thread with the lowest priority within
-                                * this pset, or the one with the furthest
-                                * deadline
-                                */
-                               integer_t cpri = processor->current_pri;
-                               if (cpri < lowest_priority) {
-                                       lowest_priority = cpri;
-                                       lp_processor = processor;
-                               }
+               qe_foreach_element(processor, &cset->active_queue, processor_queue) {
 
-                               if ((cpri >= BASEPRI_RTQUEUES) && (processor->deadline > furthest_deadline)) {
-                                       furthest_deadline = processor->deadline;
-                                       fd_processor = processor;
-                               }
+                       if (!processor->is_recommended) {
+                               continue;
+                       }
 
+                       integer_t cpri = processor->current_pri;
+                       if (cpri < lowest_priority) {
+                               lowest_priority = cpri;
+                               lp_processor = processor;
+                       }
 
-                               if (processor->processor_meta != PROCESSOR_META_NULL &&
-                                   !queue_empty(&processor->processor_meta->idle_queue)) {
-                                       if (cpri < lowest_unpaired) {
-                                               lowest_unpaired = cpri;
-                                               lp_unpaired = processor;
-                                               pmeta = processor->processor_meta;
-                                       }
-                                       else
-                                               if (pmeta == PROCESSOR_META_NULL)
-                                                       pmeta = processor->processor_meta;
+                       if ((cpri >= BASEPRI_RTQUEUES) && (processor->deadline > furthest_deadline)) {
+                               furthest_deadline = processor->deadline;
+                               fd_processor = processor;
+                       }
+
+                       integer_t ccount = SCHED(processor_runq_count)(processor);
+                       if (ccount < lowest_count) {
+                               lowest_count = ccount;
+                               lc_processor = processor;
+                       }
+               }
+
+               /*
+                * For SMT configs, these idle secondary processors must have active primary. Otherwise
+                * the idle primary would have short-circuited the loop above
+                */
+               qe_foreach_element(processor, &cset->idle_secondary_queue, processor_queue) {
+
+                       if (!processor->is_recommended) {
+                               continue;
+                       }
+
+                       processor_t cprimary = processor->processor_primary;
+
+                       /* If the primary processor is offline or starting up, it's not a candidate for this path */
+                       if (cprimary->state == PROCESSOR_RUNNING || cprimary->state == PROCESSOR_DISPATCHING) {
+                               integer_t primary_pri = cprimary->current_pri;
+
+                               if (primary_pri < lowest_unpaired_primary_priority) {
+                                       lowest_unpaired_primary_priority = primary_pri;
+                                       lp_unpaired_primary_processor = cprimary;
+                                       lp_unpaired_secondary_processor = processor;
                                }
-                               processor = (processor_t)queue_next((queue_entry_t)processor);
                        }
+               }
+
 
-                       if (thread->sched_pri > lowest_unpaired)
-                               return lp_unpaired;
+               if (thread->sched_pri >= BASEPRI_RTQUEUES) {
+
+                       /*
+                        * For realtime threads, the most important aspect is
+                        * scheduling latency, so we attempt to assign threads
+                        * to good preemption candidates (assuming an idle primary
+                        * processor was not available above).
+                        */
 
-                       if (pmeta != PROCESSOR_META_NULL)
-                               return ((processor_t)queue_first(&pmeta->idle_queue));
-                       if (thread->sched_pri > lowest_priority)
+                       if (thread->sched_pri > lowest_unpaired_primary_priority) {
+                               /* Move to end of active queue so that the next thread doesn't also pick it */
+                               re_queue_tail(&cset->active_queue, (queue_entry_t)lp_unpaired_primary_processor);
+                               return lp_unpaired_primary_processor;
+                       }
+                       if (thread->sched_pri > lowest_priority) {
+                               /* Move to end of active queue so that the next thread doesn't also pick it */
+                               re_queue_tail(&cset->active_queue, (queue_entry_t)lp_processor);
                                return lp_processor;
+                       }
                        if (thread->realtime.deadline < furthest_deadline)
                                return fd_processor;
 
-                       processor = PROCESSOR_NULL;
-               }
-               else {
                        /*
-                        *      Check any hinted processors in the processor set if available.
+                        * If all primary and secondary CPUs are busy with realtime
+                        * threads with deadlines earlier than us, move on to next
+                        * pset.
                         */
-                       if (cset->low_pri != PROCESSOR_NULL && cset->low_pri->state != PROCESSOR_INACTIVE &&
-                                       cset->low_pri->state != PROCESSOR_SHUTDOWN && cset->low_pri->state != PROCESSOR_OFF_LINE &&
-                                               (processor == PROCESSOR_NULL ||
-                                                       (thread->sched_pri > BASEPRI_DEFAULT && cset->low_pri->current_pri < thread->sched_pri))) {
-                               processor = cset->low_pri;
+               }
+               else {
+
+                       if (thread->sched_pri > lowest_unpaired_primary_priority) {
+                               /* Move to end of active queue so that the next thread doesn't also pick it */
+                               re_queue_tail(&cset->active_queue, (queue_entry_t)lp_unpaired_primary_processor);
+                               return lp_unpaired_primary_processor;
                        }
-                       else
-                       if (cset->low_count != PROCESSOR_NULL && cset->low_count->state != PROCESSOR_INACTIVE &&
-                                       cset->low_count->state != PROCESSOR_SHUTDOWN && cset->low_count->state != PROCESSOR_OFF_LINE &&
-                                               (processor == PROCESSOR_NULL || (thread->sched_pri <= BASEPRI_DEFAULT &&
-                                                                                                                       SCHED(processor_runq_count)(cset->low_count) < SCHED(processor_runq_count)(processor)))) {
-                               processor = cset->low_count;
+                       if (thread->sched_pri > lowest_priority) {
+                               /* Move to end of active queue so that the next thread doesn't also pick it */
+                               re_queue_tail(&cset->active_queue, (queue_entry_t)lp_processor);
+                               return lp_processor;
                        }
 
                        /*
-                        *      Otherwise, choose an available processor in the set.
+                        * If all primary processor in this pset are running a higher
+                        * priority thread, move on to next pset. Only when we have
+                        * exhausted this search do we fall back to other heuristics.
                         */
-                       if (processor == PROCESSOR_NULL) {
-                               processor = (processor_t)dequeue_head(&cset->active_queue);
-                               if (processor != PROCESSOR_NULL)
-                                       enqueue_tail(&cset->active_queue, (queue_entry_t)processor);
-                       }
-
-                       if (processor != PROCESSOR_NULL && pmeta == PROCESSOR_META_NULL) {
-                               if (processor->processor_meta != PROCESSOR_META_NULL &&
-                                                                                       !queue_empty(&processor->processor_meta->idle_queue))
-                                       pmeta = processor->processor_meta;
-                       }
                }
 
                /*
-                *      Move onto the next processor set.
+                * Move onto the next processor set.
                 */
                nset = next_pset(cset);
 
@@ -3277,62 +3644,54 @@ choose_processor(
        } while (nset != pset);
 
        /*
-        *      Make sure that we pick a running processor,
-        *      and that the correct processor set is locked.
+        * Make sure that we pick a running processor,
+        * and that the correct processor set is locked.
+        * Since we may have unlock the candidate processor's
+        * pset, it may have changed state.
+        *
+        * All primary processors are running a higher priority
+        * thread, so the only options left are enqueuing on
+        * the secondary processor that would perturb the least priority
+        * primary, or the least busy primary.
         */
        do {
-               if (pmeta != PROCESSOR_META_NULL) {
-                       if (cset != pmeta->primary->processor_set) {
-                               pset_unlock(cset);
-
-                               cset = pmeta->primary->processor_set;
-                               pset_lock(cset);
-                       }
-
-                       if (!queue_empty(&pmeta->idle_queue))
-                               return ((processor_t)queue_first(&pmeta->idle_queue));
-
-                       pmeta = PROCESSOR_META_NULL;
-               }
-
-               /*
-                *      If we haven't been able to choose a processor,
-                *      pick the boot processor and return it.
-                */
-               if (processor == PROCESSOR_NULL) {
-                       processor = master_processor;
 
