X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/8f6c56a50524aa785f7e596d52dddfb331e18961..743345f9a4b36f7e2f9ba37691e70c50baecb56e:/osfmk/kern/sched_prim.c?ds=sidebyside diff --git a/osfmk/kern/sched_prim.c b/osfmk/kern/sched_prim.c index f85cbcb65..2b2a98d68 100644 --- a/osfmk/kern/sched_prim.c +++ b/osfmk/kern/sched_prim.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2000-2005 Apple Computer, Inc. All rights reserved. + * Copyright (c) 2000-2016 Apple Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * @@ -65,25 +65,30 @@ */ #include -#include - -#include #include #include #include #include +#include #include #include +#include +#include + +#ifdef CONFIG_MACH_APPROXIMATE_TIME +#include +#endif #include +#include #include #include #include #include +#include #include -#include #include #include #include @@ -91,24 +96,49 @@ #include #include #include +#include #include #include #include -#include +#include +#include +#include +#include #include #include #include +#include + #include +#include +#include -#ifdef __ppc__ -#include +#include + +struct rt_queue rt_runq; + +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; @@ -118,112 +148,254 @@ int max_poll_quanta = MAX_POLL_QUANTA; #define SCHED_POLL_YIELD_SHIFT 4 /* 1/16 */ int sched_poll_yield_shift = SCHED_POLL_YIELD_SHIFT; -uint64_t max_unsafe_computation; -uint32_t sched_safe_duration; uint64_t max_poll_computation; +uint64_t max_unsafe_computation; +uint64_t sched_safe_duration; + +#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_TIMESHARE_CORE */ + +uint32_t thread_depress_time; +uint32_t default_timeshare_computation; +uint32_t default_timeshare_constraint; uint32_t max_rt_quantum; uint32_t min_rt_quantum; -uint32_t sched_cswtime; - -static uint32_t delay_idle_limit, delay_idle_spin; -static processor_t delay_idle( - processor_t processor, - thread_t self); +#if defined(CONFIG_SCHED_TIMESHARE_CORE) unsigned sched_tick; uint32_t sched_tick_interval; -uint32_t sched_pri_shift; +uint32_t sched_pri_shifts[TH_BUCKET_MAX]; +uint32_t sched_fixed_shift; + +uint32_t sched_decay_usage_age_factor = 1; /* accelerate 5/8^n usage aging */ + +/* 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; + +/* 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 */ + +uint64_t timer_deadline_tracking_bin_1; +uint64_t timer_deadline_tracking_bin_2; + +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + +thread_t sched_maintenance_thread; + + +uint64_t sched_one_second_interval; /* Forwards */ -void wait_queues_init(void); -static void load_shift_init(void); +#if defined(CONFIG_SCHED_TIMESHARE_CORE) + +static void load_shift_init(void); +static void preempt_pri_init(void); -static thread_t choose_thread( - processor_set_t pset, +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + +static thread_t thread_select( + thread_t thread, + processor_t processor, + ast_t reason); + +#if CONFIG_SCHED_IDLE_IN_PLACE +static thread_t thread_select_idle( + thread_t thread, + processor_t processor); +#endif + +thread_t processor_idle( + thread_t 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 void +sched_realtime_init(void); + +static void +sched_realtime_timebase_init(void); + +static void +sched_timer_deadline_tracking_init(void); #if DEBUG -static -boolean_t thread_runnable( - thread_t thread); +extern int debug_task; +#define TLOG(a, fmt, args...) if(debug_task & a) kprintf(fmt, ## args) +#else +#define TLOG(a, fmt, args...) do {} while (0) +#endif -#endif /*DEBUG*/ +static processor_t +thread_bind_internal( + thread_t thread, + processor_t processor); +static void +sched_vm_group_maintenance(void); -/* - * 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 - * - */ +#if defined(CONFIG_SCHED_TIMESHARE_CORE) +int8_t sched_load_shifts[NRQS]; +bitmap_t sched_preempt_pri[BITMAP_LEN(NRQS)]; +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + +const struct sched_dispatch_table *sched_current_dispatch = NULL; /* - * Waiting protocols and implementation: - * - * Each thread may be waiting for exactly one event; this event - * is set using assert_wait(). That thread may be awakened either - * by performing a thread_wakeup_prim() on its event, - * or by directly waking that thread up with clear_wait(). - * - * The implementation of wait events uses a hash table. Each - * bucket is queue of threads having the same hash function - * value; the chain for the queue (linked list) is the run queue - * field. [It is not possible to be waiting and runnable at the - * same time.] - * - * Locks on both the thread and on the hash buckets govern the - * wait event field and the queue chain field. Because wakeup - * operations only have the event as an argument, the event hash - * bucket must be locked before any thread. - * - * Scheduling operations may also occur at interrupt level; therefore, - * interrupts below splsched() must be prevented when holding - * thread or hash bucket locks. + * Statically allocate a buffer to hold the longest possible + * scheduler description string, as currently implemented. + * bsd/kern/kern_sysctl.c has a corresponding definition in bsd/ + * to export to userspace via sysctl(3). If either version + * changes, update the other. * - * The wait event hash table declarations are as follows: + * Note that in addition to being an upper bound on the strings + * in the kernel, it's also an exact parameter to PE_get_default(), + * which interrogates the device tree on some platforms. That + * API requires the caller know the exact size of the device tree + * property, so we need both a legacy size (32) and the current size + * (48) to deal with old and new device trees. The device tree property + * is similarly padded to a fixed size so that the same kernel image + * can run on multiple devices with different schedulers configured + * in the device tree. */ +char sched_string[SCHED_STRING_MAX_LENGTH]; -#define NUMQUEUES 59 +uint32_t sched_debug_flags; -struct wait_queue wait_queues[NUMQUEUES]; +/* Global flag which indicates whether Background Stepper Context is enabled */ +static int cpu_throttle_enabled = 1; -#define wait_hash(event) \ - ((((int)(event) < 0)? ~(int)(event): (int)(event)) % NUMQUEUES) +void +sched_init(void) +{ + char sched_arg[SCHED_STRING_MAX_LENGTH] = { '\0' }; + + /* Check for runtime selection of the scheduler algorithm */ + if (!PE_parse_boot_argn("sched", sched_arg, sizeof (sched_arg))) { + /* If no boot-args override, look in device tree */ + if (!PE_get_default("kern.sched", sched_arg, + SCHED_STRING_MAX_LENGTH)) { + sched_arg[0] = '\0'; + } + } -int8_t sched_load_shifts[NRQS]; + + 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, sched_traditional_dispatch.sched_name)) { + sched_current_dispatch = &sched_traditional_dispatch; + } else if (0 == strcmp(sched_arg, sched_traditional_with_pset_runqueue_dispatch.sched_name)) { + sched_current_dispatch = &sched_traditional_with_pset_runqueue_dispatch; +#endif +#if defined(CONFIG_SCHED_PROTO) + } else if (0 == strcmp(sched_arg, sched_proto_dispatch.sched_name)) { + sched_current_dispatch = &sched_proto_dispatch; +#endif +#if defined(CONFIG_SCHED_GRRR) + } else if (0 == strcmp(sched_arg, sched_grrr_dispatch.sched_name)) { + sched_current_dispatch = &sched_grrr_dispatch; +#endif +#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_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; +#elif defined(CONFIG_SCHED_GRRR) + sched_current_dispatch = &sched_grrr_dispatch; +#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_realtime_init(); + ast_init(); + sched_timer_deadline_tracking_init(); + + SCHED(pset_init)(&pset0); + SCHED(processor_init)(master_processor); +} void -sched_init(void) +sched_timebase_init(void) +{ + uint64_t abstime; + + clock_interval_to_absolutetime_interval(1, NSEC_PER_SEC, &abstime); + sched_one_second_interval = abstime; + + SCHED(timebase_init)(); + sched_realtime_timebase_init(); +} + +#if defined(CONFIG_SCHED_TIMESHARE_CORE) + +void +sched_timeshare_init(void) { /* * Calculate the timeslicing quantum @@ -235,18 +407,19 @@ sched_init(void) printf("standard timeslicing quantum is %d us\n", std_quantum_us); - sched_safe_duration = (2 * max_unsafe_quanta / default_preemption_rate) * - (1 << SCHED_TICK_SHIFT); + 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); - wait_queues_init(); load_shift_init(); - pset_init(&default_pset); + preempt_pri_init(); sched_tick = 0; - ast_init(); } void -sched_timebase_init(void) +sched_timeshare_timebase_init(void) { uint64_t abstime; uint32_t shift; @@ -255,29 +428,24 @@ sched_timebase_init(void) clock_interval_to_absolutetime_interval( std_quantum_us, NSEC_PER_USEC, &abstime); assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); - std_quantum = abstime; + std_quantum = (uint32_t)abstime; /* smallest remaining quantum (250 us) */ clock_interval_to_absolutetime_interval(250, NSEC_PER_USEC, &abstime); assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); - min_std_quantum = abstime; - - /* smallest rt computaton (50 us) */ - clock_interval_to_absolutetime_interval(50, NSEC_PER_USEC, &abstime); - assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); - min_rt_quantum = abstime; + min_std_quantum = (uint32_t)abstime; - /* maximum rt computation (50 ms) */ + /* quantum for background tasks */ clock_interval_to_absolutetime_interval( - 50, 1000*NSEC_PER_USEC, &abstime); + bg_quantum_us, NSEC_PER_USEC, &abstime); assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); - max_rt_quantum = abstime; + bg_quantum = (uint32_t)abstime; /* scheduler tick interval */ clock_interval_to_absolutetime_interval(USEC_PER_SEC >> SCHED_TICK_SHIFT, NSEC_PER_USEC, &abstime); assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); - sched_tick_interval = abstime; + sched_tick_interval = (uint32_t)abstime; /* * Compute conversion factor from usage to @@ -286,31 +454,52 @@ sched_timebase_init(void) abstime = (abstime * 5) / 3; for (shift = 0; abstime > BASEPRI_DEFAULT; ++shift) abstime >>= 1; - sched_pri_shift = shift; + sched_fixed_shift = shift; - max_unsafe_computation = max_unsafe_quanta * std_quantum; - max_poll_computation = max_poll_quanta * std_quantum; + for (uint32_t i = 0 ; i < TH_BUCKET_MAX ; i++) + sched_pri_shifts[i] = INT8_MAX; - /* delay idle constant(s) (60, 1 us) */ - clock_interval_to_absolutetime_interval(60, NSEC_PER_USEC, &abstime); - assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); - delay_idle_limit = abstime; + max_unsafe_computation = ((uint64_t)max_unsafe_quanta) * std_quantum; + sched_safe_duration = 2 * ((uint64_t)max_unsafe_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; - clock_interval_to_absolutetime_interval(1, NSEC_PER_USEC, &abstime); - assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); - delay_idle_spin = abstime; } -void -wait_queues_init(void) +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + +static void +sched_realtime_init(void) { - register int i; + rt_lock_init(); + + rt_runq.count = 0; + queue_init(&rt_runq.queue); +} + +static void +sched_realtime_timebase_init(void) +{ + uint64_t abstime; + + /* smallest rt computaton (50 us) */ + clock_interval_to_absolutetime_interval(50, NSEC_PER_USEC, &abstime); + assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); + min_rt_quantum = (uint32_t)abstime; + + /* maximum rt computation (50 ms) */ + clock_interval_to_absolutetime_interval( + 50, 1000*NSEC_PER_USEC, &abstime); + assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); + max_rt_quantum = (uint32_t)abstime; - for (i = 0; i < NUMQUEUES; i++) { - wait_queue_init(&wait_queues[i], SYNC_POLICY_FIFO); - } } +#if defined(CONFIG_SCHED_TIMESHARE_CORE) + /* * Set up values for timeshare * loading factors. @@ -321,14 +510,59 @@ 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 (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; } } +static void +preempt_pri_init(void) +{ + bitmap_t *p = sched_preempt_pri; + + for (int i = BASEPRI_FOREGROUND; i < MINPRI_KERNEL; ++i) + bitmap_set(p, i); + + for (int i = BASEPRI_PREEMPT; i <= MAXPRI; ++i) + bitmap_set(p, i); +} + +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + /* * Thread wait timer expiration. */ @@ -340,6 +574,8 @@ thread_timer_expire( thread_t thread = p0; spl_t s; + assert_thread_magic(thread); + s = splsched(); thread_lock(thread); if (--thread->wait_timer_active == 0) { @@ -352,92 +588,33 @@ thread_timer_expire( splx(s); } -/* - * 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->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->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); -} - /* * 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. + * Set wait_result. */ thread->wait_result = wresult; /* - * Cancel pending wait timer. + * Cancel pending wait timer. */ if (thread->wait_timer_is_set) { if (timer_call_cancel(&thread->wait_timer)) @@ -446,49 +623,115 @@ thread_unblock( } /* - * Update scheduling state. + * Update scheduling state: not waiting, + * set running. */ thread->state &= ~(TH_WAIT|TH_UNINT); 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 the runnable thread count */ + new_run_count = sched_run_incr(thread); + } else { /* - * Mark unblocked if call out. + * Either the thread is idling in place on another processor, + * or it hasn't finished context switching yet. */ - if (thread->options & TH_OPT_CALLOUT) - call_thread_unblock(); +#if CONFIG_SCHED_IDLE_IN_PLACE + if (thread->state & TH_IDLE) { + processor_t processor = thread->last_processor; + if (processor != current_processor()) + machine_signal_idle(processor); + } +#else + assert((thread->state & TH_IDLE) == 0); +#endif /* - * Update pset run counts. + * The run count is only dropped after the context switch completes + * and the thread is still waiting, so we should not run_incr here */ - pset_run_incr(thread->processor_set); - if (thread->sched_mode & TH_MODE_TIMESHARE) - pset_share_incr(thread->processor_set); + new_run_count = sched_run_buckets[TH_BUCKET_RUN]; } - else - result = TRUE; + /* * 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; + if (thread->sched_mode == TH_MODE_REALTIME) { + 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, - (int)thread, (int)thread->sched_pri, 0, 0, 0); + (uintptr_t)thread_tid(thread), thread->sched_pri, thread->wait_result, + sched_run_buckets[TH_BUCKET_RUN], 0); - return (result); + DTRACE_SCHED2(wakeup, struct thread *, thread, struct proc *, thread->task->bsd_info); + + return (ready_for_runq); } /* @@ -498,27 +741,36 @@ 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_magic(thread); + assert(thread->at_safe_point == FALSE); assert(thread->wait_event == NO_EVENT64); - assert(thread->wait_queue == WAIT_QUEUE_NULL); + assert(thread->waitq == NULL); + + assert(!