X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/43866e378188c25dd1e2208016ab3cbeb086ae6c..d9a64523371fa019c4575bb400cbbc3a50ac9903:/osfmk/kern/sched_prim.c diff --git a/osfmk/kern/sched_prim.c b/osfmk/kern/sched_prim.c index 2e7a7fc5d..751b57417 100644 --- a/osfmk/kern/sched_prim.c +++ b/osfmk/kern/sched_prim.c @@ -1,16 +1,19 @@ /* - * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. + * Copyright (c) 2000-2016 Apple Inc. All rights reserved. * - * @APPLE_LICENSE_HEADER_START@ - * - * Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved. + * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in - * compliance with the License. Please obtain a copy of the License at - * http://www.opensource.apple.com/apsl/ and read it before using this - * file. + * compliance with the License. The rights granted to you under the License + * may not be used to create, or enable the creation or redistribution of, + * unlawful or unlicensed copies of an Apple operating system, or to + * circumvent, violate, or enable the circumvention or violation of, any + * terms of an Apple operating system software license agreement. + * + * Please obtain a copy of the License at + * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER @@ -20,7 +23,7 @@ * Please see the License for the specific language governing rights and * limitations under the License. * - * @APPLE_LICENSE_HEADER_END@ + * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ /* * @OSF_FREE_COPYRIGHT@ @@ -62,52 +65,87 @@ */ #include -#include -#include -#include -#include -#include -#include +#include #include +#include +#include +#include + #include #include -#include +#include +#include +#include + +#include + +#include +#include #include #include #include #include -#include -#include +#include +#include #include #include #include +#if MONOTONIC +#include +#endif /* MONOTONIC */ #include #include #include #include +#include #include #include #include -#include +#include +#include +#include +#include +#include + #include #include #include -#include -#include -#include /*** ??? fix so this can be removed ***/ +#include + +#include +#include +#include + #include +#include +#include +#include +#include +#include +#include + +int rt_runq_count(processor_set_t pset) +{ + return atomic_load_explicit(&SCHED(rt_runq)(pset)->count, memory_order_relaxed); +} -#if TASK_SWAPPER -#include -extern int task_swap_on; -#endif /* TASK_SWAPPER */ +void rt_runq_count_incr(processor_set_t pset) +{ + atomic_fetch_add_explicit(&SCHED(rt_runq)(pset)->count, 1, memory_order_relaxed); +} -extern int hz; +void rt_runq_count_decr(processor_set_t pset) +{ + atomic_fetch_sub_explicit(&SCHED(rt_runq)(pset)->count, 1, memory_order_relaxed); +} #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; @@ -117,117 +155,260 @@ 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_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; + +#if defined(CONFIG_SCHED_TIMESHARE_CORE) + +unsigned sched_tick; +uint32_t sched_tick_interval; + +/* Timeshare load calculation interval (15ms) */ +uint32_t sched_load_compute_interval_us = 15000; +uint64_t sched_load_compute_interval_abs; +static _Atomic uint64_t sched_load_compute_deadline; + +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; -unsigned sched_tick; +/* 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 */ -#if SIMPLE_CLOCK -int sched_usec; -#endif /* SIMPLE_CLOCK */ +uint64_t timer_deadline_tracking_bin_1; +uint64_t timer_deadline_tracking_bin_2; + +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + +thread_t sched_maintenance_thread; + +#if __arm__ || __arm64__ +/* interrupts disabled lock to guard recommended cores state */ +decl_simple_lock_data(static,sched_recommended_cores_lock); +static void sched_recommended_cores_maintenance(void); +static void sched_update_recommended_cores(uint32_t recommended_cores); + +uint64_t perfcontrol_failsafe_starvation_threshold; +extern char *proc_name_address(struct proc *p); + +#endif /* __arm__ || __arm64__ */ + +uint64_t sched_one_second_interval; /* Forwards */ -void wait_queues_init(void); -thread_t choose_pset_thread( - processor_t myprocessor, - processor_set_t pset); +#if defined(CONFIG_SCHED_TIMESHARE_CORE) -thread_t choose_thread( - processor_t myprocessor); +static void load_shift_init(void); +static void preempt_pri_init(void); -boolean_t run_queue_enqueue( - run_queue_t runq, - thread_t thread, - boolean_t tail); +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ -void do_thread_scan(void); +#if CONFIG_SCHED_IDLE_IN_PLACE +static thread_t thread_select_idle( + thread_t thread, + processor_t processor); +#endif -#if DEBUG -void dump_run_queues( - run_queue_t rq); -void dump_run_queue_struct( - run_queue_t rq); -void dump_processor( - processor_t p); -void dump_processor_set( - processor_set_t ps); +thread_t processor_idle( + thread_t thread, + processor_t processor); -void checkrq( - run_queue_t rq, - char *msg); +ast_t +csw_check_locked( processor_t processor, + processor_set_t pset, + ast_t check_reason); -void thread_check( - thread_t thread, - run_queue_t runq); +static void processor_setrun( + processor_t processor, + thread_t thread, + integer_t options); -static -boolean_t thread_runnable( - thread_t thread); +static void +sched_realtime_timebase_init(void); -#endif /*DEBUG*/ +static void +sched_timer_deadline_tracking_init(void); +#if DEBUG +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 -/* - * State machine - * - * states are combinations of: - * R running - * W waiting (or on wait queue) - * N non-interruptible - * O swapped out - * I being swapped in - * - * init action - * assert_wait thread_block clear_wait swapout swapin - * - * R RW, RWN R; setrun - - - * RN RWN RN; setrun - - - * - * RW W R - - * RWN WN RN - - * - * W R; setrun WO - * WN RN; setrun - - * - * RO - - R - * - */ +static processor_t +thread_bind_internal( + thread_t thread, + processor_t processor); + +static void +sched_vm_group_maintenance(void); + +#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. + * 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. * - * Scheduling operations may also occur at interrupt level; therefore, - * interrupts below splsched() must be prevented when holding - * thread or hash bucket locks. - * - * 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]; + +uint32_t sched_debug_flags = SCHED_DEBUG_FLAG_CHOOSE_PROCESSOR_TRACEPOINTS; + +/* Global flag which indicates whether Background Stepper Context is enabled */ +static int cpu_throttle_enabled = 1; + +#if DEBUG -#define NUMQUEUES 59 +/* Since using the indirect function dispatch table has a negative impact on + * context switch performance, only allow DEBUG kernels to use that mechanism. + */ +static void +sched_init_override(void) +{ + char sched_arg[SCHED_STRING_MAX_LENGTH] = { '\0' }; -struct wait_queue wait_queues[NUMQUEUES]; + /* Check for runtime selection of the scheduler algorithm */ + if (!PE_parse_boot_argn("sched", sched_arg, sizeof (sched_arg))) { + sched_arg[0] = '\0'; + } + 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_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_dualq_dispatch; +#elif defined(CONFIG_SCHED_TRADITIONAL) + sched_current_dispatch = &sched_traditional_with_pset_runqueue_dispatch; +#else +#error No default scheduler implementation +#endif + kprintf("Scheduler: Default of %s\n", SCHED(sched_name)); + } +} -#define wait_hash(event) \ - ((((int)(event) < 0)? ~(int)(event): (int)(event)) % NUMQUEUES) +#endif /* DEBUG */ void sched_init(void) +{ +#if DEBUG + sched_init_override(); +#else /* DEBUG */ + kprintf("Scheduler: Default of %s\n", SCHED(sched_name)); +#endif /* DEBUG */ + + 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 (PE_parse_boot_argn("sched_debug", &sched_debug_flags, sizeof(sched_debug_flags))) { + kprintf("Scheduler: Debug flags 0x%08x\n", sched_debug_flags); + } + strlcpy(sched_string, SCHED(sched_name), sizeof(sched_string)); + + cpu_quiescent_counter_init(); + + SCHED(init)(); + SCHED(rt_init)(&pset0); + sched_timer_deadline_tracking_init(); + + SCHED(pset_init)(&pset0); + SCHED(processor_init)(master_processor); +} + +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 @@ -239,277 +420,512 @@ sched_init(void) printf("standard timeslicing quantum is %d us\n", std_quantum_us); - wait_queues_init(); - pset_sys_bootstrap(); /* initialize processor mgmt. */ - processor_action(); + if (default_bg_preemption_rate < 1) + default_bg_preemption_rate = DEFAULT_BG_PREEMPTION_RATE; + bg_quantum_us = (1000 * 1000) / default_bg_preemption_rate; + + printf("standard background quantum is %d us\n", bg_quantum_us); + + load_shift_init(); + preempt_pri_init(); sched_tick = 0; -#if SIMPLE_CLOCK - sched_usec = 0; -#endif /* SIMPLE_CLOCK */ - ast_init(); } void -wait_queues_init(void) +sched_timeshare_timebase_init(void) { - register int i; + uint64_t abstime; + uint32_t shift; + + /* standard timeslicing quantum */ + clock_interval_to_absolutetime_interval( + std_quantum_us, NSEC_PER_USEC, &abstime); + assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); + 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 = (uint32_t)abstime; + + /* quantum for background tasks */ + clock_interval_to_absolutetime_interval( + bg_quantum_us, NSEC_PER_USEC, &abstime); + assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); + bg_quantum = (uint32_t)abstime; + + /* scheduler tick interval */ + clock_interval_to_absolutetime_interval(USEC_PER_SEC >> SCHED_TICK_SHIFT, + NSEC_PER_USEC, &abstime); + assert((abstime >> 32) == 0 && (uint32_t)abstime != 0); + sched_tick_interval = (uint32_t)abstime; + + /* timeshare load calculation interval & deadline initialization */ + clock_interval_to_absolutetime_interval(sched_load_compute_interval_us, NSEC_PER_USEC, &sched_load_compute_interval_abs); + sched_load_compute_deadline = sched_load_compute_interval_abs; + + /* + * Compute conversion factor from usage to + * timesharing priorities with 5/8 ** n aging. + */ + abstime = (abstime * 5) / 3; + for (shift = 0; abstime > BASEPRI_DEFAULT; ++shift) + abstime >>= 1; + sched_fixed_shift = shift; - for (i = 0; i < NUMQUEUES; i++) { - wait_queue_init(&wait_queues[i], SYNC_POLICY_FIFO); - } + for (uint32_t i = 0 ; i < TH_BUCKET_MAX ; i++) + sched_pri_shifts[i] = INT8_MAX; + + 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; + +#if __arm__ || __arm64__ + perfcontrol_failsafe_starvation_threshold = (2 * sched_tick_interval); +#endif /* __arm__ || __arm64__ */ } -/* - * Thread wait timer expiration. - */ +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + void -thread_timer_expire( - timer_call_param_t