+               /* lowest_priority is evaluated in the main loops above */
+               if (lp_unpaired_secondary_processor != PROCESSOR_NULL) {
+                       processor = lp_unpaired_secondary_processor;
+                       lp_unpaired_secondary_processor = PROCESSOR_NULL;
+               } else if (lc_processor != PROCESSOR_NULL) {
+                       processor = lc_processor;
+                       lc_processor = PROCESSOR_NULL;
+               } else {
                        /*
-                        *      Check that the correct processor set is
-                        *      returned locked.
+                        * All processors are executing higher
+                        * priority threads, and the lowest_count
+                        * candidate was not usable
                         */
-                       if (cset != processor->processor_set) {
-                               pset_unlock(cset);
-
-                               cset = processor->processor_set;
-                               pset_lock(cset);
-                       }
-
-                       return (processor);
+                       processor = master_processor;
                }
 
                /*
-                *      Check that the processor set for the chosen
-                *      processor is locked.
+                * Check that the correct processor set is
+                * returned locked.
                 */
                if (cset != processor->processor_set) {
                        pset_unlock(cset);
-
                        cset = processor->processor_set;
                        pset_lock(cset);
                }
 
                /*
-                *      We must verify that the chosen processor is still available.
+                * We must verify that the chosen processor is still available.
+                * master_processor is an exception, since we may need to preempt
+                * a running thread on it during processor shutdown (for sleep),
+                * and that thread needs to be enqueued on its runqueue to run
+                * when the processor is restarted.
                 */
-               if (processor->state == PROCESSOR_INACTIVE ||
-                                       processor->state == PROCESSOR_SHUTDOWN || processor->state == PROCESSOR_OFF_LINE)
+               if (processor != master_processor && (processor->state == PROCESSOR_SHUTDOWN || processor->state == PROCESSOR_OFF_LINE))
                        processor = PROCESSOR_NULL;
+
        } while (processor == PROCESSOR_NULL);
 
        return (processor);
@@ -3355,18 +3714,20 @@ thread_setrun(
        processor_t                     processor;
        processor_set_t         pset;
 
-#if DEBUG
-       assert(thread_runnable(thread));
-#endif
-       
+       assert((thread->state & (TH_RUN|TH_WAIT|TH_UNINT|TH_TERMINATE|TH_TERMINATE2)) == TH_RUN);
+       assert(thread->runq == PROCESSOR_NULL);
+
        /*
         *      Update priority if needed.
         */
        if (SCHED(can_update_priority)(thread))
                SCHED(update_priority)(thread);
 
+       thread->sfi_class = sfi_thread_classify(thread);
+
        assert(thread->runq == PROCESSOR_NULL);
 
+#if __SMP__
        if (thread->bound_processor == PROCESSOR_NULL) {
                /*
                 *      Unbound case.
@@ -3379,9 +3740,10 @@ thread_setrun(
                        pset_lock(pset);
 
                        processor = SCHED(choose_processor)(pset, PROCESSOR_NULL, thread);
-               }
-               else
-               if (thread->last_processor != PROCESSOR_NULL) {
+
+                       SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHOOSE_PROCESSOR)|DBG_FUNC_NONE,
+                                                                         (uintptr_t)thread_tid(thread), (uintptr_t)-1, processor->cpu_id, processor->state, 0);
+               } else if (thread->last_processor != PROCESSOR_NULL) {
                        /*
                         *      Simple (last processor) affinity case.
                         */
@@ -3390,13 +3752,9 @@ thread_setrun(
                        pset_lock(pset);
                        processor = SCHED(choose_processor)(pset, processor, thread);
 
-                       if ((thread->last_processor != processor) && (thread->last_processor != PROCESSOR_NULL)) {
-                               KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_LPA_BROKEN)|DBG_FUNC_NONE,
-                                                                         (uintptr_t)thread_tid(thread), (uintptr_t)thread->last_processor->cpu_id, (uintptr_t)processor->cpu_id, thread->last_processor->state, 0);
-                       }
-                       
-               }
-               else {
+                       SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHOOSE_PROCESSOR)|DBG_FUNC_NONE,
+                                                                 (uintptr_t)thread_tid(thread), thread->last_processor->cpu_id, processor->cpu_id, processor->state, 0);
+               } else {
                        /*
                         *      No Affinity case:
                         *
@@ -3414,9 +3772,11 @@ thread_setrun(
 
                        processor = SCHED(choose_processor)(pset, PROCESSOR_NULL, thread);
                        task->pset_hint = processor->processor_set;
+
+                       SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHOOSE_PROCESSOR)|DBG_FUNC_NONE,
+                                                                         (uintptr_t)thread_tid(thread), (uintptr_t)-1, processor->cpu_id, processor->state, 0);
                }
-       }
-       else {
+       } else {
                /*
                 *      Bound case:
                 *
@@ -3425,15 +3785,24 @@ thread_setrun(
                processor = thread->bound_processor;
                pset = processor->processor_set;
                pset_lock(pset);
+
+               SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHOOSE_PROCESSOR)|DBG_FUNC_NONE,
+                                                         (uintptr_t)thread_tid(thread), (uintptr_t)-2, processor->cpu_id, processor->state, 0);
        }
+#else /* !__SMP__ */
+       /* Only one processor to choose */
+       assert(thread->bound_processor == PROCESSOR_NULL || thread->bound_processor == master_processor);
+       processor = master_processor;
+       pset = processor->processor_set;
+       pset_lock(pset);
+#endif /* !__SMP__ */
 
        /*
-        *      Dispatch the thread on the choosen processor.
+        *      Dispatch the thread on the chosen processor.
+        *      TODO: This should be based on sched_mode, not sched_pri
         */
        if (thread->sched_pri >= BASEPRI_RTQUEUES)
                realtime_setrun(processor, thread);
-       else if (thread->sched_mode == TH_MODE_FAIRSHARE)
-               fairshare_setrun(processor, thread);
        else
                processor_setrun(processor, thread, options);
 }
@@ -3450,114 +3819,103 @@ task_choose_pset(
        return (pset);
 }
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
-
 /*
- *     processor_queue_shutdown:
- *
- *     Shutdown a processor run queue by
- *     re-dispatching non-bound threads.
+ *     Check for a preemption point in
+ *     the current context.
  *
- *     Associated pset must be locked, and is
- *     returned unlocked.
+ *     Called at splsched with thread locked.
  */
-void
-processor_queue_shutdown(
-       processor_t                     processor)
+ast_t
+csw_check(
+       processor_t             processor,
+       ast_t                   check_reason)
 {
-       processor_set_t         pset = processor->processor_set;
-       run_queue_t                     rq = runq_for_processor(processor);
-       queue_t                         queue = rq->queues + rq->highq;
-       int                                     pri = rq->highq, count = rq->count;
-       thread_t                        next, thread;
-       queue_head_t            tqueue;
+       processor_set_t pset = processor->processor_set;
+       ast_t                   result;
 
-       queue_init(&tqueue);
-       
-       while (count > 0) {
-               thread = (thread_t)queue_first(queue);
-               while (!queue_end(queue, (queue_entry_t)thread)) {
-                       next = (thread_t)queue_next((queue_entry_t)thread);
-
-                       if (thread->bound_processor == PROCESSOR_NULL) {
-                               remqueue((queue_entry_t)thread);
-
-                               thread->runq = PROCESSOR_NULL;
-                               SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count);
-                               runq_consider_decr_bound_count(processor, thread);
-                               rq->count--;
-                               if (SCHED(priority_is_urgent)(pri)) {
-                                       rq->urgency--; assert(rq->urgency >= 0);
-                               }
-                               if (queue_empty(queue)) {
-                                       if (pri != IDLEPRI)
-                                               clrbit(MAXPRI - pri, rq->bitmap);
-                                       rq->highq = MAXPRI - ffsbit(rq->bitmap);
-                               }
-
-                               enqueue_tail(&tqueue, (queue_entry_t)thread);
-                       }
-                       count--;
+       pset_lock(pset);
 