(thread->state & (TH_TERMINATE|TH_TERMINATE2))); + assert(thread->state & TH_WAIT); - if ((thread->state & (TH_WAIT|TH_TERMINATE)) == TH_WAIT) { - if (!thread_unblock(thread, wresult)) - thread_setrun(thread, SCHED_PREEMPT | SCHED_TAILQ); - return (KERN_SUCCESS); + if (thread_unblock(thread, wresult)) { +#if SCHED_TRACE_THREAD_WAKEUPS + backtrace(&thread->thread_wakeup_bt[0], + (sizeof(thread->thread_wakeup_bt)/sizeof(uintptr_t))); +#endif + thread_setrun(thread, SCHED_PREEMPT | SCHED_TAILQ); } - return (KERN_NOT_WAITING); + return (KERN_SUCCESS); } /* @@ -538,6 +790,8 @@ thread_mark_wait_locked( { boolean_t at_safe_point; + assert(!(thread->state & (TH_WAIT|TH_IDLE|TH_UNINT|TH_TERMINATE2))); + /* * The thread may have certain types of interrupts/aborts masked * off. Even if the wait location says these types of interrupts @@ -550,16 +804,20 @@ thread_mark_wait_locked( at_safe_point = (interruptible == THREAD_ABORTSAFE); if ( interruptible == THREAD_UNINT || - !(thread->state & TH_ABORT) || + !(thread->sched_flags & TH_SFLAG_ABORT) || (!at_safe_point && - (thread->state & TH_ABORT_SAFELY)) ) { + (thread->sched_flags & TH_SFLAG_ABORTSAFELY))) { + + if ( !(thread->state & TH_TERMINATE)) + DTRACE_SCHED(sleep); + thread->state |= (interruptible) ? TH_WAIT : (TH_WAIT | TH_UNINT); thread->at_safe_point = at_safe_point; return (thread->wait_result = THREAD_WAITING); } else - if (thread->state & TH_ABORT_SAFELY) - thread->state &= ~(TH_ABORT|TH_ABORT_SAFELY); + if (thread->sched_flags & TH_SFLAG_ABORTSAFELY) + thread->sched_flags &= ~TH_SFLAG_ABORTED_MASK; return (thread->wait_result = THREAD_INTERRUPTED); } @@ -609,7 +867,7 @@ assert_wait_possible(void) thread = current_thread(); - return (thread == NULL || wait_queue_assert_possible(thread)); + return (thread == NULL || waitq_wait_possible(thread)); } /* @@ -623,14 +881,28 @@ 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_OR_PERM(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); +} + +/* + * assert_wait_queue: + * + * Return the global waitq for the specified event + */ +struct waitq * +assert_wait_queue( + event_t event) +{ + return global_eventq(event); } wait_result_t @@ -642,26 +914,79 @@ 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); - thread_lock(thread); + waitq_lock(waitq); clock_interval_to_deadline(interval, scale_factor, &deadline); - wresult = wait_queue_assert_wait64_locked(wqueue, (uint32_t)event, - interruptible, deadline, thread); - thread_unlock(thread); - wait_queue_unlock(wqueue); + KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE, + MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAIT)|DBG_FUNC_NONE, + VM_KERNEL_UNSLIDE_OR_PERM(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); + + waitq_unlock(waitq); splx(s); + return wresult; +} + +wait_result_t +assert_wait_timeout_with_leeway( + event_t event, + wait_interrupt_t interruptible, + wait_timeout_urgency_t urgency, + uint32_t interval, + uint32_t leeway, + uint32_t scale_factor) +{ + thread_t thread = current_thread(); + wait_result_t wresult; + uint64_t deadline; + uint64_t abstime; + uint64_t slop; + uint64_t now; + spl_t s; + + 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(); + waitq_lock(waitq); + + KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE, + MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAIT)|DBG_FUNC_NONE, + VM_KERNEL_UNSLIDE_OR_PERM(event), interruptible, deadline, 0, 0); - return (wresult); + wresult = waitq_assert_wait64_locked(waitq, CAST_EVENT64_T(event), + interruptible, + urgency, deadline, slop, + thread); + + waitq_unlock(waitq); + splx(s); + return wresult; } wait_result_t @@ -672,161 +997,112 @@ assert_wait_deadline( { thread_t thread = current_thread(); wait_result_t wresult; - wait_queue_t wqueue; 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); - thread_lock(thread); + waitq_lock(waitq); - wresult = wait_queue_assert_wait64_locked(wqueue, (uint32_t)event, - interruptible, deadline, thread); + KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE, + MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAIT)|DBG_FUNC_NONE, + VM_KERNEL_UNSLIDE_OR_PERM(event), interruptible, deadline, 0, 0); - thread_unlock(thread); - wait_queue_unlock(wqueue); + wresult = waitq_assert_wait64_locked(waitq, CAST_EVENT64_T(event), + interruptible, + TIMEOUT_URGENCY_SYS_NORMAL, deadline, + TIMEOUT_NO_LEEWAY, thread); + 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 +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; - - res = assert_wait(event, interruptible); - if (res == THREAD_WAITING) { - simple_unlock(lock); - res = thread_block(THREAD_CONTINUE_NULL); - simple_lock(lock); - } - return res; -} + thread_t thread = current_thread(); + wait_result_t wresult; + spl_t s; + if (__improbable(event == NO_EVENT)) + panic("%s() called with NO_EVENT", __func__); -/* - * 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) -{ - wait_result_t res; + struct waitq *waitq; + waitq = global_eventq(event); - res = assert_wait(event, interruptible); - if (res == THREAD_WAITING) { - usimple_unlock(lock); - res = thread_block(THREAD_CONTINUE_NULL); - usimple_lock(lock); - } - return res; -} + s = splsched(); + waitq_lock(waitq); -/* - * thread_sleep_mutex: - * - * Cause the current thread to wait until the specified event - * occurs. The specified mutex is unlocked before releasing - * the cpu. The mutex will be re-acquired before returning. - * - * JMM - Add hint to make sure mutex is available before rousting - */ -wait_result_t -thread_sleep_mutex( - event_t event, - mutex_t *mutex, - wait_interrupt_t interruptible) -{ - wait_result_t res; + KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE, + MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAIT)|DBG_FUNC_NONE, + VM_KERNEL_UNSLIDE_OR_PERM(event), interruptible, deadline, 0, 0); - res = assert_wait(event, interruptible); - if (res == THREAD_WAITING) { - mutex_unlock(mutex); - res = thread_block(THREAD_CONTINUE_NULL); - mutex_lock(mutex); - } - return res; + wresult = waitq_assert_wait64_locked(waitq, CAST_EVENT64_T(event), + interruptible, + urgency, deadline, leeway, + thread); + waitq_unlock(waitq); + splx(s); + return wresult; } - + /* - * thread_sleep_mutex_deadline: + * thread_isoncpu: * - * Cause the current thread to wait until the specified event - * (or deadline) occurs. The specified mutex is unlocked before - * releasing the cpu. The mutex 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_mutex_deadline( - event_t event, - mutex_t *mutex, - uint64_t deadline, - 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_deadline(event, interruptible, deadline); - if (res == THREAD_WAITING) { - mutex_unlock(mutex); - res = thread_block(THREAD_CONTINUE_NULL); - mutex_lock(mutex); - } - 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_sleep_lock_write: - * - * 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. - */ -wait_result_t -thread_sleep_lock_write( - event_t event, - lock_t *lock, - wait_interrupt_t interruptible) -{ - wait_result_t res; + /* + * 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); - res = assert_wait(event, interruptible); - if (res == THREAD_WAITING) { - lock_write_done(lock); - res = thread_block(THREAD_CONTINUE_NULL); - lock_write(lock); - } - return res; + /* + * 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 @@ -836,16 +1112,20 @@ 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; + spl_t s = splsched(); + boolean_t oncpu; - s = splsched(); wake_lock(thread); + thread_lock(thread); while (thread->state & TH_SUSP) { thread->wake_active = TRUE; + thread_unlock(thread); + wresult = assert_wait(&thread->wake_active, THREAD_ABORTSAFE); wake_unlock(thread); splx(s); @@ -858,21 +1138,24 @@ thread_stop( s = splsched(); wake_lock(thread); + thread_lock(thread); } - thread_lock(thread); thread->state |= TH_SUSP; - while (thread->state & TH_RUN) { - processor_t processor = thread->last_processor; - - if ( processor != PROCESSOR_NULL && - processor->state == PROCESSOR_RUNNING && - 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_unlock(thread); + } thread->wake_active = TRUE; + thread_unlock(thread); + wresult = assert_wait(&thread->wake_active, THREAD_ABORTSAFE); wake_unlock(thread); splx(s); @@ -893,6 +1176,13 @@ 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); } @@ -914,23 +1204,19 @@ 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; if (thread->wake_active) { thread->wake_active = FALSE; thread_unlock(thread); + + thread_wakeup(&thread->wake_active); wake_unlock(thread); splx(s); - thread_wakeup(&thread->wake_active); return; } } @@ -948,24 +1234,36 @@ 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->state == PROCESSOR_RUNNING && - processor->active_thread == thread ) + if (oncpu) { + assert(thread->state & TH_RUN); + processor = thread->chosen_processor; cause_ast_check(processor); - thread_unlock(thread); + } thread->wake_active = TRUE; + thread_unlock(thread); + wresult = assert_wait(&thread->wake_active, THREAD_UNINT); wake_unlock(thread); splx(s); @@ -1004,35 +1302,35 @@ clear_wait_internal( thread_t thread, wait_result_t wresult) { - wait_queue_t wq = thread->wait_queue; - int i = LockTimeOut; - + uint32_t i = LockTimeOutUsec; + 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) { + if (!waitq_pull_thread_locked(waitq, thread)) { thread_unlock(thread); delay(1); - + if (i > 0 && !machine_timeout_suspended()) + i--; 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)); - } while (--i > 0); + /* 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); - panic("clear_wait_internal: deadlock: thread=0x%x, wq=0x%x, cpu=%d\n", - thread, wq, cpu_number()); + panic("clear_wait_internal: deadlock: thread=%p, wq=%p, cpu=%d\n", + thread, waitq, cpu_number()); return (KERN_FAILURE); } @@ -1074,25 +1372,79 @@ clear_wait( */ kern_return_t thread_wakeup_prim( - event_t event, - boolean_t one_thread, - wait_result_t result) + event_t event, + boolean_t one_thread, + wait_result_t result) { - register wait_queue_t wq; - register int index; + if (__improbable(event == NO_EVENT)) + panic("%s() called with NO_EVENT", __func__); + + struct waitq *wq = global_eventq(event); - index = wait_hash(event); - wq = &wait_queues[index]; if (one_thread) - return (wait_queue_wakeup_one(wq, event, result)); + return waitq_wakeup64_one(wq, CAST_EVENT64_T(event), result, WAITQ_ALL_PRIORITIES); else - return (wait_queue_wakeup_all(wq, event, result)); + return waitq_wakeup64_all(wq, CAST_EVENT64_T(event), result, WAITQ_ALL_PRIORITIES); +} + +/* + * Wakeup a specified thread if and only if it's waiting for this event + */ +kern_return_t +thread_wakeup_thread( + event_t event, + thread_t thread) +{ + if (__improbable(event == NO_EVENT)) + panic("%s() called with NO_EVENT", __func__); + + struct waitq *wq = global_eventq(event); + + return waitq_wakeup64_thread(wq, CAST_EVENT64_T(event), thread, THREAD_AWAKENED); +} + +/* + * Wakeup a thread waiting on an event and promote it to a priority. + * + * Requires woken thread to un-promote itself when done. + */ +kern_return_t +thread_wakeup_one_with_pri( + event_t event, + int priority) +{ + if (__improbable(event == NO_EVENT)) + panic("%s() called with NO_EVENT", __func__); + + struct waitq *wq = global_eventq(event); + + return waitq_wakeup64_one(wq, CAST_EVENT64_T(event), THREAD_AWAKENED, priority); +} + +/* + * Wakeup a thread waiting on an event, + * promote it to a priority, + * and return a reference to the woken thread. + * + * Requires woken thread to un-promote itself when done. + */ +thread_t +thread_wakeup_identify(event_t event, + int priority) +{ + if (__improbable(event == NO_EVENT)) + panic("%s() called with NO_EVENT", __func__); + + struct waitq *wq = global_eventq(event); + + return waitq_wakeup64_identify(wq, CAST_EVENT64_T(event), THREAD_AWAKENED, priority); } /* * thread_bind: * - * Force a thread to execute on the specified processor. + * 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. @@ -1101,1141 +1453,2497 @@ thread_wakeup_prim( */ processor_t thread_bind( - register thread_t thread, - processor_t processor) + processor_t processor) { + thread_t self = current_thread(); processor_t prev; - run_queue_t runq = RUN_QUEUE_NULL; spl_t s; s = splsched(); - thread_lock(thread); - prev = thread->bound_processor; - if (prev != PROCESSOR_NULL) - runq = run_queue_remove(thread); + thread_lock(self); - thread->bound_processor = processor; + prev = thread_bind_internal(self, processor); - if (runq != RUN_QUEUE_NULL) - thread_setrun(thread, SCHED_PREEMPT | SCHED_TAILQ); - thread_unlock(thread); + thread_unlock(self); splx(s); return (prev); } -struct { - uint32_t idle_pset_last, - idle_pset_any, - idle_bound; +/* + * 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; + + /* */ + 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); - uint32_t pset_self, - pset_last, - pset_other, - bound_self, - bound_other; + 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); - uint32_t realtime_self, - realtime_last, - realtime_other; + prev = thread->bound_processor; + thread->bound_processor = processor; - uint32_t missed_realtime, - missed_other; -} dispatch_counts; + return (prev); +} /* - * Select a thread for the current processor to run. + * thread_vm_bind_group_add: * - * May select the current thread, which must be locked. + * 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). */ -thread_t -thread_select( - register processor_t processor) + +/* + * 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) { - register thread_t thread; - processor_set_t pset; - boolean_t other_runnable; + thread_t self = current_thread(); - /* - * Check