p0, - timer_call_param_t p1) +pset_rt_init(processor_set_t pset) { - thread_t thread = p0; - spl_t s; + rt_lock_init(pset); - s = splsched(); - wake_lock(thread); - if (--thread->wait_timer_active == 1) { - if (thread->wait_timer_is_set) { - thread->wait_timer_is_set = FALSE; - thread_lock(thread); - if (thread->active) - clear_wait_internal(thread, THREAD_TIMED_OUT); - thread_unlock(thread); - } - } - else - if (thread->wait_timer_active == 0) - thread_wakeup_one(&thread->wait_timer_active); - wake_unlock(thread); - splx(s); + pset->rt_runq.count = 0; + queue_init(&pset->rt_runq.queue); + memset(&pset->rt_runq.runq_stats, 0, sizeof pset->rt_runq.runq_stats); } -/* - * 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) +rt_queue_t +sched_rtglobal_runq(processor_set_t pset) { - thread_t thread = current_thread(); - uint64_t deadline; - spl_t s; + (void)pset; - s = splsched(); - wake_lock(thread); - thread_lock(thread); - if ((thread->state & TH_WAIT) != 0) { - clock_interval_to_deadline(interval, scale_factor, &deadline); - timer_call_enter(&thread->wait_timer, deadline); - assert(!thread->wait_timer_is_set); - thread->wait_timer_active++; - thread->wait_timer_is_set = TRUE; - } - thread_unlock(thread); - wake_unlock(thread); - splx(s); + return &pset0.rt_runq; } void -thread_set_timer_deadline( - uint64_t deadline) +sched_rtglobal_init(processor_set_t pset) { - thread_t thread = current_thread(); - spl_t s; - - s = splsched(); - wake_lock(thread); - thread_lock(thread); - if ((thread->state & TH_WAIT) != 0) { - timer_call_enter(&thread->wait_timer, deadline); - assert(!thread->wait_timer_is_set); - thread->wait_timer_active++; - thread->wait_timer_is_set = TRUE; + if (pset == &pset0) { + return pset_rt_init(pset); } - thread_unlock(thread); - wake_unlock(thread); - splx(s); + + /* Only pset0 rt_runq is used, so make it easy to detect + * buggy accesses to others. + */ + memset(&pset->rt_runq, 0xfd, sizeof pset->rt_runq); } void -thread_cancel_timer(void) +sched_rtglobal_queue_shutdown(processor_t processor) { - thread_t thread = current_thread(); - spl_t s; - - s = splsched(); - wake_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; - } - wake_unlock(thread); - splx(s); + (void)processor; } -/* - * Set up thread timeout element when thread is created. - */ -void -thread_timer_setup( - thread_t thread) +static void +sched_realtime_timebase_init(void) { - extern void thread_depress_expire( - timer_call_param_t p0, - timer_call_param_t p1); + uint64_t abstime; - timer_call_setup(&thread->wait_timer, thread_timer_expire, thread); - thread->wait_timer_is_set = FALSE; - thread->wait_timer_active = 1; + /* 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; - timer_call_setup(&thread->depress_timer, thread_depress_expire, thread); - thread->depress_timer_active = 1; + /* 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; - thread->ref_count++; } void -thread_timer_terminate(void) +sched_check_spill(processor_set_t pset, thread_t thread) { - thread_t thread = current_thread(); - wait_result_t res; - spl_t s; + (void)pset; + (void)thread; - s = splsched(); - wake_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; - } + return; +} - thread->wait_timer_active--; +bool +sched_thread_should_yield(processor_t processor, thread_t thread) +{ + (void)thread; - while (thread->wait_timer_active > 0) { - res = assert_wait((event_t)&thread->wait_timer_active, THREAD_UNINT); - assert(res == THREAD_WAITING); - wake_unlock(thread); - splx(s); + return (!SCHED(processor_queue_empty)(processor) || rt_runq_count(processor->processor_set) > 0); +} - res = thread_block(THREAD_CONTINUE_NULL); - assert(res == THREAD_AWAKENED); +#if defined(CONFIG_SCHED_TIMESHARE_CORE) - s = splsched(); - wake_lock(thread); +/* + * Set up values for timeshare + * loading factors. + */ +static void +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); } - thread->depress_timer_active--; + 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); + } - while (thread->depress_timer_active > 0) { - res = assert_wait((event_t)&thread->depress_timer_active, THREAD_UNINT); - assert(res == THREAD_WAITING); - wake_unlock(thread); - splx(s); + 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; + } - res = thread_block(THREAD_CONTINUE_NULL); - assert(res == THREAD_AWAKENED); + return; + } - s = splsched(); - wake_lock(thread); + *p++ = INT8_MIN; *p++ = 0; + + /* + * 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; } +} - wake_unlock(thread); - splx(s); +static void +preempt_pri_init(void) +{ + bitmap_t *p = sched_preempt_pri; - thread_deallocate(thread); + 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 */ + /* - * Routine: thread_go_locked - * Purpose: - * Start a thread running. - * Conditions: - * thread lock held, IPC locks may be held. - * thread must have been pulled from wait queue under same lock hold. - * Returns: - * KERN_SUCCESS - Thread was set running - * KERN_NOT_WAITING - Thread was not waiting + * Thread wait timer expiration. */ -kern_return_t -thread_go_locked( - thread_t thread, - wait_result_t result) +void +thread_timer_expire( + void *p0, + __unused void *p1) { - assert(thread->at_safe_point == FALSE); - assert(thread->wait_event == NO_EVENT64); - assert(thread->wait_queue == WAIT_QUEUE_NULL); - - if ((thread->state & (TH_WAIT|TH_TERMINATE)) == TH_WAIT) { - thread->state &= ~(TH_WAIT|TH_UNINT); - if (!(thread->state & TH_RUN)) { - thread->state |= TH_RUN; + thread_t thread = p0; + spl_t s; - if (thread->active_callout) - call_thread_unblock(); + assert_thread_magic(thread); - if (!(thread->state & TH_IDLE)) { - _mk_sp_thread_unblock(thread); - hw_atomic_add(&thread->processor_set->run_count, 1); - } + s = splsched(); + thread_lock(thread); + if (--thread->wait_timer_active == 0) { + if (thread->wait_timer_is_set) { + thread->wait_timer_is_set = FALSE; + clear_wait_internal(thread, THREAD_TIMED_OUT); } - - thread->wait_result = result; - return KERN_SUCCESS; } - return KERN_NOT_WAITING; + thread_unlock(thread); + splx(s); } /* - * Routine: thread_mark_wait_locked - * Purpose: - * Mark a thread as waiting. If, given the circumstances, - * it doesn't want to wait (i.e. already aborted), then - * indicate that in the return value. - * Conditions: - * at splsched() and thread is locked. + * thread_unblock: + * + * Unblock thread on wake up. + * + * Returns TRUE if the thread should now be placed on the runqueue. + * + * Thread must be locked. + * + * Called at splsched(). */ -__private_extern__ -wait_result_t -thread_mark_wait_locked( - thread_t thread, - wait_interrupt_t interruptible) +boolean_t +thread_unblock( + thread_t thread, + wait_result_t wresult) { - wait_result_t wait_result; - boolean_t at_safe_point; + boolean_t ready_for_runq = FALSE; + thread_t cthread = current_thread(); + uint32_t new_run_count; + int old_thread_state; - assert(thread == current_thread()); + /* + * Set wait_result. + */ + thread->wait_result = wresult; /* - * The thread may have certain types of interrupts/aborts masked - * off. Even if the wait location says these types of interrupts - * are OK, we have to honor mask settings (outer-scoped code may - * not be able to handle aborts at the moment). + * Cancel pending wait timer. */ - if (interruptible > thread->interrupt_level) - interruptible = thread->interrupt_level; + if (thread->wait_timer_is_set) { + if (timer_call_cancel(&thread->wait_timer)) + thread->wait_timer_active--; + thread->wait_timer_is_set = FALSE; + } - at_safe_point = (interruptible == THREAD_ABORTSAFE); + /* + * Update scheduling state: not waiting, + * set running. + */ + old_thread_state = thread->state; + thread->state = (old_thread_state | TH_RUN) & + ~(TH_WAIT|TH_UNINT|TH_WAIT_REPORT); + + if ((old_thread_state & TH_RUN) == 0) { + uint64_t ctime = mach_approximate_time(); + thread->last_made_runnable_time = thread->last_basepri_change_time = ctime; + timer_start(&thread->runnable_timer, ctime); + + ready_for_runq = TRUE; + + if (old_thread_state & TH_WAIT_REPORT) { + (*thread->sched_call)(SCHED_CALL_UNBLOCK, thread); + } + + /* Update the runnable thread count */ + new_run_count = sched_run_incr(thread); + } else { + /* + * Either the thread is idling in place on another processor, + * or it hasn't finished context switching yet. + */ +#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 + /* + * The run count is only dropped after the context switch completes + * and the thread is still waiting, so we should not run_incr here + */ + new_run_count = sched_run_buckets[TH_BUCKET_RUN]; + } + + + /* + * Calculate deadline for real-time threads. + */ + 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->quantum_remaining = 0; + thread->computation_metered = 0; + thread->reason = AST_NONE; + thread->block_hint = kThreadWaitNone; + + /* 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))) { + 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++; + } + + ledger_credit_thread(thread, thread->t_ledger, + task_ledgers.interrupt_wakeups, 1); + if (pidle) { + ledger_credit_thread(thread, thread->t_ledger, + task_ledgers.platform_idle_wakeups, 1); + } + + } else if (thread_get_tag_internal(cthread) & THREAD_TAG_CALLOUT) { + /* TODO: what about an interrupt that does a wake taken on a callout thread? */ + if (cthread->callout_woken_from_icontext) { + ledger_credit_thread(thread, thread->t_ledger, + task_ledgers.interrupt_wakeups, 1); + thread->thread_callout_interrupt_wakeups++; + + if (cthread->callout_woken_from_platform_idle) { + ledger_credit_thread(thread, 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; + } + +#if KPERF + if (ready_for_runq) { + kperf_make_runnable(thread, aticontext); + } +#endif /* KPERF */ + + KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE, + MACHDBG_CODE(DBG_MACH_SCHED,MACH_MAKE_RUNNABLE) | DBG_FUNC_NONE, + (uintptr_t)thread_tid(thread), thread->sched_pri, thread->wait_result, + sched_run_buckets[TH_BUCKET_RUN], 0); + + DTRACE_SCHED2(wakeup, struct thread *, thread, struct proc *, thread->task->bsd_info); + + return (ready_for_runq); +} + +/* + * Routine: thread_go + * Purpose: + * Unblock and dispatch thread. + * Conditions: + * thread lock held, IPC locks may be held. + * thread must have been pulled from wait queue under same lock hold. + * thread must have been waiting + * Returns: + * KERN_SUCCESS - Thread was set running + * + * TODO: This should return void + */ +kern_return_t +thread_go( + 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->waitq == NULL); + + assert(!