-                       thread = next;
-               }
+       /* If we were sent a remote AST and interrupted a running processor, acknowledge it here with pset lock held */
+       pset->pending_AST_cpu_mask &= ~(1ULL << processor->cpu_id);
 
-               queue--; pri--;
-       }
+       result = csw_check_locked(processor, pset, check_reason);
 
        pset_unlock(pset);
 
-       while ((thread = (thread_t)dequeue_head(&tqueue)) != THREAD_NULL) {
-               thread_lock(thread);
-
-               thread_setrun(thread, SCHED_TAILQ);
-
-               thread_unlock(thread);
-       }
+       return result;
 }
 
-#endif /* CONFIG_SCHED_TRADITIONAL */
-
 /*
- *     Check for a preemption point in
- *     the current context.
- *
- *     Called at splsched.
+ * Check for preemption at splsched with
+ * pset and thread locked
  */
 ast_t
-csw_check(
-       processor_t             processor)
+csw_check_locked(
+       processor_t             processor,
+       processor_set_t pset __unused,
+       ast_t                   check_reason)
 {
-       ast_t                   result = AST_NONE;
+       ast_t                   result;
+       thread_t                thread = processor->active_thread;
 
-       if (first_timeslice(processor)) {
+       if (processor->first_timeslice) {
                if (rt_runq.count > 0)
-                       return (AST_PREEMPT | AST_URGENT);
-
-               result |= SCHED(processor_csw_check)(processor);
-               if (result & AST_URGENT)
-                       return result;
+                       return (check_reason | AST_PREEMPT | AST_URGENT);
        }
        else {
-               if (rt_runq.count > 0 && BASEPRI_RTQUEUES >= processor->current_pri)
-                       return (AST_PREEMPT | AST_URGENT);
-
-               result |= SCHED(processor_csw_check)(processor);
-               if (result & AST_URGENT)
-                       return result;
+               if (rt_runq.count > 0) {
+                       if (BASEPRI_RTQUEUES > processor->current_pri)
+                               return (check_reason | AST_PREEMPT | AST_URGENT);
+                       else
+                               return (check_reason | AST_PREEMPT);
+               }
        }
 
+       result = SCHED(processor_csw_check)(processor);
        if (result != AST_NONE)
-               return (result);
+               return (check_reason | result | (thread_eager_preemption(thread) ? AST_URGENT : AST_NONE));
 
-       if (SCHED(should_current_thread_rechoose_processor)(processor))
-               return (AST_PREEMPT);
-       
-       if (machine_processor_is_inactive(processor))
-               return (AST_PREEMPT);
+#if __SMP__
+
+       /*
+        * If the current thread is running on a processor that is no longer recommended, gently
+        * (non-urgently) get to a point and then block, and which point thread_select() should
+        * try to idle the processor and re-dispatch the thread to a recommended processor.
+        */
+       if (!processor->is_recommended)
+               return (check_reason | AST_PREEMPT);
+
+       /*
+        * Even though we could continue executing on this processor, a
+        * secondary SMT core should try to shed load to another primary core.
+        *
+        * TODO: Should this do the same check that thread_select does? i.e.
+        * if no bound threads target this processor, and idle primaries exist, preempt
+        * The case of RT threads existing is already taken care of above
+        * Consider Capri in this scenario.
+        *
+        * if (!SCHED(processor_bound_count)(processor) && !queue_empty(&pset->idle_queue))
+        *
+        * TODO: Alternatively - check if only primary is idle, or check if primary's pri is lower than mine.
+        */
+
+       if (processor->current_pri < BASEPRI_RTQUEUES &&
+           processor->processor_primary != processor)
+               return (check_reason | AST_PREEMPT);
+#endif
 
-       if (processor->active_thread->state & TH_SUSP)
-               return (AST_PREEMPT);
+       if (thread->state & TH_SUSP)
+               return (check_reason | AST_PREEMPT);
+
+#if CONFIG_SCHED_SFI
+       /*
+        * Current thread may not need to be preempted, but maybe needs
+        * an SFI wait?
+        */
+       result = sfi_thread_needs_ast(thread, NULL);
+       if (result != AST_NONE)
+               return (check_reason | result);
+#endif
 
        return (AST_NONE);
 }
@@ -3573,317 +3931,239 @@ csw_check(
  */
 void
 set_sched_pri(
-       thread_t                thread,
-       int                             priority)
+              thread_t        thread,
+              int             priority)
 {
-       boolean_t               removed = thread_run_queue_remove(thread);
-
-       thread->sched_pri = priority;
-       if (removed)
-               thread_setrun(thread, SCHED_PREEMPT | SCHED_TAILQ);
-       else
-       if (thread->state & TH_RUN) {
-               processor_t             processor = thread->last_processor;
-
-               if (thread == current_thread()) {
-                       ast_t                   preempt;
+       thread_t cthread = current_thread();
+       boolean_t is_current_thread = (thread == cthread) ? TRUE : FALSE;
+       int curgency, nurgency;
+       uint64_t urgency_param1, urgency_param2;
+       boolean_t removed_from_runq = FALSE;
+
+       /* If we're already at this priority, no need to mess with the runqueue */
+       if (priority == thread->sched_pri)
+               return;
 
-                       processor->current_pri = priority;
-                       processor->current_thmode = thread->sched_mode;
-                       if ((preempt = csw_check(processor)) != AST_NONE)
-                               ast_on(preempt);
-               }
-               else
-               if (    processor != PROCESSOR_NULL                                             &&
-                               processor->active_thread == thread      )
-                       cause_ast_check(processor);
+       if (is_current_thread) {
+               assert(thread->runq == PROCESSOR_NULL);
+               curgency = thread_get_urgency(thread, &urgency_param1, &urgency_param2);
+       } else {
+               removed_from_runq = thread_run_queue_remove(thread);
        }
-}
 
-#if            0
+       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHANGE_PRIORITY),
+                             (uintptr_t)thread_tid(thread),
+                             thread->base_pri,
+                             thread->sched_pri,
+                             0, /* eventually, 'reason' */
+                             0);
 
-static void
-run_queue_check(
-       run_queue_t             rq,
-       thread_t                thread)
-{
-       queue_t                 q;
-       queue_entry_t   qe;
+       thread->sched_pri = priority;
 
-       if (rq != thread->runq)
-               panic("run_queue_check: thread runq");
+       if (is_current_thread) {
+               nurgency = thread_get_urgency(thread, &urgency_param1, &urgency_param2);
+               /*
+                * set_sched_pri doesn't alter RT params. We expect direct base priority/QoS
+                * class alterations from user space to occur relatively infrequently, hence
+                * those are lazily handled. QoS classes have distinct priority bands, and QoS
+                * inheritance is expected to involve priority changes.
+                */
+               if (nurgency != curgency) {
+                       thread_tell_urgency(nurgency, urgency_param1, urgency_param2, 0, thread);
+                       machine_thread_going_on_core(thread, nurgency, 0);
+               }
+       }
 
-       if (thread->sched_pri > MAXPRI || thread->sched_pri < MINPRI)
-               panic("run_queue_check: thread sched_pri");
+       /* TODO: Should this be TAILQ if it went down, HEADQ if it went up? */
+       if (removed_from_runq)
+               thread_run_queue_reinsert(thread, SCHED_PREEMPT | SCHED_TAILQ);
+       else if (thread->state & TH_RUN) {
+               processor_t processor = thread->last_processor;
 
-       q = &rq->queues[thread->sched_pri];
-       qe = queue_first(q);
-       while (!queue_end(q, qe)) {
-               if (qe == (queue_entry_t)thread)
-                       return;
+               if (is_current_thread) {
+                       ast_t preempt;
 