for other non-idle runnable threads. - */ - pset = processor->processor_set; - thread = processor->active_thread; + thread_reference_internal(self); + self->options |= TH_OPT_SCHED_VM_GROUP; - /* Update the thread's priority */ - if (thread->sched_stamp != sched_tick) - update_priority(thread); + 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); - processor->current_pri = thread->sched_pri; + thread_bind(master_processor); - simple_lock(&pset->sched_lock); - - other_runnable = processor->runq.count > 0 || pset->runq.count > 0; - - if ( thread->state == TH_RUN && - thread->processor_set == pset && - (thread->bound_processor == PROCESSOR_NULL || - thread->bound_processor == processor) ) { - if ( thread->sched_pri >= BASEPRI_RTQUEUES && - first_timeslice(processor) ) { - if (pset->runq.highq >= BASEPRI_RTQUEUES) { - register run_queue_t runq = &pset->runq; - register queue_t q; - - q = runq->queues + runq->highq; - if (((thread_t)q->next)->realtime.deadline < - processor->deadline) { - thread = (thread_t)q->next; - ((queue_entry_t)thread)->next->prev = q; - q->next = ((queue_entry_t)thread)->next; - thread->runq = RUN_QUEUE_NULL; - assert(thread->sched_mode & TH_MODE_PREEMPT); - runq->count--; runq->urgency--; - if (queue_empty(q)) { - if (runq->highq != IDLEPRI) - clrbit(MAXPRI - runq->highq, runq->bitmap); - runq->highq = MAXPRI - ffsbit(runq->bitmap); - } - } - } + /* Switch to bound processor if not already there */ + thread_block(THREAD_CONTINUE_NULL); +} - processor->deadline = thread->realtime.deadline; +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); - simple_unlock(&pset->sched_lock); + s = splsched(); - return (thread); + 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 ( (!other_runnable || - (processor->runq.highq < thread->sched_pri && - pset->runq.highq < thread->sched_pri)) ) { + if (high_latency_observed && runnable_and_not_on_runq_observed) { + /* All the things we are looking for are true, stop looking */ + break; + } + } - /* I am the highest priority runnable (non-idle) thread */ + splx(s); - processor->deadline = UINT64_MAX; + 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); - simple_unlock(&pset->sched_lock); + 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 */ + } + } - return (thread); + if (removed) { + thread_run_queue_reinsert(thread, SCHED_PREEMPT | SCHED_TAILQ); + } + thread_unlock(thread); } + splx(s); } - if (other_runnable) - thread = choose_thread(pset, processor); - else { - /* - * Nothing is runnable, so set this processor idle if it - * was running. Return its idle thread. - */ - if (processor->state == PROCESSOR_RUNNING) { - remqueue(&pset->active_queue, (queue_entry_t)processor); - processor->state = PROCESSOR_IDLE; + simple_unlock(&sched_vm_group_list_lock); +} - enqueue_tail(&pset->idle_queue, (queue_entry_t)processor); - pset->idle_count++; - } +/* 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. + */ - processor->deadline = UINT64_MAX; +#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; - thread = processor->idle_thread; + /* 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; + + qe_foreach_element(sprocessor, &cpset->active_queue, processor_queue) { + 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; + } } - simple_unlock(&pset->sched_lock); +smt_balance_exit: + pset_unlock(cpset); - return (thread); + 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__ */ /* - * Perform a context switch and start executing the new thread. + * thread_select: * - * Returns FALSE on failure, and the thread is re-dispatched. + * Select a new thread for the current processor to execute. * - * Called at splsched. + * May select the current thread, which must be locked. */ - -#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 - -boolean_t -thread_invoke( - register thread_t old_thread, - register thread_t new_thread, +static thread_t +thread_select( + thread_t thread, + processor_t processor, ast_t reason) { - thread_continue_t new_cont, continuation = old_thread->continuation; - void *new_param, *parameter = old_thread->parameter; - processor_t processor; - thread_t prev_thread; - - if (get_preemption_level() != 0) - panic("thread_invoke: preemption_level %d\n", - get_preemption_level()); + processor_set_t pset = processor->processor_set; + thread_t new_thread = THREAD_NULL; - assert(old_thread == current_thread()); + assert(processor == current_processor()); + assert((thread->state & (TH_RUN|TH_TERMINATE2)) == TH_RUN); - /* - * Mark thread interruptible. - */ - thread_lock(new_thread); - new_thread->state &= ~TH_UNINT; + do { + /* + * Update the priority. + */ + if (SCHED(can_update_priority)(thread)) + SCHED(update_priority)(thread); + + processor->current_pri = thread->sched_pri; + processor->current_thmode = thread->sched_mode; + processor->current_sfi_class = thread->sfi_class; - assert(thread_runnable(new_thread)); + pset_lock(pset); - /* - * Allow time constraint threads to hang onto - * a stack. - */ - if ( (old_thread->sched_mode & TH_MODE_REALTIME) && - !old_thread->reserved_stack ) { - old_thread->reserved_stack = old_thread->kernel_stack; - } + assert(processor->state != PROCESSOR_OFF_LINE); - if (continuation != NULL) { - if (!new_thread->kernel_stack) { + if (!processor->is_recommended) { /* - * If the old thread is using a privileged stack, - * check to see whether we can exchange it with - * that of the new thread. + * 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 ( old_thread->kernel_stack == old_thread->reserved_stack && - !new_thread->reserved_stack) - goto need_stack; - + if (!SCHED(processor_bound_count)(processor)) { + goto idle; + } + } else if (processor->processor_primary != processor) { /* - * Context switch by performing a stack handoff. + * 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. */ - new_cont = new_thread->continuation; - new_thread->continuation = NULL; - new_param = new_thread->parameter; - new_thread->parameter = NULL; + if (!SCHED(processor_bound_count)(processor) && !queue_empty(&pset->idle_queue) && !rt_runq.count) { + goto idle; + } + } - processor = current_processor(); - processor->active_thread = new_thread; - processor->current_pri = new_thread->sched_pri; - new_thread->last_processor = processor; - ast_context(new_thread); - thread_unlock(new_thread); - - current_task()->csw++; + rt_lock_lock(); - old_thread->reason = reason; + /* + * Test to see if the current thread should continue + * 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, 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. + */ - processor->last_dispatch = mach_absolute_time(); - timer_event((uint32_t)processor->last_dispatch, - &new_thread->system_timer); - - thread_done(old_thread, new_thread, 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) { + thread_t next_rt = qe_queue_first(&rt_runq.queue, struct thread, runq_links); - machine_stack_handoff(old_thread, new_thread); + assert(next_rt->runq == THREAD_ON_RT_RUNQ); - thread_begin(new_thread, processor); + 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; + } + } - /* - * Now dispatch the old thread. - */ - thread_dispatch(old_thread); + /* This is still the best RT thread to run. */ + processor->deadline = thread->realtime.deadline; - counter_always(c_thread_invoke_hits++); + rt_lock_unlock(); + pset_unlock(pset); - funnel_refunnel_check(new_thread, 2); - (void) spllo(); + return (thread); + } - assert(new_cont); - call_continuation(new_cont, new_param, new_thread->wait_result); - /*NOTREACHED*/ - } - else - if (new_thread == old_thread) { - /* same thread but with continuation */ - counter(++c_thread_invoke_same); - thread_unlock(new_thread); + 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; - funnel_refunnel_check(new_thread, 3); - (void) spllo(); + rt_lock_unlock(); + pset_unlock(pset); - call_continuation(continuation, parameter, new_thread->wait_result); - /*NOTREACHED*/ + return (thread); + } } - } - else { - /* - * Check that the new thread has a stack - */ - if (!new_thread->kernel_stack) { -need_stack: - if (!stack_alloc_try(new_thread)) { - counter_always(c_thread_invoke_misses++); - thread_unlock(new_thread); - thread_stack_enqueue(new_thread); - return (FALSE); - } - } - else - if (new_thread == old_thread) { - counter(++c_thread_invoke_same); - thread_unlock(new_thread); - return (TRUE); - } - } - - /* - * Context switch by full context save. - */ - processor = current_processor(); - processor->active_thread = new_thread; - processor->current_pri = new_thread->sched_pri; - new_thread->last_processor = processor; - ast_context(new_thread); - assert(thread_runnable(new_thread)); - thread_unlock(new_thread); - - counter_always(c_thread_invoke_csw++); - current_task()->csw++; - assert(old_thread->runq == RUN_QUEUE_NULL); - old_thread->reason = reason; - - processor->last_dispatch = mach_absolute_time(); - timer_event((uint32_t)processor->last_dispatch, &new_thread->system_timer); + /* 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 = qe_queue_first(&rt_runq.queue, struct thread, runq_links); - thread_done(old_thread, new_thread, processor); + assert(next_rt->runq == THREAD_ON_RT_RUNQ); - /* - * This is where we actually switch register context, - * and address space if required. Control will not - * return here immediately. - */ - prev_thread = machine_switch_context(old_thread, continuation, new_thread); + if (__probable((next_rt->bound_processor == PROCESSOR_NULL || + (next_rt->bound_processor == processor)))) { +pick_new_rt_thread: + new_thread = qe_dequeue_head(&rt_runq.queue, struct thread, runq_links); - /* - * We are still old_thread, possibly on a different processor, - * and new_thread is now stale. - */ - thread_begin(old_thread, old_thread->last_processor); + new_thread->runq = PROCESSOR_NULL; + SCHED_STATS_RUNQ_CHANGE(&rt_runq.runq_stats, rt_runq.count); + rt_runq.count--; - /* - * Now dispatch the thread which resumed us. - */ - thread_dispatch(prev_thread); + processor->deadline = new_thread->realtime.deadline; - if (continuation) { - funnel_refunnel_check(old_thread, 3); - (void) spllo(); + rt_lock_unlock(); + pset_unlock(pset); - call_continuation(continuation, parameter, old_thread->wait_result); - /*NOTREACHED*/ - } + return (new_thread); + } + } - return (TRUE); -} + processor->deadline = UINT64_MAX; + rt_lock_unlock(); -/* - * thread_done: - * - * Perform calculations for thread - * finishing execution on the current processor. - * - * Called at splsched. - */ -void -thread_done( - thread_t old_thread, - thread_t new_thread, - processor_t processor) -{ - if (!(old_thread->state & TH_IDLE)) { - /* - * Compute remainder of current quantum. - */ - if ( first_timeslice(processor) && - processor->quantum_end > processor->last_dispatch ) - old_thread->current_quantum = - (processor->quantum_end - processor->last_dispatch); - else - old_thread->current_quantum = 0; + /* 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); + } - if (old_thread->sched_mode & TH_MODE_REALTIME) { +#if __SMP__ + if (SCHED(steal_thread_enabled)) { /* - * Cancel the deadline if the thread has - * consumed the entire quantum. + * No runnable threads, attempt to steal + * from other processors. Returns with pset lock dropped. */ - if (old_thread->current_quantum == 0) { - old_thread->realtime.deadline = UINT64_MAX; - old_thread->reason |= AST_QUANTUM; + + if ((new_thread = SCHED(steal_thread)(pset)) != THREAD_NULL) { + return (new_thread); } - } - else { + /* - * For non-realtime threads treat a tiny - * remaining quantum as an expired quantum - * but include what's left next time. + * If other threads have appeared, shortcut + * around again. */ - if (old_thread->current_quantum < min_std_quantum) { - old_thread->reason |= AST_QUANTUM; - old_thread->current_quantum += std_quantum; - } + if (!SCHED(processor_queue_empty)(processor) || rt_runq.count > 0) + continue; + + pset_lock(pset); } +#endif + idle: /* - * If we are doing a direct handoff then - * give the remainder of our quantum to - * the next thread. + * Nothing is runnable, so set this processor idle if it + * was running. */ - if ((old_thread->reason & (AST_HANDOFF|AST_QUANTUM)) == AST_HANDOFF) { - new_thread->current_quantum = old_thread->current_quantum; - old_thread->reason |= AST_QUANTUM; - old_thread->current_quantum = 0; + if (processor->state == PROCESSOR_RUNNING) { + processor->state = PROCESSOR_IDLE; + + if (processor->processor_primary == processor) { + re_queue_head(&pset->idle_queue, &processor->processor_queue); + } else { + re_queue_head(&pset->idle_secondary_queue, &processor->processor_queue); + } } - old_thread->last_switch = processor->last_dispatch; +#if __SMP__ + /* Invoked with pset locked, returns with pset unlocked */ + sched_SMT_balance(processor, pset); +#else + pset_unlock(pset); +#endif - old_thread->computation_metered += - (old_thread->last_switch - old_thread->computation_epoch); - } -} +#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); -/* - * thread_begin: - * - * Set up for thread beginning execution on - * the current processor. - * - * Called at splsched. - */ -void -thread_begin( - thread_t thread, - processor_t processor) -{ - if (!