(thread->state & (TH_TERMINATE|TH_TERMINATE2))); + assert(thread->state & TH_WAIT); + + + 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_SUCCESS); +} + +/* + * Routine: thread_mark_wait_locked + * Purpose: + * Mark a thread as waiting. If, given the circumstances, + * it doesn't want to wait (i.e. already aborted), then + * indicate that in the return value. + * Conditions: + * at splsched() and thread is locked. + */ +__private_extern__ +wait_result_t +thread_mark_wait_locked( + thread_t thread, + wait_interrupt_t interruptible_orig) +{ + boolean_t at_safe_point; + wait_interrupt_t interruptible = interruptible_orig; + + assert(!(thread->state & (TH_WAIT|TH_IDLE|TH_UNINT|TH_TERMINATE2|TH_WAIT_REPORT))); + + /* + * The thread may have certain types of interrupts/aborts masked + * off. Even if the wait location says these types of interrupts + * are OK, we have to honor mask settings (outer-scoped code may + * not be able to handle aborts at the moment). + */ + interruptible &= TH_OPT_INTMASK; + if (interruptible > (thread->options & TH_OPT_INTMASK)) + interruptible = thread->options & TH_OPT_INTMASK; + + at_safe_point = (interruptible == THREAD_ABORTSAFE); + + if ( interruptible == THREAD_UNINT || + !(thread->sched_flags & TH_SFLAG_ABORT) || + (!at_safe_point && + (thread->sched_flags & TH_SFLAG_ABORTSAFELY))) { + + if ( !(thread->state & TH_TERMINATE)) + DTRACE_SCHED(sleep); + + int state_bits = TH_WAIT; + if (!interruptible) { + state_bits |= TH_UNINT; + } + if (thread->sched_call) { + wait_interrupt_t mask = THREAD_WAIT_NOREPORT_USER; + if (is_kerneltask(thread->task)) { + mask = THREAD_WAIT_NOREPORT_KERNEL; + } + if ((interruptible_orig & mask) == 0) { + state_bits |= TH_WAIT_REPORT; + } + } + thread->state |= state_bits; + thread->at_safe_point = at_safe_point; + + /* TODO: pass this through assert_wait instead, have + * assert_wait just take a struct as an argument */ + assert(!thread->block_hint); + thread->block_hint = thread->pending_block_hint; + thread->pending_block_hint = kThreadWaitNone; - if ((interruptible == THREAD_UNINT) || - !(thread->state & TH_ABORT) || - (!at_safe_point && (thread->state & TH_ABORT_SAFELY))) { - thread->state |= (interruptible) ? TH_WAIT : (TH_WAIT | TH_UNINT); - thread->at_safe_point = at_safe_point; - thread->sleep_stamp = sched_tick; return (thread->wait_result = THREAD_WAITING); - } else if (thread->state & TH_ABORT_SAFELY) { - thread->state &= ~(TH_ABORT|TH_ABORT_SAFELY); + } else { + if (thread->sched_flags & TH_SFLAG_ABORTSAFELY) + thread->sched_flags &= ~TH_SFLAG_ABORTED_MASK; } + thread->pending_block_hint = kThreadWaitNone; + return (thread->wait_result = THREAD_INTERRUPTED); } @@ -532,54 +948,11 @@ thread_interrupt_level( wait_interrupt_t new_level) { thread_t thread = current_thread(); - wait_interrupt_t result = thread->interrupt_level; - - thread->interrupt_level = new_level; - return result; -} - -/* - * Routine: assert_wait_timeout - * Purpose: - * Assert that the thread intends to block, - * waiting for a timeout (no user known event). - */ -unsigned int assert_wait_timeout_event; - -wait_result_t -assert_wait_timeout( - mach_msg_timeout_t msecs, - wait_interrupt_t interruptible) -{ - wait_result_t res; - - res = assert_wait((event_t)&assert_wait_timeout_event, interruptible); - if (res == THREAD_WAITING) - thread_set_timer(msecs, 1000*NSEC_PER_USEC); - return res; -} - -/* - * Check to see if an assert wait is possible, without actually doing one. - * This is used by debug code in locks and elsewhere to verify that it is - * always OK to block when trying to take a blocking lock (since waiting - * for the actual assert_wait to catch the case may make it hard to detect - * this case. - */ -boolean_t -assert_wait_possible(void) -{ - - thread_t thread; - extern unsigned int debug_mode; + wait_interrupt_t result = thread->options & TH_OPT_INTMASK; -#if DEBUG - if(debug_mode) return TRUE; /* Always succeed in debug mode */ -#endif - - thread = current_thread(); + thread->options = (thread->options & ~TH_OPT_INTMASK) | (new_level & TH_OPT_INTMASK); - return (thread == NULL || wait_queue_assert_possible(thread)); + return result; } /* @@ -593,244 +966,289 @@ 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); - assert(assert_wait_possible()); + 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); + struct waitq *waitq; + waitq = global_eventq(event); + return waitq_assert_wait64(waitq, CAST_EVENT64_T(event), interruptible, TIMEOUT_WAIT_FOREVER); } - /* - * 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. + * assert_wait_queue: * - * This is the simple lock sleep interface for components that use a - * faster version of simple_lock() than is provided by usimple_lock(). + * Return the global waitq for the specified event */ -__private_extern__ wait_result_t -thread_sleep_fast_usimple_lock( - event_t event, - simple_lock_t lock, - wait_interrupt_t interruptible) +struct waitq * +assert_wait_queue( + event_t event) { - 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; + return global_eventq(event); } - -/* - * thread_sleep_usimple_lock: - * - * Cause the current thread to wait until the specified event - * occurs. The specified usimple_lock is unlocked before releasing - * the cpu and re-acquired as part of waking up. - * - * This is the simple lock sleep interface for components where - * simple_lock() is defined in terms of usimple_lock(). - */ wait_result_t -thread_sleep_usimple_lock( - event_t event, - usimple_lock_t lock, - wait_interrupt_t interruptible) +assert_wait_timeout( + event_t event, + wait_interrupt_t interruptible, + uint32_t interval, + uint32_t scale_factor) { - wait_result_t res; + thread_t thread = current_thread(); + wait_result_t wresult; + uint64_t deadline; + spl_t s; - res = assert_wait(event, interruptible); - if (res == THREAD_WAITING) { - usimple_unlock(lock); - res = thread_block(THREAD_CONTINUE_NULL); - usimple_lock(lock); - } - return res; + if (__improbable(event == NO_EVENT)) + panic("%s() called with NO_EVENT", __func__); + + struct waitq *waitq; + waitq = global_eventq(event); + + s = splsched(); + waitq_lock(waitq); + + clock_interval_to_deadline(interval, scale_factor, &deadline); + + 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; } -/* - * 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) +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) { - wait_result_t res; + thread_t thread = current_thread(); + wait_result_t wresult; + uint64_t deadline; + uint64_t abstime; + uint64_t slop; + uint64_t now; + spl_t s; - res = assert_wait(event, interruptible); - if (res == THREAD_WAITING) { - mutex_unlock(mutex); - res = thread_block(THREAD_CONTINUE_NULL); - mutex_lock(mutex); - } - return res; + 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); + + wresult = waitq_assert_wait64_locked(waitq, CAST_EVENT64_T(event), + interruptible, + urgency, deadline, slop, + thread); + + waitq_unlock(waitq); + splx(s); + return wresult; } - -/* - * thread_sleep_mutex_deadline: - * - * 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. - * - * JMM - Add hint to make sure mutex is available before rousting - */ + wait_result_t -thread_sleep_mutex_deadline( - event_t event, - mutex_t *mutex, - uint64_t deadline, - wait_interrupt_t interruptible) +assert_wait_deadline( + event_t event, + wait_interrupt_t interruptible, + uint64_t deadline) { - wait_result_t res; + thread_t thread = current_thread(); + wait_result_t wresult; + spl_t s; - res = assert_wait(event, interruptible); - if (res == THREAD_WAITING) { - mutex_unlock(mutex); - thread_set_timer_deadline(deadline); - res = thread_block(THREAD_CONTINUE_NULL); - if (res != THREAD_TIMED_OUT) - thread_cancel_timer(); - mutex_lock(mutex); - } - return res; + if (__improbable(event == NO_EVENT)) + panic("%s() called with NO_EVENT", __func__); + + struct waitq *waitq; + waitq = global_eventq(event); + + s = splsched(); + waitq_lock(waitq); + + 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; } -/* - * 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. - * - * JMM - Add hint to make sure mutex is available before rousting - */ wait_result_t -thread_sleep_lock_write( - event_t event, - lock_t *lock, - wait_interrupt_t interruptible) +assert_wait_deadline_with_leeway( + event_t event, + wait_interrupt_t interruptible, + wait_timeout_urgency_t urgency, + uint64_t deadline, + uint64_t leeway) { - wait_result_t res; + thread_t thread = current_thread(); + wait_result_t wresult; + spl_t s; - res = assert_wait(event, interruptible); - if (res == THREAD_WAITING) { - lock_write_done(lock); - res = thread_block(THREAD_CONTINUE_NULL); - lock_write(lock); - } - return res; -} + if (__improbable(event == NO_EVENT)) + panic("%s() called with NO_EVENT", __func__); + struct waitq *waitq; + waitq = global_eventq(event); + + s = splsched(); + waitq_lock(waitq); + + 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, + urgency, deadline, leeway, + thread); + waitq_unlock(waitq); + splx(s); + return wresult; +} /* - * thread_sleep_funnel: + * thread_isoncpu: * - * Cause the current thread to wait until the specified event - * occurs. If the thread is funnelled, the funnel will be released - * before giving up the cpu. The funnel will be re-acquired before returning. - * - * JMM - Right now the funnel is dropped and re-acquired inside - * thread_block(). At some point, this may give thread_block() a hint. + * 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_funnel( - event_t event, - wait_interrupt_t interruptible) +static inline boolean_t +thread_isoncpu(thread_t thread) { - wait_result_t res; + /* Not running or runnable */ + if (!