-               qe = queue_next(qe);
+                       processor->current_pri = priority;
+                       processor->current_thmode = thread->sched_mode;
+                       processor->current_sfi_class = thread->sfi_class = sfi_thread_classify(thread);
+                       if ((preempt = csw_check(processor, AST_NONE)) != AST_NONE)
+                               ast_on(preempt);
+               } else if (processor != PROCESSOR_NULL && processor->active_thread == thread)
+                       cause_ast_check(processor);
        }
-
-       panic("run_queue_check: end");
 }
 
-#endif /* DEBUG */
-
-#if defined(CONFIG_SCHED_TRADITIONAL)
-
-/* locks the runqueue itself */
+/*
+ * thread_run_queue_remove_for_handoff
+ *
+ * Pull a thread or its (recursive) push target out of the runqueue
+ * so that it is ready for thread_run()
+ *
+ * Called at splsched
+ *
+ * Returns the thread that was pulled or THREAD_NULL if no thread could be pulled.
+ * This may be different than the thread that was passed in.
+ */
+thread_t
+thread_run_queue_remove_for_handoff(thread_t thread) {
 
-static boolean_t
-processor_queue_remove(
-                                          processor_t                  processor,
-                                          thread_t             thread)
-{
-       void *                  rqlock;
-       run_queue_t             rq;
-       
-       rqlock = &processor->processor_set->sched_lock;
-       rq = runq_for_processor(processor);
+       thread_t pulled_thread = THREAD_NULL;
 
-       simple_lock(rqlock);
-       if (processor == thread->runq) {
-               /*
-                *      Thread is on a run queue and we have a lock on
-                *      that run queue.
-                */
-               runq_consider_decr_bound_count(processor, thread);
-               run_queue_remove(rq, thread);
-       }
-       else {
-               /*
-                *      The thread left the run queue before we could
-                *      lock the run queue.
-                */
-               assert(thread->runq == PROCESSOR_NULL);
-               processor = PROCESSOR_NULL;
+       thread_lock(thread);
+
+       /*
+        * Check that the thread is not bound
+        * to a different processor, and that realtime
+        * is not involved.
+        *
+        * Next, pull it off its run queue.  If it
+        * doesn't come, it's not eligible.
+        */
+
+       processor_t processor = current_processor();
+       if (processor->current_pri < BASEPRI_RTQUEUES && thread->sched_pri < BASEPRI_RTQUEUES &&
+           (thread->bound_processor == PROCESSOR_NULL || thread->bound_processor == processor)) {
+
+                       if (thread_run_queue_remove(thread))
+                               pulled_thread = thread;
        }
-       
-       simple_unlock(rqlock);
 
-       return (processor != PROCESSOR_NULL);
-}
+       thread_unlock(thread);
 
-#endif /* CONFIG_SCHED_TRADITIONAL */
+       return pulled_thread;
+}
 
 /*
  *     thread_run_queue_remove:
  *
- *     Remove a thread from a current run queue and
+ *     Remove a thread from its current run queue and
  *     return TRUE if successful.
  *
  *     Thread must be locked.
+ *
+ *     If thread->runq is PROCESSOR_NULL, the thread will not re-enter the
+ *     run queues because the caller locked the thread.  Otherwise
+ *     the thread is on a run queue, but could be chosen for dispatch
+ *     and removed by another processor under a different lock, which
+ *     will set thread->runq to PROCESSOR_NULL.
+ *
+ *     Hence the thread select path must not rely on anything that could
+ *     be changed under the thread lock after calling this function,
+ *     most importantly thread->sched_pri.
  */
 boolean_t
 thread_run_queue_remove(
-       thread_t                thread)
+                        thread_t        thread)
 {
-       processor_t             processor = thread->runq;
+       boolean_t removed = FALSE;
+       processor_t processor = thread->runq;
 
-       /*
-        *      If processor is PROCESSOR_NULL, the thread will stay out of the
-        *      run queues because the caller locked the thread.  Otherwise
-        *      the thread is on a run queue, but could be chosen for dispatch
-        *      and removed.
-        */
-       if (processor != PROCESSOR_NULL) {
-               queue_t                 q;
+       if ((thread->state & (TH_RUN|TH_WAIT)) == TH_WAIT) {
+               /* Thread isn't runnable */
+               assert(thread->runq == PROCESSOR_NULL);
+               return FALSE;
+       }
 
+       if (processor == PROCESSOR_NULL) {
                /*
-                *      The processor run queues are locked by the
-                *      processor set.  Real-time priorities use a
-                *      global queue with a dedicated lock.
+                * The thread is either not on the runq,
+                * or is in the midst of being removed from the runq.
+                *
+                * runq is set to NULL under the pset lock, not the thread
+                * lock, so the thread may still be in the process of being dequeued
+                * from the runq. It will wait in invoke for the thread lock to be
+                * dropped.
                 */
-               if (thread->sched_mode == TH_MODE_FAIRSHARE) {
-                       return SCHED(fairshare_queue_remove)(thread);
-               }
-               
-               if (thread->sched_pri < BASEPRI_RTQUEUES) {
-                       return SCHED(processor_queue_remove)(processor, thread);
-               }
-
-               simple_lock(&rt_lock);
-               q = &rt_runq.queue;
-
-               if (processor == thread->runq) {
-                       /*
-                        *      Thread is on a run queue and we have a lock on
-                        *      that run queue.
-                        */
-                       remqueue((queue_entry_t)thread);
-                       SCHED_STATS_RUNQ_CHANGE(&rt_runq.runq_stats, rt_runq.count);
-                       rt_runq.count--;
-
-                       thread->runq = PROCESSOR_NULL;
-               }
-               else {
-                       /*
-                        *      The thread left the run queue before we could
-                        *      lock the run queue.
-                        */
-                       assert(thread->runq == PROCESSOR_NULL);
-                       processor = PROCESSOR_NULL;
-               }
 
-               simple_unlock(&rt_lock);
+               return FALSE;
        }
 
-       return (processor != PROCESSOR_NULL);
-}
+       if (thread->sched_pri < BASEPRI_RTQUEUES) {
+               return SCHED(processor_queue_remove)(processor, thread);
+       }
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
+       rt_lock_lock();
 
-/*
- *     steal_processor_thread:
- *
- *     Locate a thread to steal from the processor and
- *     return it.
- *
- *     Associated pset must be locked.  Returns THREAD_NULL
- *     on failure.
- */
-static thread_t
-steal_processor_thread(
-       processor_t             processor)
-{
-       run_queue_t             rq = runq_for_processor(processor);
-       queue_t                 queue = rq->queues + rq->highq;
-       int                             pri = rq->highq, count = rq->count;
-       thread_t                thread;
+       if (thread->runq != PROCESSOR_NULL) {
+               /*
+                *      Thread is on the RT run queue and we have a lock on
+                *      that run queue.
+                */
 
-       while (count > 0) {
-               thread = (thread_t)queue_first(queue);
-               while (!queue_end(queue, (queue_entry_t)thread)) {
-                       if (thread->bound_processor == PROCESSOR_NULL) {
-                               remqueue((queue_entry_t)thread);
-
-                               thread->runq = PROCESSOR_NULL;
-                               SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count);
-                               runq_consider_decr_bound_count(processor, thread);
-                               rq->count--;
-                               if (SCHED(priority_is_urgent)(pri)) {
-                                       rq->urgency--; assert(rq->urgency >= 0);
-                               }
-                               if (queue_empty(queue)) {
-                                       if (pri != IDLEPRI)
-                                               clrbit(MAXPRI - pri, rq->bitmap);
-                                       rq->highq = MAXPRI - ffsbit(rq->bitmap);
-                               }
+               assert(thread->runq == THREAD_ON_RT_RUNQ);
 