(thread->state & TH_IDLE)) { /* - * Give the thread a new quantum - * if none remaining. + * Perform idling activities directly without a + * context switch. Return dispatched thread, + * else check again for a runnable thread. */ - if (thread->current_quantum == 0) - thread_quantum_init(thread); + new_thread = thread_select_idle(thread, processor); +#else /* !CONFIG_SCHED_IDLE_IN_PLACE */ + /* - * Set up quantum timer and timeslice. + * Do a full context switch to idle so that the current + * thread can start running on another processor without + * waiting for the fast-idled processor to wake up. */ - processor->quantum_end = - (processor->last_dispatch + thread->current_quantum); - timer_call_enter1(&processor->quantum_timer, - thread, processor->quantum_end); + new_thread = processor->idle_thread; - processor_timeslice_setup(processor, thread); +#endif /* !CONFIG_SCHED_IDLE_IN_PLACE */ - thread->last_switch = processor->last_dispatch; + } while (new_thread == THREAD_NULL); - thread->computation_epoch = thread->last_switch; - } - else { - timer_call_cancel(&processor->quantum_timer); - processor->timeslice = 1; - } + return (new_thread); } +#if CONFIG_SCHED_IDLE_IN_PLACE /* - * thread_dispatch: + * thread_select_idle: * - * Handle previous thread at context switch. Re-dispatch - * if still running, otherwise update run state and perform - * special actions. + * Idle the processor using the current thread context. * - * Called at splsched. + * Called with thread locked, then dropped and relocked. */ -void -thread_dispatch( - register thread_t thread) +static thread_t +thread_select_idle( + thread_t thread, + processor_t processor) { + thread_t new_thread; + uint64_t arg1, arg2; + int urgency; + + 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); + /* - * If blocked at a continuation, discard - * the stack. + * Switch execution timing to processor idle thread. */ -#ifndef i386 - if (thread->continuation != NULL && thread->kernel_stack) - stack_free(thread); -#endif + processor->last_dispatch = mach_absolute_time(); - if (!(thread->state & TH_IDLE)) { - wake_lock(thread); - thread_lock(thread); +#ifdef CONFIG_MACH_APPROXIMATE_TIME + commpage_update_mach_approximate_time(processor->last_dispatch); +#endif - if (!(thread->state & TH_WAIT)) { - /* - * Still running. - */ - if (thread->reason & AST_QUANTUM) - thread_setrun(thread, SCHED_TAILQ); - else - if (thread->reason & AST_PREEMPT) - thread_setrun(thread, SCHED_HEADQ); - else - thread_setrun(thread, SCHED_PREEMPT | SCHED_TAILQ); + 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; - thread->reason = AST_NONE; + /* + * Cancel the quantum timer while idling. + */ + timer_call_cancel(&processor->quantum_timer); + processor->first_timeslice = FALSE; - thread_unlock(thread); - wake_unlock(thread); - } - else { - boolean_t wake; + (*thread->sched_call)(SCHED_CALL_BLOCK, thread); - /* - * Waiting. - */ - thread->state &= ~TH_RUN; + thread_tell_urgency(THREAD_URGENCY_NONE, 0, 0, 0, NULL); - wake = thread->wake_active; - thread->wake_active = FALSE; + /* + * Enable interrupts and perform idling activities. No + * preemption due to TH_IDLE being set. + */ + spllo(); new_thread = processor_idle(thread, processor); - if (thread->sched_mode & TH_MODE_TIMESHARE) - pset_share_decr(thread->processor_set); - pset_run_decr(thread->processor_set); + /* + * Return at splsched. + */ + (*thread->sched_call)(SCHED_CALL_UNBLOCK, thread); - thread_unlock(thread); - wake_unlock(thread); + thread_lock(thread); - if (thread->options & TH_OPT_CALLOUT) - call_thread_block(); + /* + * If awakened, switch to thread timer and start a new quantum. + * Otherwise skip; we will context switch to another thread or return here. + */ + if (!(thread->state & TH_WAIT)) { + processor->last_dispatch = mach_absolute_time(); + thread_timer_event(processor->last_dispatch, &thread->system_timer); + PROCESSOR_DATA(processor, kernel_timer) = &thread->system_timer; - if (wake) - thread_wakeup((event_t)&thread->wake_active); + thread_quantum_init(thread); + 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; - if (thread->state & TH_TERMINATE) - thread_terminate_enqueue(thread); - } + thread->computation_epoch = processor->last_dispatch; } + + thread->state &= ~TH_IDLE; + + urgency = thread_get_urgency(thread, &arg1, &arg2); + + thread_tell_urgency(urgency, arg1, arg2, 0, new_thread); + + sched_run_incr(thread); + + return (new_thread); } +#endif /* CONFIG_SCHED_IDLE_IN_PLACE */ /* - * thread_block_reason: + * thread_invoke * - * Forces a reschedule, blocking the caller if a wait - * has been asserted. + * Called at splsched with neither thread locked. * - * If a continuation is specified, then thread_invoke will - * attempt to discard the thread's kernel stack. When the - * thread resumes, it will execute the continuation function - * on a new kernel stack. + * 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) */ -counter(mach_counter_t c_thread_block_calls = 0;) - -wait_result_t -thread_block_reason( - thread_continue_t continuation, - void *parameter, +static boolean_t +thread_invoke( + thread_t self, + thread_t thread, ast_t reason) { - register thread_t self = current_thread(); - register processor_t processor; - register thread_t new_thread; - spl_t s; + 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")); + } - counter(++c_thread_block_calls); + thread_continue_t continuation = self->continuation; + void *parameter = self->parameter; + processor_t processor; - s = splsched(); + uint64_t ctime = mach_absolute_time(); - if (!(reason & AST_PREEMPT)) - funnel_release_check(self, 2); +#ifdef CONFIG_MACH_APPROXIMATE_TIME + commpage_update_mach_approximate_time(ctime); +#endif - processor = current_processor(); +#if defined(CONFIG_SCHED_TIMESHARE_CORE) + sched_timeshare_consider_maintenance(ctime); +#endif - /* - * Delay switching to the idle thread under certain conditions. - */ - if (s != FALSE && (self->state & (TH_IDLE|TH_TERMINATE|TH_WAIT)) == TH_WAIT) { - if ( processor->processor_set->processor_count > 1 && - processor->processor_set->runq.count == 0 && - processor->runq.count == 0 ) - processor = delay_idle(processor, self); - } + assert_thread_magic(self); + assert(self == current_thread()); + assert(self->runq == PROCESSOR_NULL); + assert((self->state & (TH_RUN|TH_TERMINATE2)) == TH_RUN); - /* If we're explicitly yielding, force a subsequent quantum */ - if (reason & AST_YIELD) - processor->timeslice = 0; + thread_lock(thread); - /* We're handling all scheduling AST's */ - ast_off(AST_SCHEDULING); + assert_thread_magic(thread); + 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); - self->continuation = continuation; - self->parameter = parameter; + /* Reload precise timing global policy to thread-local policy */ + thread->precise_user_kernel_time = use_precise_user_kernel_time(thread); - thread_lock(self); - new_thread = thread_select(processor); - assert(new_thread && thread_runnable(new_thread)); - thread_unlock(self); - while (!thread_invoke(self, new_thread, reason)) { - thread_lock(self); - new_thread = thread_select(processor); - assert(new_thread && thread_runnable(new_thread)); - thread_unlock(self); - } + /* Update SFI class based on other factors */ + thread->sfi_class = sfi_thread_classify(thread); - funnel_refunnel_check(self, 5); - splx(s); + /* Allow realtime threads to hang onto a stack. */ + if ((self->sched_mode == TH_MODE_REALTIME) && !self->reserved_stack) + self->reserved_stack = self->kernel_stack; - return (self->wait_result); -} + if (continuation != NULL) { + if (!thread->kernel_stack) { + /* + * If we are using a privileged stack, + * check to see whether we can exchange it with + * that of the other thread. + */ + if (self->kernel_stack == self->reserved_stack && !thread->reserved_stack) + goto need_stack; -/* - * thread_block: - * - * Block the current thread if a wait has been asserted. - */ -wait_result_t -thread_block( - thread_continue_t continuation) -{ - return thread_block_reason(continuation, NULL, AST_NONE); -} + /* + * Context switch by performing a stack handoff. + */ + continuation = thread->continuation; + parameter = thread->parameter; -wait_result_t -thread_block_parameter( - thread_continue_t continuation, - void *parameter) -{ - return thread_block_reason(continuation, parameter, AST_NONE); -} + processor = current_processor(); + 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++; + thread->p_switch++; + } + thread->last_processor = processor; + thread->c_switch++; + ast_context(thread); -/* - * thread_run: - * - * Switch directly from the current thread to the - * new thread, handing off our quantum if appropriate. - * - * New thread must be runnable, and not on a run queue. - * - * Called at splsched. - */ -int -thread_run( - thread_t self, - thread_continue_t continuation, - void *parameter, - thread_t new_thread) -{ - ast_t handoff = AST_HANDOFF; + thread_unlock(thread); - funnel_release_check(self, 3); + self->reason = reason; - self->continuation = continuation; - self->parameter = parameter; + processor->last_dispatch = ctime; + self->last_run_time = ctime; + thread_timer_event(ctime, &thread->system_timer); + PROCESSOR_DATA(processor, kernel_timer) = &thread->system_timer; - while (!thread_invoke(self, new_thread, handoff)) { - register processor_t processor = current_processor(); + /* + * 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_STACK_HANDOFF)|DBG_FUNC_NONE, + self->reason, (uintptr_t)thread_tid(thread), self->sched_pri, thread->sched_pri, 0); - thread_lock(self); - new_thread = thread_select(processor); - thread_unlock(self); - handoff = AST_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); + } - funnel_refunnel_check(self, 6); + DTRACE_SCHED2(off__cpu, struct thread *, thread, struct proc *, thread->task->bsd_info); - return (self->wait_result); -} + SCHED_STATS_CSW(processor, self->reason, self->sched_pri, thread->sched_pri); -/* - * thread_continue: - * - * Called at splsched when a thread first receives - * a new stack after a continuation. - */ -void -thread_continue( - register thread_t old_thread) -{ - register thread_t self = current_thread(); - register thread_continue_t continuation; - register void *parameter; - - continuation = self->continuation; - self->continuation = NULL; - parameter = self->parameter; - self->parameter = NULL; + 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); + +#if KPERF + kperf_on_cpu(thread, continuation, NULL); +#endif /* KPERF */ + + thread_dispatch(self, thread); + + thread->continuation = thread->parameter = NULL; + + counter(c_thread_invoke_hits++); + + (void) spllo(); + + assert(continuation); + call_continuation(continuation, parameter, thread->wait_result); + /*NOTREACHED*/ + } + else if (thread == self) { + /* same thread but with continuation */ + ast_context(self); + counter(++c_thread_invoke_same); + + thread_unlock(self); + +#if KPERF + kperf_on_cpu(thread, continuation, NULL); +#endif /* KPERF */ + + 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; + + (void) spllo(); + + call_continuation(continuation, parameter, self->wait_result); + /*NOTREACHED*/ + } + } else { + /* + * Check that the other thread has a stack + */ + if (!thread->kernel_stack) { +need_stack: + if (!stack_alloc_try(thread)) { + counter(c_thread_invoke_misses++); + thread_unlock(thread); + thread_stack_enqueue(thread); + return (FALSE); + } + } else if (thread == self) { + ast_context(self); + counter(++c_thread_invoke_same); + thread_unlock(self); + + 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); + } + } + + /* + * Context switch by full context save. + */ + processor = current_processor(); + 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++; + thread->p_switch++; + } + thread->last_processor = processor; + thread->c_switch++; + ast_context(thread); + + thread_unlock(thread); + + counter(c_thread_invoke_csw++); + + self->reason = reason; + + 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_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)) { + 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); + } + + DTRACE_SCHED2(off__cpu, struct thread *, thread, struct proc *, thread->task->bsd_info); + + SCHED_STATS_CSW(processor, self->reason, self->sched_pri, thread->sched_pri); + + /* + * 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); + +#if KPERF + kperf_on_cpu(self, NULL, __builtin_frame_address(0)); +#endif /* KPERF */ + + /* + * We have been resumed and are set to run. + */ + thread_dispatch(thread, self); + + if (continuation) { + self->continuation = self->parameter = NULL; + + (void) spllo(); + + call_continuation(continuation, parameter, self->wait_result); + /*NOTREACHED*/ + } + + 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_buckets[TH_BUCKET_RUN]; + + /* + * 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, &active_processor->processor_queue); + + 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: + * + * Handle threads at context switch. Re-dispatch other thread + * if still running, otherwise update run state and perform + * 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 +thread_dispatch( + thread_t thread, + thread_t self) +{ + 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 + * the stack. + */ + if (thread->continuation != NULL && thread->kernel_stack != 0) + stack_free(thread); + + 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_buckets[TH_BUCKET_RUN], 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); + + /* + * Apply a priority floor if the thread holds a kernel resource + * Do this before checking starting_pri to avoid overpenalizing + * repeated rwlock blockers. + */ + if (__improbable(thread->rwlock_count != 0)) + lck_rw_set_promotion_locked(thread); + + boolean_t keep_quantum = processor->first_timeslice; + + /* + * Treat a thread which has dropped priority since it got on core + * as having expired its quantum. + */ + if (processor->starting_pri > thread->sched_pri) + keep_quantum = FALSE; + + /* Compute remainder of current quantum. */ + if (keep_quantum && + processor->quantum_end > processor->last_dispatch) + thread->quantum_remaining = (uint32_t)remainder; + else + thread->quantum_remaining = 0; + + if (thread->sched_mode == TH_MODE_REALTIME) { + /* + * Cancel the deadline if the thread has + * consumed the entire quantum. + */ + if (thread->quantum_remaining == 0) { + thread->realtime.deadline = UINT64_MAX; + } + } else { +#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->quantum_remaining < min_std_quantum) { + thread->reason |= AST_QUANTUM; + thread->quantum_remaining += SCHED(initial_quantum_size)(thread); + } +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + } + + /* + * If we are doing a direct handoff then + * take the remainder of the quantum. + */ + if ((thread->reason & (AST_HANDOFF|AST_QUANTUM)) == AST_HANDOFF) { + self->quantum_remaining = thread->quantum_remaining; + thread->reason |= AST_QUANTUM; + 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->state & TH_WAIT)) { + /* + * 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) + thread_setrun(thread, SCHED_HEADQ); + else + thread_setrun(thread, SCHED_PREEMPT | SCHED_TAILQ); + + 