(thread->state & TH_RUN)) + return (FALSE); - res = assert_wait(event, interruptible); - if (res == THREAD_WAITING) { - res = thread_block(THREAD_CONTINUE_NULL); - } - return res; + /* Waiting on a runqueue, not currently running */ + /* TODO: This is invalid - it can get dequeued without thread lock, but not context switched. */ + if (thread->runq != PROCESSOR_NULL) + return (FALSE); + + /* + * Thread does not have a stack yet + * It could be on the stack alloc queue or preparing to be invoked + */ + if (!thread->kernel_stack) + return (FALSE); + + /* + * Thread must be running on a processor, or + * about to run, or just did run. In all these + * cases, an AST to the processor is needed + * to guarantee that the thread is kicked out + * of userspace and the processor has + * context switched (and saved register state). + */ + return (TRUE); } /* - * thread_[un]stop(thread) - * Once a thread has blocked interruptibly (via assert_wait) prevent - * it from running until thread_unstop. + * thread_stop: * - * If someone else has already stopped the thread, wait for the - * stop to be cleared, and then stop it again. + * Force a preemption point for a thread and wait + * 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) * - * Return FALSE if interrupted. + * The thread must enter a wait state and stop via a + * separate means. * - * NOTE: thread_hold/thread_suspend should be called on the activation - * before calling thread_stop. TH_SUSP is only recognized when - * a thread blocks and only prevents clear_wait/thread_wakeup - * from restarting an interruptible wait. The wake_active flag is - * used to indicate that someone is waiting on the thread. + * Returns FALSE if interrupted. */ boolean_t thread_stop( - thread_t thread) + thread_t thread, + boolean_t until_not_runnable) { - spl_t s = splsched(); + wait_result_t wresult; + spl_t s = splsched(); + boolean_t oncpu; wake_lock(thread); + thread_lock(thread); while (thread->state & TH_SUSP) { - wait_result_t result; - thread->wake_active = TRUE; - result = assert_wait(&thread->wake_active, THREAD_ABORTSAFE); + thread_unlock(thread); + + wresult = assert_wait(&thread->wake_active, THREAD_ABORTSAFE); wake_unlock(thread); splx(s); - if (result == THREAD_WAITING) - result = thread_block(THREAD_CONTINUE_NULL); + if (wresult == THREAD_WAITING) + wresult = thread_block(THREAD_CONTINUE_NULL); - if (result != THREAD_AWAKENED) + if (wresult != THREAD_AWAKENED) return (FALSE); s = splsched(); wake_lock(thread); + thread_lock(thread); } - thread_lock(thread); thread->state |= TH_SUSP; - while (thread->state & TH_RUN) { - wait_result_t result; - processor_t processor = thread->last_processor; - - if ( processor != PROCESSOR_NULL && - processor->state == PROCESSOR_RUNNING && - processor->cpu_data->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; - result = assert_wait(&thread->wake_active, THREAD_ABORTSAFE); + thread_unlock(thread); + + wresult = assert_wait(&thread->wake_active, THREAD_ABORTSAFE); wake_unlock(thread); splx(s); - if (result == THREAD_WAITING) - result = thread_block(THREAD_CONTINUE_NULL); + if (wresult == THREAD_WAITING) + wresult = thread_block(THREAD_CONTINUE_NULL); - if (result != THREAD_AWAKENED) { + if (wresult != THREAD_AWAKENED) { thread_unstop(thread); return (FALSE); } @@ -843,13 +1261,24 @@ 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); } /* - * Clear TH_SUSP and if the thread has been stopped and is now runnable, - * put it back on the run queue. + * thread_unstop: + * + * Release a previous stop request and set + * the thread running if appropriate. + * + * Use only after a successful stop operation. */ void thread_unstop( @@ -860,25 +1289,19 @@ thread_unstop( wake_lock(thread); thread_lock(thread); - if ((thread->state & (TH_RUN|TH_WAIT|TH_SUSP)) == TH_SUSP) { - thread->state &= ~TH_SUSP; - thread->state |= TH_RUN; + assert((thread->state & (TH_RUN|TH_WAIT|TH_SUSP)) != TH_SUSP); - assert(!(thread->state & TH_IDLE)); - _mk_sp_thread_unblock(thread); - hw_atomic_add(&thread->processor_set->run_count, 1); - } - 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; } } @@ -889,37 +1312,49 @@ thread_unstop( } /* - * Wait for the thread's RUN bit to clear + * thread_wait: + * + * Wait for a thread to stop running. (non-interruptible) + * */ -boolean_t +void thread_wait( - thread_t thread) + thread_t thread, + boolean_t until_not_runnable) { + wait_result_t wresult; + boolean_t oncpu; + processor_t processor; spl_t s = splsched(); wake_lock(thread); thread_lock(thread); - while (thread->state & TH_RUN) { - wait_result_t result; - 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->cpu_data->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; - result = assert_wait(&thread->wake_active, THREAD_ABORTSAFE); + thread_unlock(thread); + + wresult = assert_wait(&thread->wake_active, THREAD_UNINT); wake_unlock(thread); splx(s); - if (result == THREAD_WAITING) - result = thread_block(THREAD_CONTINUE_NULL); - - if (result != THREAD_AWAKENED) - return (FALSE); + if (wresult == THREAD_WAITING) + thread_block(THREAD_CONTINUE_NULL); s = splsched(); wake_lock(thread); @@ -929,8 +1364,6 @@ thread_wait( thread_unlock(thread); wake_unlock(thread); splx(s); - - return (TRUE); } /* @@ -952,38 +1385,39 @@ thread_wait( __private_extern__ kern_return_t clear_wait_internal( thread_t thread, - wait_result_t result) + wait_result_t wresult) { - wait_queue_t wq = thread->wait_queue; - kern_return_t ret; - int loop_count; - - loop_count = 0; + uint32_t i = LockTimeOutUsec; + struct waitq *waitq = thread->waitq; + do { - if ((result == THREAD_INTERRUPTED) && (thread->state & TH_UNINT)) - return KERN_FAILURE; + 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; /* we know it moved */ - } + if (waitq != thread->waitq) + return KERN_NOT_WAITING; continue; } } - ret = thread_go_locked(thread, result); - return ret; - } while (++loop_count < LockTimeOut); - panic("clear_wait_internal: deadlock: thread=0x%x, wq=0x%x, cpu=%d\n", - thread, wq, cpu_number()); - return KERN_FAILURE; + + /* 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=%p, wq=%p, cpu=%d\n", + thread, waitq, cpu_number()); + + return (KERN_FAILURE); } @@ -1023,1966 +1457,4419 @@ 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); } /* - * thread_bind: - * - * Force a thread to execute on the specified processor. - * If the thread is currently executing, it may wait until its - * time slice is up before switching onto the specified processor. + * 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__); + + if (__improbable(thread == THREAD_NULL)) + panic("%s() called with THREAD_NULL", __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. * - * A processor of PROCESSOR_NULL causes the thread to be unbound. - * xxx - DO NOT export this to users. + * Requires woken thread to un-promote itself when done. */ -void +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 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. + * + * XXX - DO NOT export this to users - XXX + */ +processor_t thread_bind( - register thread_t thread, - processor_t processor) + processor_t processor) { - spl_t s; + thread_t self = current_thread(); + processor_t prev; + spl_t s; s = splsched(); - thread_lock(thread); - thread_bind_locked(thread, processor); - thread_unlock(thread); + thread_lock(self); + + prev = thread_bind_internal(self, processor); + + thread_unlock(self); splx(s); + + return (prev); } /* - * Select a thread for this processor (the current processor) to run. - * May select the current thread, which must already be locked. + * 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. */ -thread_t -thread_select( - register processor_t myprocessor) + +static processor_t +thread_bind_internal( + thread_t thread, + processor_t processor) { - register thread_t thread; - processor_set_t pset; - register run_queue_t runq = &myprocessor->runq; - boolean_t other_runnable; + processor_t prev; - /* - * Check for other non-idle runnable threads. + /* */ + assert(thread->sched_pri < BASEPRI_RTQUEUES); + /* A thread can't be bound if it's sitting on a (potentially incorrect) runqueue */ + assert(thread->runq == PROCESSOR_NULL); + + KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_THREAD_BIND), thread_tid(thread), processor ? (uintptr_t)processor->cpu_id : (uintptr_t)-1, 0, 0, 0); + + prev = thread->bound_processor; + thread->bound_processor = processor; + + return (prev); +} + +/* + * thread_vm_bind_group_add: + * + * The "VM bind group" is a special mechanism to mark a collection + * of threads from the VM subsystem that, in general, should be scheduled + * with only one CPU of parallelism. To accomplish this, we initially + * bind all the threads to the master processor, which has the effect + * that only one of the threads in the group can execute at once, including + * preempting threads in the group that are a lower priority. Future + * mechanisms may use more dynamic mechanisms to prevent the collection + * of VM threads from using more CPU time than desired. + * + * The current implementation can result in priority inversions where + * compute-bound priority 95 or realtime threads that happen to have + * landed on the master processor prevent the VM threads from running. + * When this situation is detected, we unbind the threads for one + * scheduler tick to allow the scheduler to run the threads an + * additional CPUs, before restoring the binding (assuming high latency + * is no longer a problem). + */ + +/* + * The current max is provisioned for: + * vm_compressor_swap_trigger_thread (92) + * 2 x vm_pageout_iothread_internal (92) when vm_restricted_to_single_processor==TRUE + * vm_pageout_continue (92) + * memorystatus_thread (95) + */ +#define MAX_VM_BIND_GROUP_COUNT (5) +decl_simple_lock_data(static,sched_vm_group_list_lock); +static thread_t sched_vm_group_thread_list[MAX_VM_BIND_GROUP_COUNT]; +static int sched_vm_group_thread_count; +static boolean_t sched_vm_group_temporarily_unbound = FALSE; + +void +thread_vm_bind_group_add(void) +{ + thread_t self = current_thread(); + + thread_reference_internal(self); + self->options |= TH_OPT_SCHED_VM_GROUP; + + simple_lock(&sched_vm_group_list_lock); + assert(sched_vm_group_thread_count < MAX_VM_BIND_GROUP_COUNT); + sched_vm_group_thread_list[sched_vm_group_thread_count++] = self; + simple_unlock(&sched_vm_group_list_lock); + + thread_bind(master_processor); + + /* Switch to bound processor if not already there */ + thread_block(THREAD_CONTINUE_NULL); +} + +static void +sched_vm_group_maintenance(void) +{ + uint64_t ctime = mach_absolute_time(); + uint64_t longtime = ctime - sched_tick_interval; + int i; + spl_t s; + boolean_t high_latency_observed = FALSE; + boolean_t runnable_and_not_on_runq_observed = FALSE; + boolean_t bind_target_changed = FALSE; + processor_t bind_target = PROCESSOR_NULL; + + /* Make sure nobody attempts to add new threads while we are enumerating them */ + simple_lock(&sched_vm_group_list_lock); + + s = splsched(); + + for (i=0; i < sched_vm_group_thread_count; i++) { + thread_t thread = sched_vm_group_thread_list[i]; + assert(thread != THREAD_NULL); + thread_lock(thread); + if ((thread->state & (TH_RUN|TH_WAIT)) == TH_RUN) { + if (thread->runq != PROCESSOR_NULL && thread->last_made_runnable_time < longtime) { + high_latency_observed = TRUE; + } else if (thread->runq == PROCESSOR_NULL) { + /* There are some cases where a thread be transitiong that also fall into this case */ + runnable_and_not_on_runq_observed = TRUE; + } + } + thread_unlock(thread); + + if (high_latency_observed && runnable_and_not_on_runq_observed) { + /* All the things we are looking for are true, stop looking */ + break; + } + } + + splx(s); + + if (sched_vm_group_temporarily_unbound) { + /* If we turned off binding, make sure everything is OK before rebinding */ + if (!high_latency_observed) { + /* rebind */ + bind_target_changed = TRUE; + bind_target = master_processor; + sched_vm_group_temporarily_unbound = FALSE; /* might be reset to TRUE if change cannot be completed */ + } + } else { + /* + * Check if we're in a bad state, which is defined by high + * latency with no core currently executing a thread. If a + * single thread is making progress on a CPU, that means the + * binding concept to reduce parallelism is working as + * designed. + */ + if (high_latency_observed && !runnable_and_not_on_runq_observed) { + /* unbind */ + bind_target_changed = TRUE; + bind_target = PROCESSOR_NULL; + sched_vm_group_temporarily_unbound = TRUE; + } + } + + if (bind_target_changed) { + s = splsched(); + for (i=0; i < sched_vm_group_thread_count; i++) { + thread_t thread = sched_vm_group_thread_list[i]; + boolean_t removed; + assert(thread != THREAD_NULL); + + thread_lock(thread); + removed = thread_run_queue_remove(thread); + if (removed || ((thread->state & (TH_RUN | TH_WAIT)) == TH_WAIT)) { + thread_bind_internal(thread, bind_target); + } else { + /* + * Thread was in the middle of being context-switched-to, + * or was in the process of blocking. To avoid switching the bind + * state out mid-flight, defer the change if possible. + */ + if (bind_target == PROCESSOR_NULL) { + thread_bind_internal(thread, bind_target); + } else { + sched_vm_group_temporarily_unbound = TRUE; /* next pass will try again */ + } + } + + if (removed) { + thread_run_queue_reinsert(thread, SCHED_PREEMPT | SCHED_TAILQ); + } + thread_unlock(thread); + } + splx(s); + } + + simple_unlock(&sched_vm_group_list_lock); +} + +/* Invoked prior to idle entry to determine if, on SMT capable processors, an SMT + * rebalancing opportunity exists when a core is (instantaneously) idle, but + * other SMT-capable cores may be over-committed. TODO: some possible negatives: + * IPI thrash if this core does not remain idle following the load balancing ASTs + * Idle "thrash", when IPI issue is followed by idle entry/core power down + * followed by a wakeup shortly thereafter. + */ + +#if (DEVELOPMENT || DEBUG) +int sched_smt_balance = 1; +#endif + +#if __SMP__ +/* Invoked with pset locked, returns with pset unlocked */ +void +sched_SMT_balance(processor_t cprocessor, processor_set_t cpset) { + processor_t ast_processor = NULL; + +#if (DEVELOPMENT || DEBUG) + if (__improbable(sched_smt_balance == 0)) + goto smt_balance_exit; +#endif + + assert(cprocessor == current_processor()); + if (cprocessor->is_SMT == FALSE) + goto smt_balance_exit; + + processor_t sib_processor = cprocessor->processor_secondary ? cprocessor->processor_secondary : cprocessor->processor_primary; + + /* Determine if both this processor and its sibling are idle, + * indicating an SMT rebalancing opportunity. */ - pset = myprocessor->processor_set; - thread = myprocessor->cpu_data->active_thread; + if (sib_processor->state != PROCESSOR_IDLE) + goto smt_balance_exit; + + processor_t sprocessor; + + sched_ipi_type_t ipi_type = SCHED_IPI_NONE; + uint64_t running_secondary_map = (cpset->cpu_state_map[PROCESSOR_RUNNING] & + ~cpset->primary_map); + for (int cpuid = lsb_first(running_secondary_map); cpuid >= 0; cpuid = lsb_next(running_secondary_map, cpuid)) { + sprocessor = processor_array[cpuid]; + if ((sprocessor->processor_primary->state == PROCESSOR_RUNNING) && + (sprocessor->current_pri < BASEPRI_RTQUEUES)) { + + ipi_type = sched_ipi_action(sprocessor, NULL, false, SCHED_IPI_EVENT_SMT_REBAL); + if (ipi_type != SCHED_IPI_NONE) { + assert(sprocessor != cprocessor); + ast_processor = sprocessor; + break; + } + } + } + +smt_balance_exit: + pset_unlock(cpset); + + if (ast_processor) { + KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_SMT_BALANCE), ast_processor->cpu_id, ast_processor->state, ast_processor->processor_primary->state, 0, 0); + sched_ipi_perform(ast_processor, ipi_type); + } +} +#else +/* Invoked with pset locked, returns with pset unlocked */ +void +sched_SMT_balance(__unused processor_t cprocessor, processor_set_t cpset) +{ + pset_unlock(cpset); +} +#endif /* __SMP__ */ + +static processor_t choose_processor_for_realtime_thread(processor_set_t pset); +static bool all_available_primaries_are_running_realtime_threads(processor_set_t pset); +int sched_allow_rt_smt = 1; + +/* + * thread_select: + * + * Select a new thread for the current processor to execute. + * + * May select the current thread, which must be locked. + */ +static thread_t +thread_select(thread_t thread, + processor_t processor, + ast_t *reason) +{ + processor_set_t pset = processor->processor_set; + thread_t new_thread = THREAD_NULL; + + assert(processor == current_processor()); + assert((thread->state & (TH_RUN|TH_TERMINATE2)) == TH_RUN); + + do { + /* + * Update the priority. + */ + if (SCHED(can_update_priority)(thread)) + SCHED(update_priority)(thread); + + processor_state_update_from_thread(processor, thread); + + pset_lock(pset); + + assert(processor->state != PROCESSOR_OFF_LINE); + + if (!processor->is_recommended) { + /* + * The performance controller has provided a hint to not dispatch more threads, + * unless they are bound to us (and thus we are the only option + */ + if (!SCHED(processor_bound_count)(processor)) { + goto idle; + } + } else if (processor->processor_primary != processor) { + /* + * Should this secondary SMT processor attempt to find work? For pset runqueue systems, + * we should look for work only under the same conditions that choose_processor() + * would have assigned work, which is when all primary processors have been assigned work. + * + * An exception is that bound threads are dispatched to a processor without going through + * choose_processor(), so in those cases we should continue trying to dequeue work. + */ + if (!SCHED(processor_bound_count)(processor)) { + if ((pset->recommended_bitmask & pset->primary_map & pset->cpu_state_map[PROCESSOR_IDLE]) != 0) { + goto idle; + } + + /* There are no idle primaries */ + + if (processor->processor_primary->current_pri >= BASEPRI_RTQUEUES) { + bool secondary_can_run_realtime_thread = sched_allow_rt_smt && rt_runq_count(pset) && all_available_primaries_are_running_realtime_threads(pset); + if (!secondary_can_run_realtime_thread) { + goto idle; + } + } + } + } + + /* + * 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. + */ + + /* i.e. not waiting, not TH_SUSP'ed */ + boolean_t still_running = ((thread->state & (TH_TERMINATE|TH_IDLE|TH_WAIT|TH_RUN|TH_SUSP)) == TH_RUN); + + /* + * Threads running on SMT processors are forced to context switch. Don't rebalance realtime threads. + * TODO: This should check if it's worth it to rebalance, i.e. 'are there any idle primary processors' + */ + boolean_t needs_smt_rebalance = (thread->sched_pri < BASEPRI_RTQUEUES && processor->processor_primary != processor); + + boolean_t affinity_mismatch = (thread->affinity_set != AFFINITY_SET_NULL && thread->affinity_set->aset_pset != pset); + + boolean_t bound_elsewhere = (thread->bound_processor != PROCESSOR_NULL && thread->bound_processor != processor); + + boolean_t avoid_processor = (SCHED(avoid_processor_enabled) && SCHED(thread_avoid_processor)(processor, thread)); + + if (still_running && !needs_smt_rebalance && !affinity_mismatch && !bound_elsewhere && !avoid_processor) { + /* + * This thread is eligible to keep running on this processor. + * + * 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(pset) > 0) { + + rt_lock_lock(pset); + + if (rt_runq_count(pset) > 0) { + + thread_t next_rt = qe_queue_first(&SCHED(rt_runq)(pset)->queue, struct thread, runq_links); + + 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; + } + } + + rt_lock_unlock(pset); + } + + /* This is still the best RT thread to run. */ + processor->deadline = thread->realtime.deadline; + + sched_update_pset_load_average(pset); + + processor_t next_rt_processor = PROCESSOR_NULL; + sched_ipi_type_t next_rt_ipi_type = SCHED_IPI_NONE; + + if (rt_runq_count(pset) > 0) { + next_rt_processor = choose_processor_for_realtime_thread(pset); + if (next_rt_processor) { + next_rt_ipi_type = sched_ipi_action(next_rt_processor, NULL, false, SCHED_IPI_EVENT_PREEMPT); + } + } + pset_unlock(pset); + + if (next_rt_processor) { + sched_ipi_perform(next_rt_processor, next_rt_ipi_type); + } + + return (thread); + } + + if ((rt_runq_count(pset) == 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; + + sched_update_pset_load_average(pset); + pset_unlock(pset); + + return (thread); + } + } else { + /* + * This processor must context switch. + * If it's due to a rebalance, we should aggressively find this thread a new home. + */ + if (needs_smt_rebalance || affinity_mismatch || bound_elsewhere || avoid_processor) + *reason |= AST_REBALANCE; + } - /* Update the thread's priority */ - if (thread->sched_stamp != sched_tick) - update_priority(thread); + /* OK, so we're not going to run the current thread. Look at the RT queue. */ + if (rt_runq_count(pset) > 0) { + + rt_lock_lock(pset); + + if (rt_runq_count(pset) > 0) { + thread_t next_rt = qe_queue_first(&SCHED(rt_runq)(pset)->queue, struct thread, runq_links); + + if (__probable((next_rt->bound_processor == PROCESSOR_NULL || + (next_rt->bound_processor == processor)))) { +pick_new_rt_thread: + new_thread = qe_dequeue_head(&SCHED(rt_runq)(pset)->queue, struct thread, runq_links); + + new_thread->runq = PROCESSOR_NULL; + SCHED_STATS_RUNQ_CHANGE(&SCHED(rt_runq)(pset)->runq_stats, rt_runq_count(pset)); + rt_runq_count_decr(pset); + + processor->deadline = new_thread->realtime.deadline; + processor_state_update_from_thread(processor, new_thread); + + rt_lock_unlock(pset); + sched_update_pset_load_average(pset); + + processor_t ast_processor = PROCESSOR_NULL; + processor_t next_rt_processor = PROCESSOR_NULL; + sched_ipi_type_t ipi_type = SCHED_IPI_NONE; + sched_ipi_type_t next_rt_ipi_type = SCHED_IPI_NONE; + + if (processor->processor_secondary != NULL) { + processor_t sprocessor = processor->processor_secondary; + if ((sprocessor->state == PROCESSOR_RUNNING) || (sprocessor->state == PROCESSOR_DISPATCHING)) { + ipi_type = sched_ipi_action(sprocessor, NULL, false, SCHED_IPI_EVENT_SMT_REBAL); + ast_processor = sprocessor; + } + } + if (rt_runq_count(pset) > 0) { + next_rt_processor = choose_processor_for_realtime_thread(pset); + if (next_rt_processor) { + next_rt_ipi_type = sched_ipi_action(next_rt_processor, NULL, false, SCHED_IPI_EVENT_PREEMPT); + } + } + pset_unlock(pset); + + if (ast_processor) { + sched_ipi_perform(ast_processor, ipi_type); + } + + if (next_rt_processor) { + sched_ipi_perform(next_rt_processor, next_rt_ipi_type); + } + + return (new_thread); + } + } + + rt_lock_unlock(pset); + } + + processor->deadline = UINT64_MAX; + + /* No RT threads, so let's look at the regular threads. */ + if ((new_thread = SCHED(choose_thread)(processor, MINPRI, *reason)) != THREAD_NULL) { + sched_update_pset_load_average(pset); + processor_state_update_from_thread(processor, new_thread); + pset_unlock(pset); + return (new_thread); + } + +#if __SMP__ + if (SCHED(steal_thread_enabled)) { + /* + * No runnable threads, attempt to steal + * from other processors. Returns with pset lock dropped. + */ + + if ((new_thread = SCHED(steal_thread)(pset)) != THREAD_NULL) { + return (new_thread); + } + + /* + * If other threads have appeared, shortcut + * around again. + */ + if (!SCHED(processor_queue_empty)(processor) || rt_runq_count(pset) > 0) + continue; + + pset_lock(pset); + } +#endif + + idle: + /* + * Nothing is runnable, so set this processor idle if it + * was running. + */ + if (processor->state == PROCESSOR_RUNNING) { + pset_update_processor_state(pset, processor, PROCESSOR_IDLE); + } + +#if __SMP__ + /* Invoked with pset locked, returns with pset unlocked */ + SCHED(processor_balance)(processor, pset); +#else + pset_unlock(pset); +#endif + +#if CONFIG_SCHED_IDLE_IN_PLACE + /* + * Choose idle thread if fast idle is not possible. + */ + if (processor->processor_primary != processor) + return (processor->idle_thread); + + if ((thread->state & (TH_IDLE|TH_TERMINATE|TH_SUSP)) || !