-                               return (thread);
-                       }
-                       count--;
+               remqueue((queue_entry_t)thread);
+               SCHED_STATS_RUNQ_CHANGE(&rt_runq.runq_stats, rt_runq.count);
+               rt_runq.count--;
 
-                       thread = (thread_t)queue_next((queue_entry_t)thread);
-               }
+               thread->runq = PROCESSOR_NULL;
 
-               queue--; pri--;
+               removed = TRUE;
        }
 
-       return (THREAD_NULL);
+       rt_lock_unlock();
+
+       return (removed);
 }
 
 /*
- *     Locate and steal a thread, beginning
- *     at the pset.
+ * Put the thread back where it goes after a thread_run_queue_remove
  *
- *     The pset must be locked, and is returned
- *     unlocked.
+ * Thread must have been removed under the same thread lock hold
  *
- *     Returns the stolen thread, or THREAD_NULL on
- *     failure.
+ * thread locked, at splsched
  */
-static thread_t
-steal_thread(
-       processor_set_t         pset)
+void
+thread_run_queue_reinsert(thread_t thread, integer_t options)
 {
-       processor_set_t         nset, cset = pset;
-       processor_t                     processor;
-       thread_t                        thread;
-
-       do {
-               processor = (processor_t)queue_first(&cset->active_queue);
-               while (!queue_end(&cset->active_queue, (queue_entry_t)processor)) {
-                       if (runq_for_processor(processor)->count > 0) {
-                               thread = steal_processor_thread(processor);
-                               if (thread != THREAD_NULL) {
-                                       remqueue((queue_entry_t)processor);
-                                       enqueue_tail(&cset->active_queue, (queue_entry_t)processor);
-
-                                       pset_unlock(cset);
-
-                                       return (thread);
-                               }
-                       }
-
-                       processor = (processor_t)queue_next((queue_entry_t)processor);
-               }
-
-               nset = next_pset(cset);
-
-               if (nset != pset) {
-                       pset_unlock(cset);
-
-                       cset = nset;
-                       pset_lock(cset);
-               }
-       } while (nset != pset);
+       assert(thread->runq == PROCESSOR_NULL);
 
-       pset_unlock(cset);
+               assert(thread->state & (TH_RUN));
+               thread_setrun(thread, options);
 
-       return (THREAD_NULL);
 }
 
-static thread_t        steal_thread_disabled(
-                                       processor_set_t         pset)
+void
+sys_override_cpu_throttle(int flag)
 {
-       pset_unlock(pset);
-
-       return (THREAD_NULL);
+       if (flag == CPU_THROTTLE_ENABLE)
+               cpu_throttle_enabled = 1;
+       if (flag == CPU_THROTTLE_DISABLE)
+               cpu_throttle_enabled = 0;
 }
 
-#endif /* CONFIG_SCHED_TRADITIONAL */
-
-
 int
-thread_get_urgency(uint64_t *rt_period, uint64_t *rt_deadline)
+thread_get_urgency(thread_t thread, uint64_t *arg1, uint64_t *arg2)
 {
-       processor_t     processor;
-       thread_t        thread;
-       
-       processor = current_processor();
-
-       thread = processor->next_thread;
-
-       if (thread != NULL) {
-               if (thread->sched_mode == TH_MODE_REALTIME) {
-
-                       if (rt_period != NULL)
-                               *rt_period = thread->realtime.period;
-                       if (rt_deadline != NULL)
-                               *rt_deadline = thread->realtime.deadline;
-
-                       KERNEL_DEBUG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_GET_URGENCY), THREAD_URGENCY_REAL_TIME, thread->realtime.period,
-                           (thread->realtime.deadline >> 32), thread->realtime.deadline, 0);
-
-                       return (THREAD_URGENCY_REAL_TIME);
-               } else if ((thread->sched_pri <= MAXPRI_THROTTLE) &&
-                   (thread->priority <= MAXPRI_THROTTLE)) {
-                       KERNEL_DEBUG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_GET_URGENCY), THREAD_URGENCY_BACKGROUND, thread->sched_pri, thread->priority, 0, 0);
-                       return (THREAD_URGENCY_BACKGROUND);
-               }
-               else 
-                       KERNEL_DEBUG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_GET_URGENCY), THREAD_URGENCY_NORMAL, 0, 0, 0, 0);
+       if (thread == NULL || (thread->state & TH_IDLE)) {
+               *arg1 = 0;
+               *arg2 = 0;
+
+               return (THREAD_URGENCY_NONE);
+       } else if (thread->sched_mode == TH_MODE_REALTIME) {
+               *arg1 = thread->realtime.period;
+               *arg2 = thread->realtime.deadline;
+
+               return (THREAD_URGENCY_REAL_TIME);
+       } else if (cpu_throttle_enabled &&
+                  ((thread->sched_pri <= MAXPRI_THROTTLE) && (thread->base_pri <= MAXPRI_THROTTLE)))  {
+               /*
+                * Background urgency applied when thread priority is MAXPRI_THROTTLE or lower and thread is not promoted
+                * TODO: Use TH_SFLAG_THROTTLED instead?
+                */
+               *arg1 = thread->sched_pri;
+               *arg2 = thread->base_pri;
 
+               return (THREAD_URGENCY_BACKGROUND);
+       } else {
+               /* For otherwise unclassified threads, report throughput QoS
+                * parameters
+                */
+               *arg1 = thread->effective_policy.t_through_qos;
+               *arg2 = thread->task->effective_policy.t_through_qos;
+               
                return (THREAD_URGENCY_NORMAL);
        }
-       else
-               KERNEL_DEBUG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_GET_URGENCY), THREAD_URGENCY_NONE, 0, 0, 0, 0);
-       return (THREAD_URGENCY_NONE);
 }
 
 
@@ -3911,8 +4191,9 @@ processor_idle(
        int                                     state;
        (void)splsched();
 
-       KERNEL_DEBUG_CONSTANT(
-               MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_START, (uintptr_t)thread_tid(thread), 0, 0, 0, 0);
+       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+               MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_START, 
+               (uintptr_t)thread_tid(thread), 0, 0, 0, 0);
 
        SCHED_STATS_CPU_IDLE_START(processor);
 
@@ -3920,20 +4201,48 @@ processor_idle(
                                                                        mach_absolute_time(), &PROCESSOR_DATA(processor, idle_state));
        PROCESSOR_DATA(processor, current_state) = &PROCESSOR_DATA(processor, idle_state);
 
-       while (processor->next_thread == THREAD_NULL && SCHED(processor_queue_empty)(processor) && rt_runq.count == 0 && SCHED(fairshare_runq_count)() == 0 &&
-                               (thread == THREAD_NULL || ((thread->state & (TH_WAIT|TH_SUSP)) == TH_WAIT && !thread->wake_active))) {
+       while (1) {
+               if (processor->state != PROCESSOR_IDLE) /* unsafe, but worst case we loop around once */
+                       break;
+               if (pset->pending_AST_cpu_mask & (1ULL << processor->cpu_id))
+                       break;
+               if (processor->is_recommended) {
+                       if (rt_runq.count)
+                               break;
+               } else {
+                       if (SCHED(processor_bound_count)(processor))
+                               break;
+               }
+
+#if CONFIG_SCHED_IDLE_IN_PLACE
+               if (thread != THREAD_NULL) {
+                       /* Did idle-in-place thread wake up */
+                       if ((thread->state & (TH_WAIT|TH_SUSP)) != TH_WAIT || thread->wake_active)
+                               break;
+               }
+#endif
+
                IDLE_KERNEL_DEBUG_CONSTANT(
                        MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_NONE, (uintptr_t)thread_tid(thread), rt_runq.count, SCHED(processor_runq_count)(processor), -1, 0);
 
+               machine_track_platform_idle(TRUE);
+
                machine_idle();
 
+               machine_track_platform_idle(FALSE);
+
                (void)splsched();
 
                IDLE_KERNEL_DEBUG_CONSTANT(
                        MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_NONE, (uintptr_t)thread_tid(thread), rt_runq.count, SCHED(processor_runq_count)(processor), -2, 0);
 