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_buckets[TH_BUCKET_RUN], 0); + + if (thread->wake_active) { + thread->wake_active = FALSE; + thread_unlock(thread); + + thread_wakeup(&thread->wake_active); + } else { + thread_unlock(thread); + } + + wake_unlock(thread); + } else { + /* + * Waiting. + */ + boolean_t should_terminate = FALSE; + uint32_t new_run_count; + + /* Only the first call to thread_dispatch + * after explicit termination should add + * the thread to the termination queue + */ + if ((thread->state & (TH_TERMINATE|TH_TERMINATE2)) == TH_TERMINATE) { + should_terminate = TRUE; + thread->state |= TH_TERMINATE2; + } + + thread->state &= ~TH_RUN; + thread->last_made_runnable_time = ~0ULL; + thread->chosen_processor = PROCESSOR_NULL; + + 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 + + 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); + + if (thread->wake_active) { + thread->wake_active = FALSE; + thread_unlock(thread); + + thread_wakeup(&thread->wake_active); + } else { + thread_unlock(thread); + } + + wake_unlock(thread); + + if (should_terminate) + thread_terminate_enqueue(thread); + } + } + } + + /* 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 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 + + assertf(processor->last_dispatch >= self->last_made_runnable_time, "Non-monotonic time? dispatch at 0x%llx, runnable at 0x%llx", 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->quantum_remaining == 0) { + thread_quantum_init(self); + } + + /* + * Set up quantum timer and timeslice. + */ + 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->first_timeslice = TRUE; + } else { + timer_call_cancel(&processor->quantum_timer); + processor->first_timeslice = FALSE; + + thread_tell_urgency(THREAD_URGENCY_NONE, 0, 0, 0, self); + machine_thread_going_on_core(self, THREAD_URGENCY_NONE, 0); + } + + self->computation_epoch = processor->last_dispatch; + self->reason = AST_NONE; + processor->starting_pri = self->sched_pri; + + thread_unlock(self); + +#if defined(CONFIG_SCHED_DEFERRED_AST) + /* + * TODO: Can we state that redispatching our old thread is also + * uninteresting? + */ + if ((((volatile uint32_t)sched_run_buckets[TH_BUCKET_RUN]) == 1) && + !(self->state & TH_IDLE)) { + pset_cancel_deferred_dispatch(processor->processor_set, processor); + } +#endif + +} + +/* + * thread_block_reason: + * + * Forces a reschedule, blocking the caller if a wait + * has been asserted. + * + * If a continuation is specified, then thread_invoke will + * attempt to discard the thread's kernel stack. When the + * thread resumes, it will execute the continuation function + * on a new kernel stack. + */ +counter(mach_counter_t c_thread_block_calls = 0;) + +wait_result_t +thread_block_reason( + thread_continue_t continuation, + void *parameter, + ast_t reason) +{ + thread_t self = current_thread(); + processor_t processor; + thread_t new_thread; + spl_t s; + + counter(++c_thread_block_calls); + + s = splsched(); + + processor = current_processor(); + + /* If we're explicitly yielding, force a subsequent quantum */ + if (reason & AST_YIELD) + processor->first_timeslice = FALSE; + + /* We're handling all scheduling AST's */ + ast_off(AST_SCHEDULING); + +#if PROC_REF_DEBUG + if ((continuation != NULL) && (self->task != kernel_task)) { + if (uthread_get_proc_refcount(self->uthread) != 0) { + panic("thread_block_reason with continuation uthread %p with uu_proc_refcount != 0", self->uthread); + } + } +#endif + + self->continuation = continuation; + self->parameter = parameter; + + 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, reason); + thread_unlock(self); + } while (!thread_invoke(self, new_thread, reason)); + + splx(s); + + return (self->wait_result); +} + +/* + * thread_block: + * + * Block the current thread if a wait has been asserted. + */ +wait_result_t +thread_block( + thread_continue_t continuation) +{ + return thread_block_reason(continuation, NULL, AST_NONE); +} + +wait_result_t +thread_block_parameter( + thread_continue_t continuation, + void *parameter) +{ + return thread_block_reason(continuation, parameter, AST_NONE); +} + +/* + * thread_run: + * + * Switch directly from the current thread to the + * new thread, handing off our quantum if appropriate. + * + * New thread must be runnable, and not on a run queue. + * + * Called at splsched. + */ +int +thread_run( + thread_t self, + thread_continue_t continuation, + void *parameter, + thread_t new_thread) +{ + ast_t handoff = AST_HANDOFF; + + self->continuation = continuation; + self->parameter = parameter; + + while (!thread_invoke(self, new_thread, handoff)) { + processor_t processor = current_processor(); + + thread_lock(self); + new_thread = thread_select(self, processor, AST_NONE); + thread_unlock(self); + handoff = AST_NONE; + } + + return (self->wait_result); +} + +/* + * thread_continue: + * + * Called at splsched when a thread first receives + * a new stack after a continuation. + */ +void +thread_continue( + thread_t thread) +{ + thread_t self = current_thread(); + thread_continue_t continuation; + void *parameter; + + DTRACE_SCHED(on__cpu); + + continuation = self->continuation; + parameter = self->parameter; + +#if KPERF + kperf_on_cpu(self, continuation, NULL); +#endif + + thread_dispatch(thread, self); + + self->continuation = self->parameter = NULL; + + if (thread != THREAD_NULL) + (void)spllo(); + + TLOG(1, "thread_continue: calling call_continuation \n"); + call_continuation(continuation, parameter, self->wait_result); + /*NOTREACHED*/ +} + +void +thread_quantum_init(thread_t thread) +{ + if (thread->sched_mode == TH_MODE_REALTIME) { + thread->quantum_remaining = thread->realtime.computation; + } else { + thread->quantum_remaining = SCHED(initial_quantum_size)(thread); + } +} + +uint32_t +sched_timeshare_initial_quantum_size(thread_t thread) +{ + if ((thread != THREAD_NULL) && thread->th_sched_bucket == TH_BUCKET_SHARE_BG) + return bg_quantum; + else + return std_quantum; +} + +/* + * run_queue_init: + * + * Initialize a run queue before first use. + */ +void +run_queue_init( + run_queue_t rq) +{ + rq->highq = NOPRI; + for (u_int i = 0; i < BITMAP_LEN(NRQS); i++) + rq->bitmap[i] = 0; + rq->urgency = rq->count = 0; + for (int i = 0; i < NRQS; i++) + queue_init(&rq->queues[i]); +} + +/* + * 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]; + + if (options & SCHED_HEADQ) { + thread = qe_dequeue_head(queue, struct thread, runq_links); + } else { + thread = qe_dequeue_tail(queue, struct thread, runq_links); + } + + assert(thread != THREAD_NULL); + assert_thread_magic(thread); + + thread->runq = PROCESSOR_NULL; + SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count); + rq->count--; + if (SCHED(priority_is_urgent)(rq->highq)) { + rq->urgency--; assert(rq->urgency >= 0); + } + if (queue_empty(queue)) { + bitmap_clear(rq->bitmap, rq->highq); + rq->highq = bitmap_first(rq->bitmap, NRQS); + } + + return thread; +} + +/* + * run_queue_enqueue: + * + * Perform a enqueue operation on a run queue. + * + * The run queue must be locked (see thread_run_queue_remove() + * for more info). + */ +boolean_t +run_queue_enqueue( + run_queue_t rq, + thread_t thread, + integer_t options) +{ + queue_t queue = &rq->queues[thread->sched_pri]; + boolean_t result = FALSE; + + assert_thread_magic(thread); + + if (queue_empty(queue)) { + enqueue_tail(queue, &thread->runq_links); + + rq_bitmap_set(rq->bitmap, thread->sched_pri); + if (thread->sched_pri > rq->highq) { + rq->highq = thread->sched_pri; + result = TRUE; + } + } else { + if (options & SCHED_TAILQ) + enqueue_tail(queue, &thread->runq_links); + else + enqueue_head(queue, &thread->runq_links); + } + if (SCHED(priority_is_urgent)(thread->sched_pri)) + rq->urgency++; + SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count); + rq->count++; + + return (result); +} + +/* + * run_queue_remove: + * + * Remove a specific thread from a runqueue. + * + * The run queue must be locked. + */ +void +run_queue_remove( + run_queue_t rq, + thread_t thread) +{ + assert(thread->runq != PROCESSOR_NULL); + assert_thread_magic(thread); + + remqueue(&thread->runq_links); + SCHED_STATS_RUNQ_CHANGE(&rq->runq_stats, rq->count); + rq->count--; + if (SCHED(priority_is_urgent)(thread->sched_pri)) { + rq->urgency--; assert(rq->urgency >= 0); + } + + if (queue_empty(&rq->queues[thread->sched_pri])) { + /* update run queue status */ + bitmap_clear(rq->bitmap, thread->sched_pri); + rq->highq = bitmap_first(rq->bitmap, NRQS); + } + + thread->runq = PROCESSOR_NULL; +} + +/* Assumes RT lock is not held, and acquires splsched/rt_lock itself */ +void +rt_runq_scan(sched_update_scan_context_t scan_context) +{ + spl_t s; + thread_t thread; + + s = splsched(); + rt_lock_lock(); + + qe_foreach_element_safe(thread, &rt_runq.queue, runq_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: + * + * Enqueue a thread for realtime execution. + */ +static boolean_t +realtime_queue_insert(thread_t thread) +{ + queue_t queue = &rt_runq.queue; + uint64_t deadline = thread->realtime.deadline; + boolean_t preempt = FALSE; + + rt_lock_lock(); + + if (queue_empty(queue)) { + enqueue_tail(queue, &thread->runq_links); + preempt = TRUE; + } else { + /* Insert into rt_runq in thread deadline order */ + queue_entry_t iter; + qe_foreach(iter, queue) { + thread_t iter_thread = qe_element(iter, struct thread, runq_links); + assert_thread_magic(iter_thread); + + if (deadline < iter_thread->realtime.deadline) { + if (iter == queue_first(queue)) + preempt = TRUE; + insque(&thread->runq_links, queue_prev(iter)); + break; + } else if (iter == queue_last(queue)) { + enqueue_tail(queue, &thread->runq_links); + break; + } + } + } + + thread->runq = THREAD_ON_RT_RUNQ; + SCHED_STATS_RUNQ_CHANGE(&rt_runq.runq_stats, rt_runq.count); + rt_runq.count++; + + rt_lock_unlock(); + + return (preempt); +} + +/* + * realtime_setrun: + * + * Dispatch a thread for realtime execution. + * + * Thread must be locked. Associated pset must + * be locked, and is returned unlocked. + */ +static void +realtime_setrun( + processor_t processor, + 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; + + /* */ + assert(thread->bound_processor == PROCESSOR_NULL); + + /* + * Dispatch directly onto idle processor. + */ + if ( (thread->bound_processor == processor) + && processor->state == PROCESSOR_IDLE) { + re_queue_tail(&pset->active_queue, &processor->processor_queue); + + 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 (do_signal_idle) { + machine_signal_idle(processor); + } + return; + } + + 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) { + re_queue_tail(&pset->active_queue, &processor->processor_queue); + + 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_TIMESHARE_CORE) + +boolean_t +priority_is_urgent(int priority) +{ + return bitmap_test(sched_preempt_pri, priority) ? TRUE : FALSE; +} + +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + +/* + * processor_setrun: + * + * Dispatch a thread for execution on a + * processor. + * + * Thread must be locked. Associated pset must + * be locked, and is returned unlocked. + */ +static void +processor_setrun( + processor_t processor, + thread_t thread, + integer_t options) +{ + 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; + + /* + * Dispatch directly onto idle processor. + */ + if ( (SCHED(direct_dispatch_to_idle_processors) || + thread->bound_processor == processor) + && processor->state == PROCESSOR_IDLE) { + + re_queue_tail(&pset->active_queue, &processor->processor_queue); + + 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 (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->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; + + SCHED(processor_enqueue)(processor, thread, options); + + if (preempt != AST_NONE) { + if (processor->state == PROCESSOR_IDLE) { + re_queue_tail(&pset->active_queue, &processor->processor_queue); + + 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)) { + ipi_action = eInterruptRunning; + } + } 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 ) { + ipi_action = eInterruptRunning; + } else if ( processor->state == PROCESSOR_IDLE && + processor != current_processor() ) { + re_queue_tail(&pset->active_queue, &processor->processor_queue); + + 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; + } + } + + 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 (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); + } +} + +/* + * choose_next_pset: + * + * Return the next sibling pset containing + * available processors. + * + * Returns the original pset if none other is + * suitable. + */ +static processor_set_t +choose_next_pset( + processor_set_t pset) +{ + processor_set_t nset = pset; + + do { + nset = next_pset(nset); + } while (nset->online_processor_count < 1 && nset != pset); + + return (nset); +} + +/* + * choose_processor: + * + * Choose a processor for the thread, beginning at + * the pset. Accepts an optional processor hint in + * the pset. + * + * Returns a processor, possibly from a different pset. + * + * The thread must be locked. The pset must be locked, + * and the resulting pset is locked on return. + */ +processor_t +choose_processor( + processor_set_t pset, + processor_t processor, + thread_t thread) +{ + processor_set_t nset, cset = pset; + + assert(thread->sched_pri <= BASEPRI_RTQUEUES); + + /* + * Prefer the hinted processor, when appropriate. + */ + + /* Fold last processor hint from secondary processor to its primary */ + if (processor != PROCESSOR_NULL) { + processor = processor->processor_primary; + } + + /* + * 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 = PROCESSOR_NULL; + } 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); + 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. 