(thread->state & TH_WAIT) || thread->wake_active || thread->sched_pri >= BASEPRI_RTQUEUES) + return (processor->idle_thread); + + /* + * Perform idling activities directly without a + * context switch. Return dispatched thread, + * else check again for a runnable thread. + */ + new_thread = thread_select_idle(thread, processor); + +#else /* !CONFIG_SCHED_IDLE_IN_PLACE */ + + /* + * 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. + */ + new_thread = processor->idle_thread; + +#endif /* !CONFIG_SCHED_IDLE_IN_PLACE */ + + } while (new_thread == THREAD_NULL); + + return (new_thread); +} + +#if CONFIG_SCHED_IDLE_IN_PLACE +/* + * thread_select_idle: + * + * Idle the processor using the current thread context. + * + * Called with thread locked, then dropped and relocked. + */ +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_state_update_idle(procssor); + + /* Reload precise timing global policy to thread-local policy */ + thread->precise_user_kernel_time = use_precise_user_kernel_time(thread); + + thread_unlock(thread); + + /* + * Switch execution timing to processor idle thread. + */ + processor->last_dispatch = mach_absolute_time(); + +#ifdef CONFIG_MACH_APPROXIMATE_TIME + commpage_update_mach_approximate_time(processor->last_dispatch); +#endif + + thread->last_run_time = processor->last_dispatch; + processor_timer_switch_thread(processor->last_dispatch, + &processor->idle_thread->system_timer); + PROCESSOR_DATA(processor, kernel_timer) = &processor->idle_thread->system_timer; + + + /* + * Cancel the quantum timer while idling. + */ + timer_call_quantum_timer_cancel(&processor->quantum_timer); + processor->first_timeslice = FALSE; + + if (thread->sched_call) { + (*thread->sched_call)(SCHED_CALL_BLOCK, thread); + } + + thread_tell_urgency(THREAD_URGENCY_NONE, 0, 0, 0, NULL); + + /* + * Enable interrupts and perform idling activities. No + * preemption due to TH_IDLE being set. + */ + spllo(); new_thread = processor_idle(thread, processor); + + /* + * Return at splsched. + */ + if (thread->sched_call) { + (*thread->sched_call)(SCHED_CALL_UNBLOCK, thread); + } + + thread_lock(thread); + + /* + * 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)) { + uint64_t time_now = processor->last_dispatch = mach_absolute_time(); + processor_timer_switch_thread(time_now, &thread->system_timer); + timer_update(&thread->runnable_timer, time_now); + PROCESSOR_DATA(processor, kernel_timer) = &thread->system_timer; + thread_quantum_init(thread); + processor->quantum_end = time_now + thread->quantum_remaining; + timer_call_quantum_timer_enter(&processor->quantum_timer, + thread, processor->quantum_end, time_now); + processor->first_timeslice = TRUE; + + thread->computation_epoch = time_now; + } + + 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_invoke + * + * Called at splsched with neither thread locked. + * + * 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) + */ +static boolean_t +thread_invoke( + thread_t self, + thread_t thread, + ast_t reason) +{ + if (__improbable(get_preemption_level() != 0)) { + int pl = get_preemption_level(); + panic("thread_invoke: preemption_level %d, possible cause: %s", + pl, (pl < 0 ? "unlocking an unlocked mutex or spinlock" : + "blocking while holding a spinlock, or within interrupt context")); + } + + thread_continue_t continuation = self->continuation; + void *parameter = self->parameter; + processor_t processor; + + uint64_t ctime = mach_absolute_time(); + +#ifdef CONFIG_MACH_APPROXIMATE_TIME + commpage_update_mach_approximate_time(ctime); +#endif + +#if defined(CONFIG_SCHED_TIMESHARE_CORE) + if ((thread->state & TH_IDLE) == 0) + sched_timeshare_consider_maintenance(ctime); +#endif + +#if MONOTONIC + mt_sched_update(self); +#endif /* MONOTONIC */ + + assert_thread_magic(self); + assert(self == current_thread()); + assert(self->runq == PROCESSOR_NULL); + assert((self->state & (TH_RUN|TH_TERMINATE2)) == TH_RUN); + + thread_lock(thread); + + 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); + + /* Reload precise timing global policy to thread-local policy */ + thread->precise_user_kernel_time = use_precise_user_kernel_time(thread); + + /* Update SFI class based on other factors */ + thread->sfi_class = sfi_thread_classify(thread); + + /* Update the same_pri_latency for the thread (used by perfcontrol callouts) */ + thread->same_pri_latency = ctime - thread->last_basepri_change_time; + /* + * In case a base_pri update happened between the timestamp and + * taking the thread lock + */ + if (ctime <= thread->last_basepri_change_time) + thread->same_pri_latency = ctime - thread->last_made_runnable_time; + + /* Allow realtime threads to hang onto a stack. */ + if ((self->sched_mode == TH_MODE_REALTIME) && !self->reserved_stack) + self->reserved_stack = self->kernel_stack; + + /* Prepare for spin debugging */ +#if INTERRUPT_MASKED_DEBUG + ml_spin_debug_clear(thread); +#endif + + 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; + + /* + * Context switch by performing a stack handoff. + */ + continuation = thread->continuation; + parameter = thread->parameter; + + processor = current_processor(); + processor->active_thread = thread; + processor_state_update_from_thread(processor, thread); + + 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); + + self->reason = reason; + + processor->last_dispatch = ctime; + self->last_run_time = ctime; + processor_timer_switch_thread(ctime, &thread->system_timer); + timer_update(&thread->runnable_timer, ctime); + 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_update(PROCESSOR_DATA(processor, current_state), ctime); + } + + KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE, + MACHDBG_CODE(DBG_MACH_SCHED, MACH_STACK_HANDOFF)|DBG_FUNC_NONE, + self->reason, (uintptr_t)thread_tid(thread), self->sched_pri, thread->sched_pri, 0); + + if ((thread->chosen_processor != processor) && (thread->chosen_processor != 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); + +#if KPERF + kperf_off_cpu(self); +#endif /* KPERF */ + + TLOG(1, "thread_invoke: calling stack_handoff\n"); + stack_handoff(self, thread); + + /* 'self' is now off core */ + assert(thread == current_thread_volatile()); + + DTRACE_SCHED(on__cpu); + +#if KPERF + kperf_on_cpu(thread, continuation, NULL); +#endif /* KPERF */ + + thread_dispatch(self, thread); + +#if KASAN + /* Old thread's stack has been moved to the new thread, so explicitly + * unpoison it. */ + kasan_unpoison_stack(thread->kernel_stack, kernel_stack_size); +#endif + + thread->continuation = thread->parameter = NULL; + + counter(c_thread_invoke_hits++); + + assert(continuation); + call_continuation(continuation, parameter, thread->wait_result, TRUE); + /*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); + +#if KASAN + /* stack handoff to self - no thread_dispatch(), so clear the stack + * and free the fakestack directly */ + kasan_fakestack_drop(self); + kasan_fakestack_gc(self); + kasan_unpoison_stack(self->kernel_stack, kernel_stack_size); +#endif + + self->continuation = self->parameter = NULL; + + call_continuation(continuation, parameter, self->wait_result, TRUE); + /*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_state_update_from_thread(processor, thread); + + 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; + processor_timer_switch_thread(ctime, &thread->system_timer); + timer_update(&thread->runnable_timer, ctime); + 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_update(PROCESSOR_DATA(processor, current_state), ctime); + } + + 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); + +#if KPERF + kperf_off_cpu(self); +#endif /* KPERF */ + + /* + * 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_volatile()); + 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; + + call_continuation(continuation, parameter, self->wait_result, TRUE); + /*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)) { + uint64_t dispatching_map = (pset->cpu_state_map[PROCESSOR_DISPATCHING] & + pset->pending_deferred_AST_cpu_mask & + ~pset->pending_AST_cpu_mask); + for (int cpuid = lsb_first(dispatching_map); cpuid >= 0; cpuid = lsb_next(dispatching_map, cpuid)) { + active_processor = processor_array[cpuid]; + /* + * 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 != processor) { + /* + * Squash all of the processor state back to some + * reasonable facsimile of PROCESSOR_IDLE. + */ + + assert(active_processor->next_thread == THREAD_NULL); + processor_state_update_idle(active_processor); + active_processor->deadline = UINT64_MAX; + pset_update_processor_state(pset, active_processor, PROCESSOR_IDLE); + bit_clear(pset->pending_deferred_AST_cpu_mask, 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 + +static void +thread_csw_callout( + thread_t old, + thread_t new, + uint64_t timestamp) +{ + perfcontrol_event event = (new->state & TH_IDLE) ? IDLE : CONTEXT_SWITCH; + uint64_t same_pri_latency = (new->state & TH_IDLE) ? 