-               if (processor->state == PROCESSOR_INACTIVE && !machine_processor_is_inactive(processor))
-                       break;
+               if (!SCHED(processor_queue_empty)(processor)) {
+                       /* Secondary SMT processors respond to directed wakeups
+                        * exclusively. Some platforms induce 'spurious' SMT wakeups.
+                        */
+                       if (processor->processor_primary == processor)
+                                       break;
+               }
        }
 
        timer_switch(&PROCESSOR_DATA(processor, idle_state),
@@ -3942,6 +4251,12 @@ processor_idle(
 
        pset_lock(pset);
 
+       /* If we were sent a remote AST and came out of idle, acknowledge it here with pset lock held */
+       pset->pending_AST_cpu_mask &= ~(1ULL << processor->cpu_id);
+#if defined(CONFIG_SCHED_DEFERRED_AST)
+       pset->pending_deferred_AST_cpu_mask &= ~(1ULL << processor->cpu_id);
+#endif
+
        state = processor->state;
        if (state == PROCESSOR_DISPATCHING) {
                /*
@@ -3951,8 +4266,12 @@ processor_idle(
                processor->next_thread = THREAD_NULL;
                processor->state = PROCESSOR_RUNNING;
 
-               if (SCHED(processor_queue_has_priority)(processor, new_thread->sched_pri, FALSE)                                        ||
-                               (rt_runq.count > 0 && BASEPRI_RTQUEUES >= new_thread->sched_pri)        ) {
+               if ((new_thread != THREAD_NULL) && (SCHED(processor_queue_has_priority)(processor, new_thread->sched_pri, FALSE)                                        ||
+                                                                                       (rt_runq.count > 0))    ) {
+                       /* Something higher priority has popped up on the runqueue - redispatch this thread elsewhere */
+                       processor->current_pri = IDLEPRI;
+                       processor->current_thmode = TH_MODE_FIXED;
+                       processor->current_sfi_class = SFI_CLASS_KERNEL;
                        processor->deadline = UINT64_MAX;
 
                        pset_unlock(pset);
@@ -3962,16 +4281,18 @@ processor_idle(
                        thread_setrun(new_thread, SCHED_HEADQ);
                        thread_unlock(new_thread);
 
-                       KERNEL_DEBUG_CONSTANT(
-                               MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_END, (uintptr_t)thread_tid(thread), state, 0, 0, 0);
+                       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                               MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_END, 
+                               (uintptr_t)thread_tid(thread), state, 0, 0, 0);
 
                        return (THREAD_NULL);
                }
 
                pset_unlock(pset);
 
-               KERNEL_DEBUG_CONSTANT(
-                                     MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_END, (uintptr_t)thread_tid(thread), state, (uintptr_t)thread_tid(new_thread), 0, 0);
+               KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                       MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_END, 
+                       (uintptr_t)thread_tid(thread), state, (uintptr_t)thread_tid(new_thread), 0, 0);
                        
                return (new_thread);
        }
@@ -3980,11 +4301,10 @@ processor_idle(
                remqueue((queue_entry_t)processor);
 
                processor->state = PROCESSOR_RUNNING;
-               enqueue_tail(&pset->active_queue, (queue_entry_t)processor);
-       }
-       else
-       if (state == PROCESSOR_INACTIVE) {
-               processor->state = PROCESSOR_RUNNING;
+               processor->current_pri = IDLEPRI;
+               processor->current_thmode = TH_MODE_FIXED;
+               processor->current_sfi_class = SFI_CLASS_KERNEL;
+               processor->deadline = UINT64_MAX;
                enqueue_tail(&pset->active_queue, (queue_entry_t)processor);
        }
        else
@@ -3995,6 +4315,9 @@ processor_idle(
                 */
                if ((new_thread = processor->next_thread) != THREAD_NULL) {
                        processor->next_thread = THREAD_NULL;
+                       processor->current_pri = IDLEPRI;
+                       processor->current_thmode = TH_MODE_FIXED;
+                       processor->current_sfi_class = SFI_CLASS_KERNEL;
                        processor->deadline = UINT64_MAX;
 
                        pset_unlock(pset);
@@ -4003,8 +4326,9 @@ processor_idle(
                        thread_setrun(new_thread, SCHED_HEADQ);
                        thread_unlock(new_thread);
 
-                       KERNEL_DEBUG_CONSTANT(
-                               MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_END, (uintptr_t)thread_tid(thread), state, 0, 0, 0);
+                       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+                               MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_END, 
+                               (uintptr_t)thread_tid(thread), state, 0, 0, 0);
                
                        return (THREAD_NULL);
                }
@@ -4012,8 +4336,9 @@ processor_idle(
 
        pset_unlock(pset);
 
-       KERNEL_DEBUG_CONSTANT(
-               MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_END, (uintptr_t)thread_tid(thread), state, 0, 0, 0);
+       KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
+               MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_END, 
+               (uintptr_t)thread_tid(thread), state, 0, 0, 0);
                
        return (THREAD_NULL);
 }
@@ -4055,8 +4380,9 @@ idle_thread_create(
        thread_lock(thread);
        thread->bound_processor = processor;
        processor->idle_thread = thread;
-       thread->sched_pri = thread->priority = IDLEPRI;
+       thread->sched_pri = thread->base_pri = IDLEPRI;
        thread->state = (TH_RUN | TH_IDLE);
+       thread->options |= TH_OPT_IDLE_THREAD;
        thread_unlock(thread);
        splx(s);
 
@@ -4078,135 +4404,193 @@ sched_startup(void)
        kern_return_t   result;
        thread_t                thread;
 
+       simple_lock_init(&sched_vm_group_list_lock, 0);
+
        result = kernel_thread_start_priority((thread_continue_t)sched_init_thread,
-                                                                                 (void *)SCHED(maintenance_continuation),
-                                                                                 MAXPRI_KERNEL, &thread);
+           (void *)SCHED(maintenance_continuation), MAXPRI_KERNEL, &thread);
        if (result != KERN_SUCCESS)
                panic("sched_startup");
 
        thread_deallocate(thread);
 
        /*
-        * Yield to the sched_init_thread while it times
-        * a series of context switches back.  It stores
-        * the baseline value in sched_cswtime.
+        * Yield to the sched_init_thread once, to
+        * initialize our own thread after being switched
+        * back to.
         *
         * The current thread is the only other thread
         * active at this point.
         */
-       while (sched_cswtime == 0)
-               thread_block(THREAD_CONTINUE_NULL);
+       thread_block(THREAD_CONTINUE_NULL);
 }
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
-
-static uint64_t                        sched_tick_deadline = 0;
+#if defined(CONFIG_SCHED_TIMESHARE_CORE)
 
+static volatile uint64_t               sched_maintenance_deadline;
+#if defined(CONFIG_TELEMETRY)
+static volatile uint64_t               sched_telemetry_deadline = 0;
+#endif
+static uint64_t                                sched_tick_last_abstime;
+static uint64_t                                sched_tick_delta;
+uint64_t                               sched_tick_max_delta;
 /*
  *     sched_init_thread:
  *
  *     Perform periodic bookkeeping functions about ten
  *     times per second.
  */
-static void
-sched_traditional_tick_continue(void)
+void
+sched_timeshare_maintenance_continue(void)
 {
-       uint64_t                        abstime = mach_absolute_time();
+       uint64_t        sched_tick_ctime, late_time;
+
+       struct sched_update_scan_context scan_context = {
+               .earliest_bg_make_runnable_time = UINT64_MAX,
+               .earliest_normal_make_runnable_time = UINT64_MAX,
+               .earliest_rt_make_runnable_time = UINT64_MAX
+       };
+
+       sched_tick_ctime = mach_absolute_time();        
+
+       if (__improbable(sched_tick_last_abstime == 0)) {
+               sched_tick_last_abstime = sched_tick_ctime;
+               late_time = 0;
+               sched_tick_delta = 1;
+       } else {
+               late_time = sched_tick_ctime - sched_tick_last_abstime;
+               sched_tick_delta = late_time / sched_tick_interval;
+               /* Ensure a delta of 1, since the interval could be slightly
+                * smaller than the sched_tick_interval due to dispatch
+                * latencies.
+                */
+               sched_tick_delta = MAX(sched_tick_delta, 1);
+
+               /* In the event interrupt latencies or platform
+                * idle events that advanced the timebase resulted
+                * in periods where no threads were dispatched,
+                * cap the maximum "tick delta" at SCHED_TICK_MAX_DELTA
+                * iterations.
+                */
+               sched_tick_delta = MIN(sched_tick_delta, SCHED_TICK_MAX_DELTA);
+
+               sched_tick_last_abstime = sched_tick_ctime;
+               sched_tick_max_delta = MAX(sched_tick_delta, sched_tick_max_delta);
+       }
 