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, in pset traversal order + */ + qe_foreach_element(processor, &cset->idle_queue, processor_queue) { + if (processor->is_recommended) + return processor; + } - thread_begin(self, self->last_processor); + /* + * Otherwise, enumerate active and idle processors to find candidates + * with lower priority/etc. + */ - if (old_thread != THREAD_NULL) - thread_dispatch(old_thread); + qe_foreach_element(processor, &cset->active_queue, processor_queue) { - funnel_refunnel_check(self, 4); + if (!processor->is_recommended) { + continue; + } - if (old_thread != THREAD_NULL) - (void)spllo(); + integer_t cpri = processor->current_pri; + if (cpri < lowest_priority) { + lowest_priority = cpri; + lp_processor = processor; + } - call_continuation(continuation, parameter, self->wait_result); - /*NOTREACHED*/ -} + if ((cpri >= BASEPRI_RTQUEUES) && (processor->deadline > furthest_deadline)) { + furthest_deadline = processor->deadline; + fd_processor = processor; + } -/* - * Enqueue thread on 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. - * - * Run queue must be locked, see run_queue_remove() - * for more info. - */ -static boolean_t -run_queue_enqueue( - register run_queue_t rq, - register thread_t thread, - integer_t options) -{ - register int whichq = thread->sched_pri; - register queue_t queue = &rq->queues[whichq]; - boolean_t result = FALSE; - - assert(whichq >= MINPRI && whichq <= MAXPRI); + integer_t ccount = SCHED(processor_runq_count)(processor); + if (ccount < lowest_count) { + lowest_count = ccount; + lc_processor = processor; + } + } - assert(thread->runq == RUN_QUEUE_NULL); - if (queue_empty(queue)) { - enqueue_tail(queue, (queue_entry_t)thread); + /* + * 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) { - setbit(MAXPRI - whichq, rq->bitmap); - if (whichq > rq->highq) { - rq->highq = whichq; - result = TRUE; - } - } - else - if (options & SCHED_HEADQ) - enqueue_head(queue, (queue_entry_t)thread); - else - enqueue_tail(queue, (queue_entry_t)thread); + if (!processor->is_recommended) { + continue; + } - thread->runq = rq; - if (thread->sched_mode & TH_MODE_PREEMPT) - rq->urgency++; - rq->count++; + processor_t cprimary = processor->processor_primary; - return (result); -} + /* 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; -/* - * Enqueue a thread for realtime execution, similar - * to above. Handles preemption directly. - */ -static void -realtime_schedule_insert( - register processor_set_t pset, - register thread_t thread) -{ - register run_queue_t rq = &pset->runq; - register int whichq = thread->sched_pri; - register queue_t queue = &rq->queues[whichq]; - uint64_t deadline = thread->realtime.deadline; - boolean_t try_preempt = FALSE; + if (primary_pri < lowest_unpaired_primary_priority) { + lowest_unpaired_primary_priority = primary_pri; + lp_unpaired_primary_processor = cprimary; + lp_unpaired_secondary_processor = processor; + } + } + } - assert(whichq >= BASEPRI_REALTIME && whichq <= MAXPRI); - assert(thread->runq == RUN_QUEUE_NULL); - if (queue_empty(queue)) { - enqueue_tail(queue, (queue_entry_t)thread); + if (thread->sched_pri >= BASEPRI_RTQUEUES) { - setbit(MAXPRI - whichq, rq->bitmap); - if (whichq > rq->highq) - rq->highq = whichq; - try_preempt = TRUE; - } - else { - register thread_t entry = (thread_t)queue_first(queue); + /* + * 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). + */ - while (TRUE) { - if ( queue_end(queue, (queue_entry_t)entry) || - deadline < entry->realtime.deadline ) { - entry = (thread_t)queue_prev((queue_entry_t)entry); - break; + 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, &lp_unpaired_primary_processor->processor_queue); + 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, &lp_processor->processor_queue); + return lp_processor; } + if (thread->realtime.deadline < furthest_deadline) + return fd_processor; - entry = (thread_t)queue_next((queue_entry_t)entry); + /* + * If all primary and secondary CPUs are busy with realtime + * threads with deadlines earlier than us, move on to next + * pset. + */ } + else { - if ((queue_entry_t)entry == queue) - try_preempt = TRUE; - - insque((queue_entry_t)thread, (queue_entry_t)entry); - } + 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, &lp_unpaired_primary_processor->processor_queue); + 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, &lp_processor->processor_queue); + return lp_processor; + } - thread->runq = rq; - assert(thread->sched_mode & TH_MODE_PREEMPT); - rq->count++; rq->urgency++; + /* + * 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 (try_preempt) { - register processor_t processor; + /* + * Move onto the next processor set. + */ + nset = next_pset(cset); - processor = current_processor(); - if ( pset == processor->processor_set && - (thread->sched_pri > processor->current_pri || - deadline < processor->deadline ) ) { - dispatch_counts.realtime_self++; - simple_unlock(&pset->sched_lock); + if (nset != pset) { + pset_unlock(cset); - ast_on(AST_PREEMPT | AST_URGENT); - return; + cset = nset; + pset_lock(cset); } + } while (nset != pset); - if ( pset->processor_count > 1 || - pset != processor->processor_set ) { - processor_t myprocessor, lastprocessor; - queue_entry_t next; - - myprocessor = processor; - processor = thread->last_processor; - if ( processor != myprocessor && - processor != PROCESSOR_NULL && - processor->processor_set == pset && - processor->state == PROCESSOR_RUNNING && - (thread->sched_pri > processor->current_pri || - deadline < processor->deadline ) ) { - dispatch_counts.realtime_last++; - cause_ast_check(processor); - simple_unlock(&pset->sched_lock); - return; - } + /* + * 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 { - lastprocessor = processor; - queue = &pset->active_queue; - processor = (processor_t)queue_first(queue); - while (!queue_end(queue, (queue_entry_t)processor)) { - next = queue_next((queue_entry_t)processor); - - if ( processor != myprocessor && - processor != lastprocessor && - (thread->sched_pri > processor->current_pri || - deadline < processor->deadline ) ) { - if (!queue_end(queue, next)) { - remqueue(queue, (queue_entry_t)processor); - enqueue_tail(queue, (queue_entry_t)processor); - } - dispatch_counts.realtime_other++; - cause_ast_check(processor); - simple_unlock(&pset->sched_lock); - return; - } + /* 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 { + /* + * All processors are executing higher + * priority threads, and the lowest_count + * candidate was not usable + */ + processor = master_processor; + } - processor = (processor_t)next; - } + /* + * Check that the correct processor set is + * returned locked. + */ + if (cset != processor->processor_set) { + pset_unlock(cset); + cset = processor->processor_set; + pset_lock(cset); } - } - simple_unlock(&pset->sched_lock); + /* + * 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 != master_processor && (processor->state == PROCESSOR_SHUTDOWN || processor->state == PROCESSOR_OFF_LINE)) + processor = PROCESSOR_NULL; + + } while (processor == PROCESSOR_NULL); + + return (processor); } /* * thread_setrun: * - * Dispatch thread for execution, directly onto an idle - * processor if possible. Else put on appropriate run - * queue. (local if bound, else processor set) + * Dispatch thread for execution, onto an idle + * processor or run queue, and signal a preemption + * as appropriate. * * Thread must be locked. */ void thread_setrun( - register thread_t new_thread, - integer_t options) + thread_t thread, + integer_t options) { - register processor_t processor; - register processor_set_t pset; - register thread_t thread; - ast_t preempt = (options & SCHED_PREEMPT)? - AST_PREEMPT: AST_NONE; + processor_t processor; + processor_set_t pset; + + assert((thread->state & (TH_RUN|TH_WAIT|TH_UNINT|TH_TERMINATE|TH_TERMINATE2)) == TH_RUN); + assert(thread->runq == PROCESSOR_NULL); - assert(thread_runnable(new_thread)); - /* * Update priority if needed. */ - if (new_thread->sched_stamp != sched_tick) - update_priority(new_thread); + if (SCHED(can_update_priority)(thread)) + SCHED(update_priority)(thread); - /* - * Check for urgent preemption. - */ - if (new_thread->sched_mode & TH_MODE_PREEMPT) - preempt = (AST_PREEMPT | AST_URGENT); + thread->sfi_class = sfi_thread_classify(thread); - assert(new_thread->runq == RUN_QUEUE_NULL); - - if ((processor = new_thread->bound_processor) == PROCESSOR_NULL) { - /* - * First try to dispatch on - * the last processor. - */ - pset = new_thread->processor_set; - processor = new_thread->last_processor; - if ( pset->processor_count > 1 && - processor != PROCESSOR_NULL && - processor->state == PROCESSOR_IDLE ) { - processor_lock(processor); - simple_lock(&pset->sched_lock); - if ( processor->processor_set == pset && - processor->state == PROCESSOR_IDLE ) { - remqueue(&pset->idle_queue, (queue_entry_t)processor); - pset->idle_count--; - processor->next_thread = new_thread; - if (new_thread->sched_pri >= BASEPRI_RTQUEUES) - processor->deadline = new_thread->realtime.deadline; - else - processor->deadline = UINT64_MAX; - processor->state = PROCESSOR_DISPATCHING; - dispatch_counts.idle_pset_last++; - simple_unlock(&pset->sched_lock); - processor_unlock(processor); - if (processor != current_processor()) - machine_signal_idle(processor); - return; - } - processor_unlock(processor); - } - else - simple_lock(&pset->sched_lock); + assert(thread->runq == PROCESSOR_NULL); +#if __SMP__ + if (thread->bound_processor == PROCESSOR_NULL) { /* - * Next pick any idle processor - * in the processor set. + * Unbound case. */ - if (pset->idle_count > 0) { - processor = (processor_t)dequeue_head(&pset->idle_queue); - pset->idle_count--; - processor->next_thread = new_thread; - if (new_thread->sched_pri >= BASEPRI_RTQUEUES) - processor->deadline = new_thread->realtime.deadline; - else - processor->deadline = UINT64_MAX; - processor->state = PROCESSOR_DISPATCHING; - dispatch_counts.idle_pset_any++; - simple_unlock(&pset->sched_lock); - if (processor != current_processor()) - machine_signal_idle(processor); - return; - } + if (thread->affinity_set != AFFINITY_SET_NULL) { + /* + * Use affinity set policy hint. + */ + pset = thread->affinity_set->aset_pset; + pset_lock(pset); - if (new_thread->sched_pri >= BASEPRI_RTQUEUES) - realtime_schedule_insert(pset, new_thread); - else { - if (!run_queue_enqueue(&pset->runq, new_thread, options)) - preempt = AST_NONE; + processor = SCHED(choose_processor)(pset, PROCESSOR_NULL, thread); + 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) { /* - * Update the timesharing quanta. + * Simple (last processor) affinity case. */ - timeshare_quanta_update(pset); - + processor = thread->last_processor; + pset = processor->processor_set; + pset_lock(pset); + processor = SCHED(choose_processor)(pset, processor, thread); + + 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 { /* - * Preempt check. + * No Affinity case: + * + * Utilitize a per task hint to spread threads + * among the available processor sets. */ - if (preempt != AST_NONE) { - /* - * First try the current processor - * if it is a member of the correct - * processor set. - */ - processor = current_processor(); - thread = processor->active_thread; - if ( pset == processor->processor_set && - csw_needed(thread, processor) ) { - dispatch_counts.pset_self++; - simple_unlock(&pset->sched_lock); - - ast_on(preempt); - return; - } + task_t task = thread->task; - /* - * If that failed and we have other - * processors available keep trying. - */ - if ( pset->processor_count > 1 || - pset != processor->processor_set ) { - queue_t queue = &pset->active_queue; - processor_t myprocessor, lastprocessor; - queue_entry_t next; + pset = task->pset_hint; + if (pset == PROCESSOR_SET_NULL) + pset = current_processor()->processor_set; - /* - * Next try the last processor - * dispatched on. - */ - myprocessor = processor; - processor = new_thread->last_processor; - if ( processor != myprocessor && - processor != PROCESSOR_NULL && - processor->processor_set == pset && - processor->state == PROCESSOR_RUNNING && - new_thread->sched_pri > processor->current_pri ) { - dispatch_counts.pset_last++; - cause_ast_check(processor); - simple_unlock(&pset->sched_lock); - return; - } + pset = choose_next_pset(pset); + pset_lock(pset); - /* - * Lastly, pick any other - * available processor. - */ - lastprocessor = processor; - processor = (processor_t)queue_first(queue); - while (!queue_end(queue, (queue_entry_t)processor)) { - next = queue_next((queue_entry_t)processor); - - if ( processor != myprocessor && - processor != lastprocessor && - new_thread->sched_pri > - processor->current_pri ) { - if (!queue_end(queue, next)) { - remqueue(queue, (queue_entry_t)processor); - enqueue_tail(queue, (queue_entry_t)processor); - } - dispatch_counts.pset_other++; - cause_ast_check(processor); - simple_unlock(&pset->sched_lock); - return; - } - - processor = (processor_t)next; - } - } - } + processor = SCHED(choose_processor)(pset, PROCESSOR_NULL, thread); + task->pset_hint = processor->processor_set; - simple_unlock(&pset->sched_lock); + 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 { - /* - * Bound, can only run on bound processor. Have to lock - * processor here because it may not be the current one. - */ - processor_lock(processor); + } else { + /* + * Bound case: + * + * Unconditionally dispatch on the processor. + */ + processor = thread->bound_processor; pset = processor->processor_set; - if (pset != PROCESSOR_SET_NULL) { - simple_lock(&pset->sched_lock); - if (processor->state == PROCESSOR_IDLE) { - remqueue(&pset->idle_queue, (queue_entry_t)processor); - pset->idle_count--; - processor->next_thread = new_thread; - processor->deadline = UINT64_MAX; - processor->state = PROCESSOR_DISPATCHING; - dispatch_counts.idle_bound++; - simple_unlock(&pset->sched_lock); - processor_unlock(processor); - if (processor != current_processor()) - machine_signal_idle(processor); - return; - } - } - - if (!run_queue_enqueue(&processor->runq, new_thread, options)) - preempt = AST_NONE; + pset_lock(pset); - if (preempt != AST_NONE) { - if (processor == current_processor()) { - thread = processor->active_thread; - if (csw_needed(thread, processor)) { - dispatch_counts.bound_self++; - ast_on(preempt); - } - } - else - if ( processor->state == PROCESSOR_RUNNING && - new_thread->sched_pri > processor->current_pri ) { - dispatch_counts.bound_other++; - cause_ast_check(processor); - } - } + 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__ */ - if (pset != PROCESSOR_SET_NULL) - simple_unlock(&pset->sched_lock); + /* + * 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 + processor_setrun(processor, thread, options); +} - processor_unlock(processor); - } +processor_set_t +task_choose_pset( + task_t task) +{ + processor_set_t pset = task->pset_hint; + + if (pset != PROCESSOR_SET_NULL) + pset = choose_next_pset(pset); + + return (pset); } /* - * Check for a possible preemption point in - * the (current) thread. + * Check for a preemption point in + * the current context. * - * Called at splsched. + * Called at splsched with thread locked. */ ast_t csw_check( - thread_t thread, - processor_t processor) + processor_t processor, + ast_t check_reason) { - int current_pri = thread->sched_pri; - ast_t result = AST_NONE; - run_queue_t runq; - - if (first_timeslice(processor)) { - runq = &processor->processor_set->runq; - if (runq->highq >= BASEPRI_RTQUEUES) - return (AST_PREEMPT | AST_URGENT); + processor_set_t pset = processor->processor_set; + ast_t result; - if (runq->highq > current_pri) { - if (runq->urgency > 0) - return (AST_PREEMPT | AST_URGENT); + pset_lock(pset); - result |= AST_PREEMPT; - } + /* 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); - runq = &processor->runq; - if (runq->highq > current_pri) { - if (runq->urgency > 0) - return (AST_PREEMPT | AST_URGENT); + result = csw_check_locked(processor, pset, check_reason); - result |= AST_PREEMPT; - } - } - else { - runq = &processor->processor_set->runq; - if (runq->highq >= current_pri) { - if (runq->urgency > 0) - return (AST_PREEMPT | AST_URGENT); + pset_unlock(pset); - result |= AST_PREEMPT; - } + return result; +} - runq = &processor->runq; - if (runq->highq >= current_pri) { - if (runq->urgency > 0) - return (AST_PREEMPT | AST_URGENT); +/* + * Check for preemption at splsched with + * pset and thread locked + */ +ast_t +csw_check_locked( + processor_t processor, + processor_set_t pset __unused, + ast_t check_reason) +{ + ast_t result; + thread_t thread = processor->active_thread; - result |= AST_PREEMPT; + if (processor->first_timeslice) { + if (rt_runq.count > 0) + return (check_reason | AST_PREEMPT | AST_URGENT); + } + else { + 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 __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 (thread->state & TH_SUSP) - result |= AST_PREEMPT; + return (check_reason | AST_PREEMPT); - return (result); +#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); } /* @@ -2249,321 +3957,329 @@ csw_check( */ void set_sched_pri( - thread_t thread, - int priority) + thread_t thread, + int priority) { - register struct run_queue *rq = run_queue_remove(thread); - - if ( !(thread->sched_mode & TH_MODE_TIMESHARE) && - (priority >= BASEPRI_PREEMPT || - (thread->task_priority < MINPRI_KERNEL && - thread->task_priority >= BASEPRI_BACKGROUND && - priority > thread->task_priority) ) ) - thread->sched_mode |= TH_MODE_PREEMPT; - else - thread->sched_mode &= ~TH_MODE_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; + + 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); + } thread->sched_pri = priority; - if (rq != RUN_QUEUE_NULL) - 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 = csw_check(thread, processor); + 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); - if (preempt != AST_NONE) - ast_on(preempt); - processor->current_pri = priority; + 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); } - else - if ( processor != PROCESSOR_NULL && - processor->active_thread == thread ) - cause_ast_check(processor); } -} - -#if 0 -static void -run_queue_check( - run_queue_t rq, - thread_t thread) -{ - queue_t q; - queue_entry_t qe; - - if (rq != thread->runq) - panic("run_queue_check: thread runq"); - - 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 */ - /* - * run_queue_remove: + * thread_run_queue_remove_for_handoff * - * Remove a thread from its current run queue and - * return the run queue if successful. + * Pull a thread or its (recursive) push target out of the runqueue + * so that it is ready for thread_run() * - * Thread must be locked. + * 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. */ -run_queue_t -run_queue_remove( - thread_t thread) -{ - register run_queue_t rq = thread->runq; - - /* - * If rq is RUN_QUEUE_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 (rq != RUN_QUEUE_NULL) { - processor_set_t pset = thread->processor_set; - processor_t processor = thread->bound_processor; - - /* - * The run queues are locked by the pset scheduling - * lock, except when a processor is off-line the - * local run queue is locked by the processor lock. - */ - if (processor != PROCESSOR_NULL) { - processor_lock(processor); - pset = processor->processor_set; - } +thread_t +thread_run_queue_remove_for_handoff(thread_t thread) { - if (pset != PROCESSOR_SET_NULL) - simple_lock(&pset->sched_lock); + thread_t pulled_thread = THREAD_NULL; - if (rq == thread->runq) { - /* - * Thread is on a run queue and we have a lock on - * that run queue. - */ - remqueue(&rq->queues[0], (queue_entry_t)thread); - rq->count--; - if (thread->sched_mode & TH_MODE_PREEMPT) - rq->urgency--; - assert(rq->urgency >= 0); - - if (queue_empty(rq->queues + thread->sched_pri)) { - /* update run queue status */ - if (thread->sched_pri != IDLEPRI) - clrbit(MAXPRI - thread->sched_pri, rq->bitmap); - rq->highq = MAXPRI - ffsbit(rq->bitmap); - } + thread_lock(thread); - thread->runq = RUN_QUEUE_NULL; - } - else { - /* - * The thread left the run queue before we could - * lock the run queue. - */ - assert(thread->runq == RUN_QUEUE_NULL); - rq = RUN_QUEUE_NULL; - } + /* + * 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. + */ - if (pset != PROCESSOR_SET_NULL) - simple_unlock(&pset->sched_lock); + 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 (processor != PROCESSOR_NULL) - processor_unlock(processor); + if (thread_run_queue_remove(thread)) + pulled_thread = thread; } - return (rq); + thread_unlock(thread); + + return pulled_thread; } /* - * choose_thread: + * thread_run_queue_remove: * - * Remove a thread to execute from the run queues - * and return it. + * 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. * - * Called with pset scheduling lock held. + * 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. */ -static thread_t -choose_thread( - processor_set_t pset, - processor_t processor) +boolean_t +thread_run_queue_remove( + thread_t thread) { - register run_queue_t runq; - register thread_t thread; - register queue_t q; + boolean_t removed = FALSE; + processor_t processor = thread->runq; - runq = &processor->runq; + if ((thread->state & (TH_RUN|TH_WAIT)) == TH_WAIT) { + /* Thread isn't runnable */ + assert(thread->runq == PROCESSOR_NULL); + return FALSE; + } - if (runq->count > 0 && runq->highq >= pset->runq.highq) { - q = runq->queues + runq->highq; + if (processor == PROCESSOR_NULL) { + /* + * 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. + */ - thread = (thread_t)q->next; - ((queue_entry_t)thread)->next->prev = q; - q->next = ((queue_entry_t)thread)->next; - thread->runq = RUN_QUEUE_NULL; - runq->count--; - if (thread->sched_mode & TH_MODE_PREEMPT) - runq->urgency--; - assert(runq->urgency >= 0); - if (queue_empty(q)) { - if (runq->highq != IDLEPRI) - clrbit(MAXPRI - runq->highq, runq->bitmap); - runq->highq = MAXPRI - ffsbit(runq->bitmap); - } + return FALSE; + } + + if (thread->sched_pri < BASEPRI_RTQUEUES) { + return SCHED(processor_queue_remove)(processor, thread); + } + + rt_lock_lock(); - processor->deadline = UINT64_MAX; + if (thread->runq != PROCESSOR_NULL) { + /* + * Thread is on the RT run queue and we have a lock on + * that run queue. + */ - return (thread); - } + assert(thread->runq == THREAD_ON_RT_RUNQ); - runq = &pset->runq; + remqueue(&thread->runq_links); + SCHED_STATS_RUNQ_CHANGE(&rt_runq.runq_stats, rt_runq.count); + rt_runq.count--; - assert(runq->count > 0); - q = runq->queues + runq->highq; + thread->runq = PROCESSOR_NULL; - thread = (thread_t)q->next; - ((queue_entry_t)thread)->next->prev = q; - q->next = ((queue_entry_t)thread)->next; - thread->runq = RUN_QUEUE_NULL; - runq->count--; - if (runq->highq >= BASEPRI_RTQUEUES) - processor->deadline = thread->realtime.deadline; - else - processor->deadline = UINT64_MAX; - if (thread->sched_mode & TH_MODE_PREEMPT) - runq->urgency--; - assert(runq->urgency >= 0); - if (queue_empty(q)) { - if (runq->highq != IDLEPRI) - clrbit(MAXPRI - runq->highq, runq->bitmap); - runq->highq = MAXPRI - ffsbit(runq->bitmap); + removed = TRUE; } - timeshare_quanta_update(pset); + rt_lock_unlock(); - return (thread); + return (removed); } -static processor_t -delay_idle( - processor_t processor, - thread_t self) +/* + * Put the thread back where it goes after a thread_run_queue_remove + * + * Thread must have been removed under the same thread lock hold + * + * thread locked, at splsched + */ +void +thread_run_queue_reinsert(thread_t thread, integer_t options) { - int *gcount, *lcount; - uint64_t abstime, spin, limit; - - lcount = &processor->runq.count; - gcount = &processor->processor_set->runq.count; + assert(thread->runq == PROCESSOR_NULL); - abstime = mach_absolute_time(); - limit = abstime + delay_idle_limit; - spin = abstime + delay_idle_spin; + assert(thread->state & (TH_RUN)); + thread_setrun(thread, options); - timer_event((uint32_t)abstime, &processor->idle_thread->system_timer); - - self->options |= TH_OPT_DELAYIDLE; +} - while ( *gcount == 0 && *lcount == 0 && - (self->state & TH_WAIT) != 0 && - abstime < limit ) { - if (abstime >= spin) { - (void)spllo(); +void +sys_override_cpu_throttle(int flag) +{ + if (flag == CPU_THROTTLE_ENABLE) + cpu_throttle_enabled = 1; + if (flag == CPU_THROTTLE_DISABLE) + cpu_throttle_enabled = 0; +} - (void)splsched(); - processor = current_processor(); - lcount = &processor->runq.count; - gcount = &processor->processor_set->runq.count; +int +thread_get_urgency(thread_t thread, uint64_t *arg1, uint64_t *arg2) +{ + 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 + */ + *arg1 = thread->sched_pri; + *arg2 = thread->base_pri; - abstime = mach_absolute_time(); - spin = abstime + delay_idle_spin; + return (THREAD_URGENCY_BACKGROUND); + } else { + /* For otherwise unclassified threads, report throughput QoS + * parameters + */ + *arg1 = proc_get_effective_thread_policy(thread, TASK_POLICY_THROUGH_QOS); + *arg2 = proc_get_effective_task_policy(thread->task, TASK_POLICY_THROUGH_QOS); - timer_event((uint32_t)abstime, &processor->idle_thread->system_timer); - } - else - abstime = mach_absolute_time(); + return (THREAD_URGENCY_NORMAL); } - - timer_event((uint32_t)abstime, &self->system_timer); - - self->options &= ~TH_OPT_DELAYIDLE; - - return (processor); } -/* - * no_dispatch_count counts number of times processors go non-idle - * without being dispatched. This should be very rare. - */ -int no_dispatch_count = 0; /* - * This is the idle processor thread, which just looks for other threads - * to execute. + * This is the processor idle loop, which just looks for other threads + * to execute. Processor idle threads invoke this without supplying a + * current thread to idle without an asserted wait state. + * + * Returns a the next thread to execute if dispatched directly. */ -void -idle_thread(void) -{ - register processor_t processor; - register thread_t *threadp; - register int *gcount; - register int *lcount; - register thread_t new_thread; - register int state; - register processor_set_t pset; - ast_t *myast = ast_pending(); - processor = current_processor(); +#if 0 +#define IDLE_KERNEL_DEBUG_CONSTANT(...) KERNEL_DEBUG_CONSTANT(__VA_ARGS__) +#else +#define IDLE_KERNEL_DEBUG_CONSTANT(...) do { } while(0) +#endif - threadp = &processor->next_thread; - lcount = &processor->runq.count; - gcount = &processor->processor_set->runq.count; +thread_t +processor_idle( + thread_t thread, + processor_t processor) +{ + processor_set_t pset = processor->processor_set; + thread_t new_thread; + int state; + (void)splsched(); + + 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); + + timer_switch(&PROCESSOR_DATA(processor, system_state), + mach_absolute_time(), &PROCESSOR_DATA(processor, idle_state)); + PROCESSOR_DATA(processor, current_state) = &PROCESSOR_DATA(processor, idle_state); + + 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 - (void)splsched(); /* Turn interruptions off */ + 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); -#ifdef __ppc__ - pmsDown(); /* Step power down. Note: interruptions must be disabled for this call */ -#endif + machine_track_platform_idle(TRUE); - while ( (*threadp == THREAD_NULL) && - (*gcount == 0) && (*lcount == 0) ) { + machine_idle(); - /* check for ASTs while we wait */ - if (*myast &~ (AST_SCHEDULING | AST_BSD)) { - /* no ASTs for us */ - *myast &= AST_NONE; - (void)spllo(); - } - else - 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 (!