-       sched_tick++;
+       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_MAINTENANCE)|DBG_FUNC_START,
+                                                 sched_tick_delta,
+                                                 late_time,
+                                                 0,
+                                                 0,
+                                                 0);
+
+       /* Add a number of pseudo-ticks corresponding to the elapsed interval
+        * This could be greater than 1 if substantial intervals where
+        * all processors are idle occur, which rarely occurs in practice.
+        */
+       
+       sched_tick += sched_tick_delta;
 
        /*
         *  Compute various averages.
         */
-       compute_averages();
+       compute_averages(sched_tick_delta);
 
        /*
         *  Scan the run queues for threads which
         *  may need to be updated.
         */
-       thread_update_scan();
+       SCHED(thread_update_scan)(&scan_context);
 
-       if (sched_tick_deadline == 0)
-               sched_tick_deadline = abstime;
-       
-       clock_deadline_for_periodic_event(sched_tick_interval, abstime,
-                                                                                                               &sched_tick_deadline);
+       rt_runq_scan(&scan_context);
 
-       assert_wait_deadline((event_t)sched_traditional_tick_continue, THREAD_UNINT, sched_tick_deadline);
-       thread_block((thread_continue_t)sched_traditional_tick_continue);
-       /*NOTREACHED*/
-}
+       uint64_t ctime = mach_absolute_time();
 
-#endif /* CONFIG_SCHED_TRADITIONAL */
+       machine_max_runnable_latency(ctime > scan_context.earliest_bg_make_runnable_time ? ctime - scan_context.earliest_bg_make_runnable_time : 0,
+                                                                ctime > scan_context.earliest_normal_make_runnable_time ? ctime - scan_context.earliest_normal_make_runnable_time : 0,
+                                                                ctime > scan_context.earliest_rt_make_runnable_time ? ctime - scan_context.earliest_rt_make_runnable_time : 0);
 
-static uint32_t
-time_individual_cswitch(void)
-{
-       uint32_t switches = 0;
-       uint64_t newtime, starttime;
+       /*
+        * Check to see if the special sched VM group needs attention.
+        */
+       sched_vm_group_maintenance();
 
-       /* Wait for absolute time to increase. */
-       starttime = mach_absolute_time();
-       do {
-               newtime = mach_absolute_time();
-       } while (newtime == starttime);
+       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_MAINTENANCE)|DBG_FUNC_END,
+                                                 sched_pri_shift,
+                                                 sched_background_pri_shift,
+                                                 0,
+                                                 0,
+                                                 0);
 
-       /* Measure one or more context switches until time increases again.
-        * This ensures we get non-zero timings even if absolute time
-        * increases very infrequently compared to CPU clock. */
-       starttime = newtime;
-       do {
-               thread_block(THREAD_CONTINUE_NULL);
-               newtime = mach_absolute_time();
-               ++switches;
-       } while (newtime == starttime);
-       /* Round up. */
-       return (uint32_t) ((newtime - starttime + switches - 1) / switches);
+       assert_wait((event_t)sched_timeshare_maintenance_continue, THREAD_UNINT);
+       thread_block((thread_continue_t)sched_timeshare_maintenance_continue);
+       /*NOTREACHED*/
 }
 
+static uint64_t sched_maintenance_wakeups;
+
 /*
- * Time a series of context switches to determine
- * a baseline.  Toss the high and low and return
- * the one-way value.
+ * Determine if the set of routines formerly driven by a maintenance timer
+ * must be invoked, based on a deadline comparison. Signals the scheduler
+ * maintenance thread on deadline expiration. Must be invoked at an interval
+ * lower than the "sched_tick_interval", currently accomplished by
+ * invocation via the quantum expiration timer and at context switch time.
+ * Performance matters: this routine reuses a timestamp approximating the
+ * current absolute time received from the caller, and should perform
+ * no more than a comparison against the deadline in the common case.
  */
-static uint32_t
-time_cswitch(void)
-{
-       uint32_t        new, hi, low, accum;
-       int                     i, tries = 7, denom;
+void
+sched_timeshare_consider_maintenance(uint64_t ctime) {
+       uint64_t ndeadline, deadline = sched_maintenance_deadline;
+
+       if (__improbable(ctime >= deadline)) {
+               if (__improbable(current_thread() == sched_maintenance_thread))
+                       return;
+               OSMemoryBarrier();
 
-       accum = hi = low = 0;
-       for (i = 0; i < tries; ++i) {
-               new = time_individual_cswitch();
+               ndeadline = ctime + sched_tick_interval;
 
-               if (i == 0)
-                       accum = hi = low = new;
-               else {
-                       if (new < low)
-                               low = new;
-                       else
-                       if (new > hi)
-                               hi = new;
-                       accum += new;
+               if (__probable(__sync_bool_compare_and_swap(&sched_maintenance_deadline, deadline, ndeadline))) {
+                       thread_wakeup((event_t)sched_timeshare_maintenance_continue);
+                       sched_maintenance_wakeups++;
+               }
+       }
+
+#if defined(CONFIG_TELEMETRY)
+       /*
+        * Windowed telemetry is driven by the scheduler.  It should be safe
+        * to call compute_telemetry_windowed() even when windowed telemetry
+        * is disabled, but we should try to avoid doing extra work for no
+        * reason.
+        */
+       if (telemetry_window_enabled) {
+               deadline = sched_telemetry_deadline;
+
+               if (__improbable(ctime >= deadline)) {
+                       ndeadline = ctime + sched_telemetry_interval;
+
+                       if (__probable(__sync_bool_compare_and_swap(&sched_telemetry_deadline, deadline, ndeadline))) {
+                               compute_telemetry_windowed();
+                       }
                }
        }
-       /* Round up. */
-       denom = 2 * (tries - 2);
-       return (accum - hi - low + denom - 1) / denom;
+#endif /* CONFIG_TELEMETRY */
 }
 
+#endif /* CONFIG_SCHED_TIMESHARE_CORE */
+
 void
 sched_init_thread(void (*continuation)(void))
 {
-       sched_cswtime = time_cswitch();
-       assert(sched_cswtime > 0);
+       thread_block(THREAD_CONTINUE_NULL);
 
+       sched_maintenance_thread = current_thread();
        continuation();
 
        /*NOTREACHED*/
 }
 
-#if defined(CONFIG_SCHED_TRADITIONAL)
+#if defined(CONFIG_SCHED_TIMESHARE_CORE)
 
 /*
  *     thread_update_scan / runq_scan:
@@ -4229,14 +4613,47 @@ sched_init_thread(void (*continuation)(void))
 static thread_t                thread_update_array[THREAD_UPDATE_SIZE];
 static int                     thread_update_count = 0;
 