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; + } } - /* - * This is not a switch statement to avoid the - * bounds checking code in the common case. - */ - pset = processor->processor_set; - simple_lock(&pset->sched_lock); + timer_switch(&PROCESSOR_DATA(processor, idle_state), + mach_absolute_time(), &PROCESSOR_DATA(processor, system_state)); + PROCESSOR_DATA(processor, current_state) = &PROCESSOR_DATA(processor, system_state); -#ifdef __ppc__ - pmsStep(0); /* Step up out of idle power, may start timer for next step */ + 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; @@ -2571,119 +4287,102 @@ idle_thread(void) /* * Commmon case -- cpu dispatched. */ - new_thread = *threadp; - *threadp = (volatile thread_t) THREAD_NULL; + new_thread = processor->next_thread; + processor->next_thread = THREAD_NULL; processor->state = PROCESSOR_RUNNING; - enqueue_tail(&pset->active_queue, (queue_entry_t)processor); - - if ( pset->runq.highq >= BASEPRI_RTQUEUES && - new_thread->sched_pri >= BASEPRI_RTQUEUES ) { - register run_queue_t runq = &pset->runq; - register queue_t q; - - q = runq->queues + runq->highq; - if (((thread_t)q->next)->realtime.deadline < - processor->deadline) { - thread_t thread = new_thread; - - new_thread = (thread_t)q->next; - ((queue_entry_t)new_thread)->next->prev = q; - q->next = ((queue_entry_t)new_thread)->next; - new_thread->runq = RUN_QUEUE_NULL; - processor->deadline = new_thread->realtime.deadline; - assert(new_thread->sched_mode & TH_MODE_PREEMPT); - runq->count--; runq->urgency--; - if (queue_empty(q)) { - if (runq->highq != IDLEPRI) - clrbit(MAXPRI - runq->highq, runq->bitmap); - runq->highq = MAXPRI - ffsbit(runq->bitmap); - } - dispatch_counts.missed_realtime++; - simple_unlock(&pset->sched_lock); - thread_lock(thread); - thread_setrun(thread, SCHED_HEADQ); - thread_unlock(thread); + 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; - counter(c_idle_thread_handoff++); - thread_run(processor->idle_thread, (thread_continue_t)idle_thread, NULL, new_thread); - /*NOTREACHED*/ - } - simple_unlock(&pset->sched_lock); + pset_unlock(pset); - counter(c_idle_thread_handoff++); - thread_run(processor->idle_thread, (thread_continue_t)idle_thread, NULL, new_thread); - /*NOTREACHED*/ + thread_lock(new_thread); + KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_REDISPATCH), (uintptr_t)thread_tid(new_thread), new_thread->sched_pri, rt_runq.count, 0, 0); + thread_setrun(new_thread, SCHED_HEADQ); + thread_unlock(new_thread); + + 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); } - if ( processor->runq.highq > new_thread->sched_pri || - pset->runq.highq > new_thread->sched_pri ) { - thread_t thread = new_thread; + pset_unlock(pset); - new_thread = choose_thread(pset, processor); - dispatch_counts.missed_other++; - simple_unlock(&pset->sched_lock); + 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); - thread_lock(thread); - thread_setrun(thread, SCHED_HEADQ); - thread_unlock(thread); + return (new_thread); - counter(c_idle_thread_handoff++); - thread_run(processor->idle_thread, (thread_continue_t)idle_thread, NULL, new_thread); - /* NOTREACHED */ - } - else { - simple_unlock(&pset->sched_lock); + } else if (state == PROCESSOR_IDLE) { + re_queue_tail(&pset->active_queue, &processor->processor_queue); - counter(c_idle_thread_handoff++); - thread_run(processor->idle_thread, (thread_continue_t)idle_thread, NULL, new_thread); - /* NOTREACHED */ - } - } - else - if (state == PROCESSOR_IDLE) { - /* - * Processor was not dispatched (Rare). - * Set it running again and force a - * reschedule. - */ - no_dispatch_count++; - pset->idle_count--; - remqueue(&pset->idle_queue, (queue_entry_t)processor); processor->state = PROCESSOR_RUNNING; - enqueue_tail(&pset->active_queue, (queue_entry_t)processor); - simple_unlock(&pset->sched_lock); + processor->current_pri = IDLEPRI; + processor->current_thmode = TH_MODE_FIXED; + processor->current_sfi_class = SFI_CLASS_KERNEL; + processor->deadline = UINT64_MAX; - counter(c_idle_thread_block++); - thread_block((thread_continue_t)idle_thread); - /* NOTREACHED */ - } - else - if (state == PROCESSOR_SHUTDOWN) { + } else if (state == PROCESSOR_SHUTDOWN) { /* * Going off-line. Force a * reschedule. */ - if ((new_thread = (thread_t)*threadp) != THREAD_NULL) { - *threadp = (volatile thread_t) THREAD_NULL; + 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; - simple_unlock(&pset->sched_lock); + + pset_unlock(pset); thread_lock(new_thread); thread_setrun(new_thread, SCHED_HEADQ); thread_unlock(new_thread); - } - else - simple_unlock(&pset->sched_lock); - counter(c_idle_thread_block++); - thread_block((thread_continue_t)idle_thread); - /* NOTREACHED */ + 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); + } } - simple_unlock(&pset->sched_lock); + pset_unlock(pset); + + 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); +} + +/* + * Each processor has a dedicated thread which + * executes the idle loop when there is no suitable + * previous context. + */ +void +idle_thread(void) +{ + processor_t processor = current_processor(); + thread_t new_thread; + + new_thread = processor_idle(THREAD_NULL, processor); + if (new_thread != THREAD_NULL) { + thread_run(processor->idle_thread, (thread_continue_t)idle_thread, NULL, new_thread); + /*NOTREACHED*/ + } - panic("idle_thread: state %d\n", processor->state); + thread_block((thread_continue_t)idle_thread); /*NOTREACHED*/ } @@ -2703,8 +4402,9 @@ 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); @@ -2713,8 +4413,6 @@ idle_thread_create( return (KERN_SUCCESS); } -static uint64_t sched_tick_deadline; - /* * sched_startup: * @@ -2728,105 +4426,181 @@ sched_startup(void) kern_return_t result; thread_t thread; - result = kernel_thread_start_priority((thread_continue_t)sched_tick_thread, NULL, MAXPRI_KERNEL, &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); if (result != KERN_SUCCESS) panic("sched_startup"); thread_deallocate(thread); + assert_thread_magic(thread); + /* - * Yield to the sched_tick_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_daemon_init(); - - thread_call_initialize(); + thread_block(THREAD_CONTINUE_NULL); } +#if defined(CONFIG_SCHED_TIMESHARE_CORE) + +static volatile uint64_t sched_maintenance_deadline; +static uint64_t sched_tick_last_abstime; +static uint64_t sched_tick_delta; +uint64_t sched_tick_max_delta; /* - * sched_tick_thread: + * sched_init_thread: * * Perform periodic bookkeeping functions about ten * times per second. */ -static void -sched_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); + } + + KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_MAINTENANCE)|DBG_FUNC_START, + sched_tick_delta, late_time, 0, 0, 0); - sched_tick++; + /* 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. + * may need to be updated, and find the earliest runnable thread on the runqueue + * to report its latency. + */ + SCHED(thread_update_scan)(&scan_context); + + rt_runq_scan(&scan_context); + + uint64_t ctime = mach_absolute_time(); + + uint64_t bg_max_latency = (ctime > scan_context.earliest_bg_make_runnable_time) ? + ctime - scan_context.earliest_bg_make_runnable_time : 0; + + uint64_t default_max_latency = (ctime > scan_context.earliest_normal_make_runnable_time) ? + ctime - scan_context.earliest_normal_make_runnable_time : 0; + + uint64_t realtime_max_latency = (ctime > scan_context.earliest_rt_make_runnable_time) ? + ctime - scan_context.earliest_rt_make_runnable_time : 0; + + machine_max_runnable_latency(bg_max_latency, default_max_latency, realtime_max_latency); + + /* + * Check to see if the special sched VM group needs attention. */ - thread_update_scan(); + sched_vm_group_maintenance(); + - clock_deadline_for_periodic_event(sched_tick_interval, abstime, - &sched_tick_deadline); + KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_MAINTENANCE) | DBG_FUNC_END, + sched_pri_shifts[TH_BUCKET_SHARE_FG], sched_pri_shifts[TH_BUCKET_SHARE_BG], + sched_pri_shifts[TH_BUCKET_SHARE_UT], 0, 0); - assert_wait_deadline((event_t)sched_tick_thread, THREAD_UNINT, sched_tick_deadline); - thread_block((thread_continue_t)sched_tick_continue); + 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; - uint64_t abstime; - int i, tries = 7; +void +sched_timeshare_consider_maintenance(uint64_t ctime) { + uint64_t ndeadline, deadline = sched_maintenance_deadline; - accum = hi = low = 0; - for (i = 0; i < tries; ++i) { - abstime = mach_absolute_time(); - thread_block(THREAD_CONTINUE_NULL); + if (__improbable(ctime >= deadline)) { + if (__improbable(current_thread() == sched_maintenance_thread)) + return; + OSMemoryBarrier(); - new = mach_absolute_time() - abstime; + 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++; } } - - return ((accum - hi - low) / (2 * (tries - 2))); } +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + void -sched_tick_thread(void) +sched_init_thread(void (*continuation)(void)) { - sched_cswtime = time_cswitch(); + thread_block(THREAD_CONTINUE_NULL); + + thread_t thread = current_thread(); + + thread_set_thread_name(thread, "sched_maintenance_thread"); - sched_tick_deadline = mach_absolute_time(); + sched_maintenance_thread = thread; + + continuation(); - sched_tick_continue(); /*NOTREACHED*/ } +#if defined(CONFIG_SCHED_TIMESHARE_CORE) + /* * thread_update_scan / runq_scan: * @@ -2845,117 +4619,205 @@ sched_tick_thread(void) #define THREAD_UPDATE_SIZE 128 -static thread_t thread_update_array[THREAD_UPDATE_SIZE]; -static int thread_update_count = 0; +static thread_t thread_update_array[THREAD_UPDATE_SIZE]; +static uint32_t 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) +{ + assert(thread_update_count <= THREAD_UPDATE_SIZE); + + for (uint32_t i = 0 ; i < thread_update_count ; i++) { + thread_t thread = thread_update_array[i]; + assert_thread_magic(thread); + thread_update_array[i] = THREAD_NULL; + + spl_t s = splsched(); + thread_lock(thread); + if (!(thread->state & (TH_WAIT)) && thread->sched_stamp != sched_tick) { + SCHED(update_priority)(thread); + } + thread_unlock(thread); + splx(s); + + thread_deallocate(thread); + } + + thread_update_count = 0; +} /* * Scan a runq for candidate threads. * * Returns TRUE if retry is needed. */ -static boolean_t +boolean_t runq_scan( - run_queue_t runq) -{ - register int count; - register queue_t q; - register thread_t thread; - - if ((count = runq->count) > 0) { - q = runq->queues + runq->highq; - while (count > 0) { - 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) - return (TRUE); - - thread_update_array[thread_update_count++] = thread; - thread_reference_internal(thread); - } + run_queue_t runq, + sched_update_scan_context_t scan_context) +{ + int count = runq->count; + int queue_index; + + assert(count >= 0); + + if (count == 0) + return FALSE; + + for (queue_index = bitmap_first(runq->bitmap, NRQS); + queue_index >= 0; + queue_index = bitmap_next(runq->bitmap, queue_index)) { - count--; + thread_t thread; + queue_t queue = &runq->queues[queue_index]; + + qe_foreach_element(thread, queue, runq_links) { + assert(count > 0); + assert_thread_magic(thread); + + if (thread->sched_stamp != sched_tick && + thread->sched_mode == TH_MODE_TIMESHARE) { + if (thread_update_add_thread(thread) == FALSE) + return TRUE; } - q--; + 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--; } } - return (FALSE); + return FALSE; } -static void -thread_update_scan(void) +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + +boolean_t +thread_eager_preemption(thread_t thread) { - register boolean_t restart_needed; - register processor_set_t pset = &default_pset; - register processor_t processor; - register thread_t thread; - spl_t s; + return ((thread->sched_flags & TH_SFLAG_EAGERPREEMPT) != 0); +} - do { - s = splsched(); - simple_lock(&pset->sched_lock); - restart_needed = runq_scan(&pset->runq); - simple_unlock(&pset->sched_lock); - - if (!restart_needed) { - simple_lock(&pset->sched_lock); - processor = (processor_t)queue_first(&pset->processors); - while (!queue_end(&pset->processors, (queue_entry_t)processor)) { - if ((restart_needed = runq_scan(&processor->runq)) != 0) - break; +void +thread_set_eager_preempt(thread_t thread) +{ + spl_t x; + processor_t p; + ast_t ast = AST_NONE; - thread = processor->idle_thread; - if (thread->sched_stamp != sched_tick) { - if (thread_update_count == THREAD_UPDATE_SIZE) { - restart_needed = TRUE; - break; - } + x = splsched(); + p = current_processor(); - thread_update_array[thread_update_count++] = thread; - thread_reference_internal(thread); - } + thread_lock(thread); + thread->sched_flags |= TH_SFLAG_EAGERPREEMPT; - processor = (processor_t)queue_next(&processor->processors); - } - simple_unlock(&pset->sched_lock); + if (thread == current_thread()) { + + ast = csw_check(p, AST_NONE); + thread_unlock(thread); + if (ast != AST_NONE) { + (void) thread_block_reason(THREAD_CONTINUE_NULL, NULL, ast); } - splx(s); + } else { + p = thread->last_processor; - /* - * 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; + if (p != PROCESSOR_NULL && p->state == PROCESSOR_RUNNING && + p->active_thread == thread) { + cause_ast_check(p); + } + + thread_unlock(thread); + } - s = splsched(); - thread_lock(thread); - if ( !(thread->state & (TH_WAIT|TH_SUSP)) && - thread->sched_stamp != sched_tick ) - update_priority(thread); - thread_unlock(thread); - splx(s); + splx(x); +} + +void +thread_clear_eager_preempt(thread_t thread) +{ + spl_t x; + + x = splsched(); + thread_lock(thread); + + thread->sched_flags &= ~TH_SFLAG_EAGERPREEMPT; + + thread_unlock(thread); + splx(x); +} + +/* + * Scheduling statistics + */ +void +sched_stats_handle_csw(processor_t processor, int reasons, int selfpri, int otherpri) +{ + struct processor_sched_statistics *stats; + boolean_t to_realtime = FALSE; + + stats = &processor->processor_data.sched_stats; + stats->csw_count++; - thread_deallocate(thread); - } - } while (restart_needed); + if (otherpri >= BASEPRI_REALTIME) { + stats->rt_sched_count++; + to_realtime = TRUE; + } + + if ((reasons & AST_PREEMPT) != 0) { + stats->preempt_count++; + + if (selfpri >= BASEPRI_REALTIME) { + stats->preempted_rt_count++; + } + + if (to_realtime) { + stats->preempted_by_rt_count++; + } + + } } - + +void +sched_stats_handle_runq_change(struct runq_stats *stats, int old_count) +{ + uint64_t timestamp = mach_absolute_time(); + + stats->count_sum += (timestamp - stats->last_change_timestamp) * old_count; + stats->last_change_timestamp = timestamp; +} + /* - * Just in case someone doesn't use the macro + * For calls from assembly code */ -#undef thread_wakeup +#undef thread_wakeup void thread_wakeup( - event_t x); + event_t x); void thread_wakeup( - event_t x) + event_t x) { - thread_wakeup_with_result(x, THREAD_AWAKENED); + thread_wakeup_with_result(x, THREAD_AWAKENED); } boolean_t @@ -2964,43 +4826,52 @@ 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 -#define printf kdbprintf -void db_sched(void); -void -db_sched(void) -{ - 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 no_dispatch %d\n", - c_idle_thread_handoff, - c_idle_thread_block, no_dispatch_count); - iprintf("Sched thread blocks: %d\n", c_sched_thread_block); -#endif /* MACH_COUNTERS */ - db_indent -= 2; -} - -#include -void db_show_thread_log(void); -void -db_show_thread_log(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) { + int urgency; + uint64_t urgency_param1, urgency_param2; + spl_t s; + + if (work_interval_id == 0) { + return (KERN_INVALID_ARGUMENT); + } + + 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 */