+/* Returns TRUE if thread was added, FALSE if thread_update_array is full */
+boolean_t
+thread_update_add_thread(thread_t thread)
+{
+       if (thread_update_count == THREAD_UPDATE_SIZE)
+               return (FALSE);
+
+       thread_update_array[thread_update_count++] = thread;
+       thread_reference_internal(thread);
+       return (TRUE);
+}
+
+void
+thread_update_process_threads(void)
+{
+       while (thread_update_count > 0) {
+               spl_t   s;
+               thread_t thread = thread_update_array[--thread_update_count];
+               thread_update_array[thread_update_count] = THREAD_NULL;
+
+               s = splsched();
+               thread_lock(thread);
+               if (!(thread->state & (TH_WAIT)) && (SCHED(can_update_priority)(thread))) {
+                       SCHED(update_priority)(thread);
+               }
+               thread_unlock(thread);
+               splx(s);
+
+               thread_deallocate(thread);
+       }
+}
+
 /*
  *     Scan a runq for candidate threads.
  *
  *     Returns TRUE if retry is needed.
  */
-static boolean_t
+boolean_t
 runq_scan(
-       run_queue_t                             runq)
+       run_queue_t                             runq,
+       sched_update_scan_context_t     scan_context)
 {
        register int                    count;
        register queue_t                q;
@@ -4248,11 +4665,18 @@ runq_scan(
                        queue_iterate(q, thread, thread_t, links) {
                                if (            thread->sched_stamp != sched_tick               &&
                                                (thread->sched_mode == TH_MODE_TIMESHARE)       ) {
-                                       if (thread_update_count == THREAD_UPDATE_SIZE)
+                                       if (thread_update_add_thread(thread) == FALSE)
                                                return (TRUE);
+                               }
 
-                                       thread_update_array[thread_update_count++] = thread;
-                                       thread_reference_internal(thread);
+                               if (cpu_throttle_enabled && ((thread->sched_pri <= MAXPRI_THROTTLE) && (thread->base_pri <= MAXPRI_THROTTLE))) {
+                                       if (thread->last_made_runnable_time < scan_context->earliest_bg_make_runnable_time) {
+                                               scan_context->earliest_bg_make_runnable_time = thread->last_made_runnable_time;
+                                       }
+                               } else {
+                                       if (thread->last_made_runnable_time < scan_context->earliest_normal_make_runnable_time) {
+                                               scan_context->earliest_normal_make_runnable_time = thread->last_made_runnable_time;
+                                       }
                                }
 
                                count--;
@@ -4265,64 +4689,7 @@ runq_scan(
        return (FALSE);
 }
 
-static void
-thread_update_scan(void)
-{
-       boolean_t                       restart_needed = FALSE;
-       processor_t                     processor = processor_list;
-       processor_set_t         pset;
-       thread_t                        thread;
-       spl_t                           s;
-
-       do {
-               do {
-                       pset = processor->processor_set;
-
-                       s = splsched();
-                       pset_lock(pset);
-
-                       restart_needed = runq_scan(runq_for_processor(processor));
-
-                       pset_unlock(pset);
-                       splx(s);
-
-                       if (restart_needed)
-                               break;
-
-                       thread = processor->idle_thread;
-                       if (thread != THREAD_NULL && thread->sched_stamp != sched_tick) {
-                               if (thread_update_count == THREAD_UPDATE_SIZE) {
-                                       restart_needed = TRUE;
-                                       break;
-                               }
-
-                               thread_update_array[thread_update_count++] = thread;
-                               thread_reference_internal(thread);
-                       }
-               } while ((processor = processor->processor_list) != NULL);
-
-           /*
-            *  Ok, we now have a collection of candidates -- fix them.
-            */
-           while (thread_update_count > 0) {
-                       thread = thread_update_array[--thread_update_count];
-                       thread_update_array[thread_update_count] = THREAD_NULL;
-
-                       s = splsched();
-                       thread_lock(thread);
-                       if (    !(thread->state & (TH_WAIT))    ) {
-                               if (SCHED(can_update_priority)(thread))
-                                       SCHED(update_priority)(thread);
-                       }
-                       thread_unlock(thread);
-                       splx(s);
-
-                       thread_deallocate(thread);
-           }
-       } while (restart_needed);
-}
-
-#endif /* CONFIG_SCHED_TRADITIONAL */
+#endif /* CONFIG_SCHED_TIMESHARE_CORE */
 
 boolean_t
 thread_eager_preemption(thread_t thread) 
@@ -4344,9 +4711,9 @@ thread_set_eager_preempt(thread_t thread)
        thread->sched_flags |= TH_SFLAG_EAGERPREEMPT;
 
        if (thread == current_thread()) {
-               thread_unlock(thread);
 
-               ast = csw_check(p);
+               ast = csw_check(p, AST_NONE);
+               thread_unlock(thread);
                if (ast != AST_NONE) {
                        (void) thread_block_reason(THREAD_CONTINUE_NULL, NULL, ast);
                }
@@ -4377,6 +4744,7 @@ thread_clear_eager_preempt(thread_t thread)
        thread_unlock(thread);
        splx(x);
 }
+
 /*
  * Scheduling statistics
  */
@@ -4438,43 +4806,52 @@ preemption_enabled(void)
        return (get_preemption_level() == 0 && ml_get_interrupts_enabled());
 }
 
-#if    DEBUG
-static boolean_t
-thread_runnable(
-       thread_t        thread)
-{
-       return ((thread->state & (TH_RUN|TH_WAIT)) == TH_RUN);
+static void
+sched_timer_deadline_tracking_init(void) {
+       nanoseconds_to_absolutetime(TIMER_DEADLINE_TRACKING_BIN_1_DEFAULT, &timer_deadline_tracking_bin_1);
+       nanoseconds_to_absolutetime(TIMER_DEADLINE_TRACKING_BIN_2_DEFAULT, &timer_deadline_tracking_bin_2);
 }
-#endif /* DEBUG */
 
-#if    MACH_KDB
-#include <ddb/db_output.h>
-#define        printf          kdbprintf
-void                   db_sched(void);
 
-void
-db_sched(void)
+kern_return_t
+sched_work_interval_notify(thread_t thread, uint64_t work_interval_id, uint64_t start, uint64_t finish, uint64_t deadline, uint64_t next_start, uint32_t flags)
 {
-       iprintf("Scheduling Statistics:\n");
-       db_indent += 2;
-       iprintf("Thread invocations:  csw %d same %d\n",
-               c_thread_invoke_csw, c_thread_invoke_same);
-#if    MACH_COUNTERS
-       iprintf("Thread block:  calls %d\n",
-               c_thread_block_calls);
-       iprintf("Idle thread:\n\thandoff %d block %d\n",
-               c_idle_thread_handoff,
-               c_idle_thread_block);
-       iprintf("Sched thread blocks:  %d\n", c_sched_thread_block);
-#endif /* MACH_COUNTERS */
-       db_indent -= 2;
-}
+       int urgency;
+       uint64_t urgency_param1, urgency_param2;
+       spl_t s;
 
-#include <ddb/db_output.h>
-void           db_show_thread_log(void);
+       if (work_interval_id == 0) {
+               return (KERN_INVALID_ARGUMENT);
+       }
 
-void
-db_show_thread_log(void)
-{
+       assert(thread == current_thread());
+
+       thread_mtx_lock(thread);
+       if (thread->work_interval_id != work_interval_id) {
+               thread_mtx_unlock(thread);
+               return (KERN_INVALID_ARGUMENT);
+       }
+       thread_mtx_unlock(thread);
+
+       s = splsched();
+       thread_lock(thread);
+       urgency = thread_get_urgency(thread, &urgency_param1, &urgency_param2);
+       thread_unlock(thread);
+       splx(s);
+
+       machine_work_interval_notify(thread, work_interval_id, start, finish, deadline, next_start, urgency, flags);
+       return (KERN_SUCCESS);
+}
+
+void thread_set_options(uint32_t thopt) {
+       spl_t x;
+       thread_t t = current_thread();
+       x = splsched();
+       thread_lock(t);
+       t->options |= thopt;
+       thread_unlock(t);
+       splx(x);
 }
-#endif /* MACH_KDB */