0 : new->same_pri_latency; + machine_switch_perfcontrol_context(event, timestamp, 0, + same_pri_latency, old, new); +} + + +/* + * 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_volatile()); + assert(thread != self); + + if (thread != THREAD_NULL) { + /* + * Do the perfcontrol callout for context switch. + * The reason we do this here is: + * - thread_dispatch() is called from various places that are not + * the direct context switch path for eg. processor shutdown etc. + * So adding the callout here covers all those cases. + * - We want this callout as early as possible to be close + * to the timestamp taken in thread_invoke() + * - We want to avoid holding the thread lock while doing the + * callout + * - We do not want to callout if "thread" is NULL. + */ + thread_csw_callout(thread, self, processor->last_dispatch); + +#if KASAN + if (thread->continuation != NULL) { + /* + * Thread has a continuation and the normal stack is going away. + * Unpoison the stack and mark all fakestack objects as unused. + */ + kasan_fakestack_drop(thread); + if (thread->kernel_stack) { + kasan_unpoison_stack(thread->kernel_stack, kernel_stack_size); + } + } + + /* + * Free all unused fakestack objects. + */ + kasan_fakestack_gc(thread); +#endif + + /* + * 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(thread, thread->t_ledger, + task_ledgers.cpu_time, consumed); + ledger_credit_thread(thread, thread->t_threadledger, + thread_ledgers.cpu_time, consumed); + if (thread->t_bankledger) { + ledger_credit_thread(thread, thread->t_bankledger, + bank_ledgers.cpu_time, + (consumed - thread->t_deduct_bank_ledger_time)); + } + thread->t_deduct_bank_ledger_time = 0; + } + + 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 = thread->last_basepri_change_time = processor->last_dispatch; + + machine_thread_going_off_core(thread, FALSE, processor->last_dispatch); + + ast_t reason = thread->reason; + sched_options_t options = SCHED_NONE; + + if (reason & AST_REBALANCE) { + options |= SCHED_REBALANCE; + if (reason & AST_QUANTUM) { + /* + * Having gone to the trouble of forcing this thread off a less preferred core, + * we should force the preferable core to reschedule immediately to give this + * thread a chance to run instead of just sitting on the run queue where + * it may just be stolen back by the idle core we just forced it off. + * But only do this at the end of a quantum to prevent cascading effects. + */ + options |= SCHED_PREEMPT; + } + } + + if (reason & AST_QUANTUM) + options |= SCHED_TAILQ; + else if (reason & AST_PREEMPT) + options |= SCHED_HEADQ; + else + options |= (SCHED_PREEMPT | SCHED_TAILQ); + + thread_setrun(thread, options); + + 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; + int thread_state = thread->state; + + /* 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; + } + + timer_stop(&thread->runnable_timer, processor->last_dispatch); + + thread_state &= ~TH_RUN; + thread->state = thread_state; + + thread->last_made_runnable_time = thread->last_basepri_change_time = THREAD_NOT_RUNNABLE; + thread->chosen_processor = PROCESSOR_NULL; + + new_run_count = sched_run_decr(thread); + +#if CONFIG_SCHED_SFI + if (thread->reason & AST_SFI) { + thread->wait_sfi_begin_time = processor->last_dispatch; + } +#endif + + machine_thread_going_off_core(thread, should_terminate, processor->last_dispatch); + + 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); + + if (thread_state & TH_WAIT_REPORT) { + (*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); + } + } + } + + int urgency = THREAD_URGENCY_NONE; + uint64_t latency = 0; + + /* Update (new) current thread and reprogram quantum timer */ + thread_lock(self); + + if (!(self->state & TH_IDLE)) { + uint64_t arg1, arg2; + +#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); + + assert(self->last_made_runnable_time <= self->last_basepri_change_time); + + latency = processor->last_dispatch - self->last_made_runnable_time; + assert(latency >= self->same_pri_latency); + + urgency = thread_get_urgency(self, &arg1, &arg2); + + thread_tell_urgency(urgency, arg1, arg2, latency, self); + + /* + * 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_quantum_timer_enter(&processor->quantum_timer, self, + processor->quantum_end, processor->last_dispatch); + + processor->first_timeslice = TRUE; + } else { + timer_call_quantum_timer_cancel(&processor->quantum_timer); + processor->first_timeslice = FALSE; + + thread_tell_urgency(THREAD_URGENCY_NONE, 0, 0, 0, self); + } + + assert(self->block_hint == kThreadWaitNone); + self->computation_epoch = processor->last_dispatch; + self->reason = AST_NONE; + processor->starting_pri = self->sched_pri; + + thread_unlock(self); + + machine_thread_going_on_core(self, urgency, latency, self->same_pri_latency, + processor->last_dispatch); + +#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 reason = AST_HANDOFF; + + self->continuation = continuation; + self->parameter = parameter; + + while (!thread_invoke(self, new_thread, reason)) { + /* the handoff failed, so we have to fall back to the normal block path */ + processor_t processor = current_processor(); + + reason = AST_NONE; + + thread_lock(self); + new_thread = thread_select(self, processor, &reason); + thread_unlock(self); + } + + 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 INTERRUPT_MASKED_DEBUG + /* Reset interrupt-masked spin debugging timeout */ + ml_spin_debug_clear(self); +#endif + + TLOG(1, "thread_continue: calling call_continuation\n"); + + boolean_t enable_interrupts = thread != THREAD_NULL; + call_continuation(continuation, parameter, self->wait_result, enable_interrupts); + /*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 +sched_rtglobal_runq_scan(sched_update_scan_context_t scan_context) +{ + spl_t s; + thread_t thread; + + processor_set_t pset = &pset0; + + s = splsched(); + rt_lock_lock(pset); + + qe_foreach_element_safe(thread, &pset->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(pset); + splx(s); +} + +int64_t +sched_rtglobal_runq_count_sum(void) +{ + return pset0.rt_runq.runq_stats.count_sum; +} + +/* + * realtime_queue_insert: + * + * Enqueue a thread for realtime execution. + */ +static boolean_t +realtime_queue_insert(processor_t processor, processor_set_t pset, thread_t thread) +{ + queue_t queue = &SCHED(rt_runq)(pset)->queue; + uint64_t deadline = thread->realtime.deadline; + boolean_t preempt = FALSE; + + rt_lock_lock(pset); + + 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 = processor; + SCHED_STATS_RUNQ_CHANGE(&SCHED(rt_runq)(pset)->runq_stats, rt_runq_count(pset)); + rt_runq_count_incr(pset); + + rt_lock_unlock(pset); + + 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; + pset_assert_locked(pset); + ast_t preempt; + + sched_ipi_type_t ipi_type = SCHED_IPI_NONE; + + thread->chosen_processor = processor; + + /* */ + assert(thread->bound_processor == PROCESSOR_NULL); + + /* + * Dispatch directly onto idle processor. + */ + if ( (thread->bound_processor == processor) + && processor->state == PROCESSOR_IDLE) { + + processor->next_thread = thread; + processor_state_update_from_thread(processor, thread); + processor->deadline = thread->realtime.deadline; + pset_update_processor_state(pset, processor, PROCESSOR_DISPATCHING); + + ipi_type = sched_ipi_action(processor, thread, true, SCHED_IPI_EVENT_BOUND_THR); + pset_unlock(pset); + sched_ipi_perform(processor, ipi_type); + 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(processor, pset, thread); + + ipi_type = SCHED_IPI_NONE; + if (preempt != AST_NONE) { + if (processor->state == PROCESSOR_IDLE) { + processor->next_thread = THREAD_NULL; + processor_state_update_from_thread(processor, thread); + processor->deadline = thread->realtime.deadline; + pset_update_processor_state(pset, processor, PROCESSOR_DISPATCHING); + if (processor == current_processor()) { + ast_on(preempt); + } else { + ipi_type = sched_ipi_action(processor, thread, true, SCHED_IPI_EVENT_PREEMPT); + } + } else if (processor->state == PROCESSOR_DISPATCHING) { + if ((processor->next_thread == THREAD_NULL) && ((processor->current_pri < thread->sched_pri) || (processor->deadline > thread->realtime.deadline))) { + processor_state_update_from_thread(processor, thread); + processor->deadline = thread->realtime.deadline; + } + } else { + if (processor == current_processor()) { + ast_on(preempt); + } else { + ipi_type = sched_ipi_action(processor, thread, false, SCHED_IPI_EVENT_PREEMPT); + } + } + } else { + /* Selected processor was too busy, just keep thread enqueued and let other processors drain it naturally. */ + } + + pset_unlock(pset); + sched_ipi_perform(processor, ipi_type); +} + + +sched_ipi_type_t sched_ipi_deferred_policy(processor_set_t pset, processor_t dst, + __unused sched_ipi_event_t event) +{ +#if defined(CONFIG_SCHED_DEFERRED_AST) + if (!bit_test(pset->pending_deferred_AST_cpu_mask, dst->cpu_id)) { + return SCHED_IPI_DEFERRED; + } +#else /* CONFIG_SCHED_DEFERRED_AST */ + panic("Request for deferred IPI on an unsupported platform; pset: %p CPU: %d", pset, dst->cpu_id); +#endif /* CONFIG_SCHED_DEFERRED_AST */ + return SCHED_IPI_NONE; +} + +sched_ipi_type_t sched_ipi_action(processor_t dst, thread_t thread, boolean_t dst_idle, sched_ipi_event_t event) +{ + sched_ipi_type_t ipi_type = SCHED_IPI_NONE; + assert(dst != NULL); + + processor_set_t pset = dst->processor_set; + if (current_processor() == dst) { + return SCHED_IPI_NONE; + } + + if (bit_test(pset->pending_AST_cpu_mask, dst->cpu_id)) { + return SCHED_IPI_NONE; + } + + ipi_type = SCHED(ipi_policy)(dst, thread, dst_idle, event); + switch(ipi_type) { + case SCHED_IPI_NONE: + return SCHED_IPI_NONE; +#if defined(CONFIG_SCHED_DEFERRED_AST) + case SCHED_IPI_DEFERRED: + bit_set(pset->pending_deferred_AST_cpu_mask, dst->cpu_id); + break; +#endif /* CONFIG_SCHED_DEFERRED_AST */ + default: + bit_set(pset->pending_AST_cpu_mask, dst->cpu_id); + break; + } + return ipi_type; +} + +sched_ipi_type_t sched_ipi_policy(processor_t dst, thread_t thread, boolean_t dst_idle, sched_ipi_event_t event) +{ + sched_ipi_type_t ipi_type = SCHED_IPI_NONE; + boolean_t deferred_ipi_supported = false; + processor_set_t pset = dst->processor_set; + +#if defined(CONFIG_SCHED_DEFERRED_AST) + deferred_ipi_supported = true; +#endif /* CONFIG_SCHED_DEFERRED_AST */ + + switch(event) { + case SCHED_IPI_EVENT_SPILL: + case SCHED_IPI_EVENT_SMT_REBAL: + case SCHED_IPI_EVENT_REBALANCE: + case SCHED_IPI_EVENT_BOUND_THR: + /* + * The spill, SMT rebalance, rebalance and the bound thread + * scenarios use immediate IPIs always. + */ + ipi_type = dst_idle ? SCHED_IPI_IDLE : SCHED_IPI_IMMEDIATE; + break; + case SCHED_IPI_EVENT_PREEMPT: + /* In the preemption case, use immediate IPIs for RT threads */ + if (thread && (thread->sched_pri >= BASEPRI_RTQUEUES)) { + ipi_type = dst_idle ? SCHED_IPI_IDLE : SCHED_IPI_IMMEDIATE; + break; + } + + /* + * For Non-RT threads preemption, + * If the core is active, use immediate IPIs. + * If the core is idle, use deferred IPIs if supported; otherwise immediate IPI. + */ + if (deferred_ipi_supported && dst_idle) { + return sched_ipi_deferred_policy(pset, dst, event); + } + ipi_type = dst_idle ? SCHED_IPI_IDLE : SCHED_IPI_IMMEDIATE; + break; + default: + panic("Unrecognized scheduler IPI event type %d", event); + } + assert(ipi_type != SCHED_IPI_NONE); + return ipi_type; +} + +void sched_ipi_perform(processor_t dst, sched_ipi_type_t ipi) +{ + switch (ipi) { + case SCHED_IPI_NONE: + break; + case SCHED_IPI_IDLE: + machine_signal_idle(dst); + break; + case SCHED_IPI_IMMEDIATE: + cause_ast_check(dst); + break; + case SCHED_IPI_DEFERRED: + machine_signal_idle_deferred(dst); + break; + default: + panic("Unrecognized scheduler IPI type: %d", ipi); + } +} + +#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; + pset_assert_locked(pset); + ast_t preempt; + enum { eExitIdle, eInterruptRunning, eDoNothing } ipi_action = eDoNothing; + + sched_ipi_type_t ipi_type = SCHED_IPI_NONE; + + thread->chosen_processor = processor; + + /* + * Dispatch directly onto idle processor. + */ + if ( (SCHED(direct_dispatch_to_idle_processors) || + thread->bound_processor == processor) + && processor->state == PROCESSOR_IDLE) { + + processor->next_thread = thread; + processor_state_update_from_thread(processor, thread); + processor->deadline = UINT64_MAX; + pset_update_processor_state(pset, processor, PROCESSOR_DISPATCHING); + + ipi_type = sched_ipi_action(processor, thread, true, SCHED_IPI_EVENT_BOUND_THR); + pset_unlock(pset); + sched_ipi_perform(processor, ipi_type); + 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; + + if ((options & (SCHED_PREEMPT|SCHED_REBALANCE)) == (SCHED_PREEMPT|SCHED_REBALANCE)) { + /* + * Having gone to the trouble of forcing this thread off a less preferred core, + * we should force the preferable core to reschedule immediately to give this + * thread a chance to run instead of just sitting on the run queue where + * it may just be stolen back by the idle core we just forced it off. + */ + preempt |= AST_PREEMPT; + } + + SCHED(processor_enqueue)(processor, thread, options); + sched_update_pset_load_average(pset); + + if (preempt != AST_NONE) { + if (processor->state == PROCESSOR_IDLE) { + processor->next_thread = THREAD_NULL; + processor_state_update_from_thread(processor, thread); + processor->deadline = UINT64_MAX; + pset_update_processor_state(pset, processor, PROCESSOR_DISPATCHING); + ipi_action = eExitIdle; + } else if ( processor->state == PROCESSOR_DISPATCHING) { + if ((processor->next_thread == THREAD_NULL) && (processor->current_pri < thread->sched_pri)) { + processor_state_update_from_thread(processor, thread); + 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->next_thread = THREAD_NULL; + processor_state_update_from_thread(processor, thread); + processor->deadline = UINT64_MAX; + pset_update_processor_state(pset, processor, PROCESSOR_DISPATCHING); + + ipi_action = eExitIdle; + } + } + + if (ipi_action != eDoNothing) { + if (processor == current_processor()) { + if (csw_check_locked(processor, pset, AST_NONE) != AST_NONE) + ast_on(preempt); + } else { + sched_ipi_event_t event = (options & SCHED_REBALANCE) ? SCHED_IPI_EVENT_REBALANCE : SCHED_IPI_EVENT_PREEMPT; + ipi_type = sched_ipi_action(processor, thread, (ipi_action == eExitIdle), event); + } + } + pset_unlock(pset); + sched_ipi_perform(processor, ipi_type); +} + +/* + * 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 starting_pset, + processor_t processor, + thread_t thread) +{ + processor_set_t pset = starting_pset; + processor_set_t nset; + + 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_secondary_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 lp_paired_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 + */ + + uint64_t idle_primary_map = (pset->cpu_state_map[PROCESSOR_IDLE] & + pset->primary_map & + pset->recommended_bitmask & + ~pset->pending_AST_cpu_mask); + + int cpuid = lsb_first(idle_primary_map); + if (cpuid >= 0) { + processor = processor_array[cpuid]; + return processor; + } + + /* + * Otherwise, enumerate active and idle processors to find primary candidates + * with lower priority/etc. + */ + + uint64_t active_map = ((pset->cpu_state_map[PROCESSOR_RUNNING] | pset->cpu_state_map[PROCESSOR_DISPATCHING]) & + pset->recommended_bitmask & + ~pset->pending_AST_cpu_mask); + active_map = bit_ror64(active_map, (pset->last_chosen + 1)); + for (int rotid = lsb_first(active_map); rotid >= 0; rotid = lsb_next(active_map, rotid)) { + cpuid = ((rotid + pset->last_chosen + 1) & 63); + processor = processor_array[cpuid]; + + integer_t cpri = processor->current_pri; + if (processor->processor_primary != processor) { + if (cpri < lowest_secondary_priority) { + lowest_secondary_priority = cpri; + lp_paired_secondary_processor = processor; + } + } else { + if (cpri < lowest_priority) { + lowest_priority = cpri; + lp_processor = processor; + } + } + + if ((cpri >= BASEPRI_RTQUEUES) && (processor->deadline > furthest_deadline)) { + furthest_deadline = processor->deadline; + fd_processor = processor; + } + + integer_t ccount = SCHED(processor_runq_count)(processor); + if (ccount < lowest_count) { + lowest_count = ccount; + lc_processor = processor; + } + } + + /* + * For SMT configs, these idle secondary processors must have active primary. Otherwise + * the idle primary would have short-circuited the loop above + */ + uint64_t idle_secondary_map = (pset->cpu_state_map[PROCESSOR_IDLE] & + ~pset->primary_map & + pset->recommended_bitmask & + ~pset->pending_AST_cpu_mask); + + for (cpuid = lsb_first(idle_secondary_map); cpuid >= 0; cpuid = lsb_next(idle_secondary_map, cpuid)) { + processor = processor_array[cpuid]; + + processor_t cprimary = processor->processor_primary; + + if (!cprimary->is_recommended) { + continue; + } + if (bit_test(pset->pending_AST_cpu_mask, cprimary->cpu_id)) { + continue; + } + + /* If the primary processor is offline or starting up, it's not a candidate for this path */ + if (cprimary->state == PROCESSOR_RUNNING || cprimary->state == PROCESSOR_DISPATCHING) { + integer_t primary_pri = cprimary->current_pri; + + if (primary_pri < lowest_unpaired_primary_priority) { + lowest_unpaired_primary_priority = primary_pri; + lp_unpaired_primary_processor = cprimary; + lp_unpaired_secondary_processor = processor; + } + } + } + + + if (thread->sched_pri >= BASEPRI_RTQUEUES) { + + /* + * For realtime threads, the most important aspect is + * scheduling latency, so we attempt to assign threads + * to good preemption candidates (assuming an idle primary + * processor was not available above). + */ + + if (thread->sched_pri > lowest_unpaired_primary_priority) { + pset->last_chosen = lp_unpaired_primary_processor->cpu_id; + return lp_unpaired_primary_processor; + } + if (thread->sched_pri > lowest_priority) { + pset->last_chosen = lp_processor->cpu_id; + return lp_processor; + } + if (sched_allow_rt_smt && (thread->sched_pri > lowest_secondary_priority)) { + pset->last_chosen = lp_paired_secondary_processor->cpu_id; + return lp_paired_secondary_processor; + } + if (thread->realtime.deadline < furthest_deadline) + return fd_processor; + + /* + * If all primary and secondary CPUs are busy with realtime + * threads with deadlines earlier than us, move on to next + * pset. + */ + } + else { + + if (thread->sched_pri > lowest_unpaired_primary_priority) { + pset->last_chosen = lp_unpaired_primary_processor->cpu_id; + return lp_unpaired_primary_processor; + } + if (thread->sched_pri > lowest_priority) { + pset->last_chosen = lp_processor->cpu_id; + return lp_processor; + } + + /* + * 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. + */ + } + + /* + * Move onto the next processor set. + */ + nset = next_pset(pset); + + if (nset != starting_pset) { + pset_unlock(pset); + + pset = nset; + pset_lock(pset); + } + } while (nset != starting_pset); + + /* + * 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 { + + /* 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 (lp_paired_secondary_processor != PROCESSOR_NULL) { + processor = lp_paired_secondary_processor; + lp_paired_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; + } + + /* + * Check that the correct processor set is + * returned locked. + */ + if (pset != processor->processor_set) { + pset_unlock(pset); + pset = processor->processor_set; + pset_lock(pset); + } + + /* + * 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); + + pset->last_chosen = processor->cpu_id; + return processor; +} + +/* + * thread_setrun: + * + * Dispatch thread for execution, onto an idle + * processor or run queue, and signal a preemption + * as appropriate. + * + * Thread must be locked. + */ +void +thread_setrun( + thread_t thread, + integer_t options) +{ + 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); + + /* + * Update priority if needed. + */ + if (SCHED(can_update_priority)(thread)) + SCHED(update_priority)(thread); + + thread->sfi_class = sfi_thread_classify(thread); + + assert(thread->runq == PROCESSOR_NULL); + +#if __SMP__ + if (thread->bound_processor == PROCESSOR_NULL) { + /* + * Unbound case. + */ + if (thread->affinity_set != AFFINITY_SET_NULL) { + /* + * Use affinity set policy hint. + */ + pset = thread->affinity_set->aset_pset; + pset_lock(pset); + + processor = SCHED(choose_processor)(pset, PROCESSOR_NULL, thread); + pset = processor->processor_set; + + SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHOOSE_PROCESSOR)|DBG_FUNC_NONE, + (uintptr_t)thread_tid(thread), (uintptr_t)-1, processor->cpu_id, processor->state, 0); + } else if (thread->last_processor != PROCESSOR_NULL) { + /* + * Simple (last processor) affinity case. + */ + processor = thread->last_processor; + pset = processor->processor_set; + pset_lock(pset); + processor = SCHED(choose_processor)(pset, processor, thread); + pset = processor->processor_set; + + SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHOOSE_PROCESSOR)|DBG_FUNC_NONE, + (uintptr_t)thread_tid(thread), thread->last_processor->cpu_id, processor->cpu_id, processor->state, 0); + } else { + /* + * No Affinity case: + * + * Utilitize a per task hint to spread threads + * among the available processor sets. + */ + task_t task = thread->task; + + pset = task->pset_hint; + if (pset == PROCESSOR_SET_NULL) + pset = current_processor()->processor_set; + + pset = choose_next_pset(pset); + pset_lock(pset); + + processor = SCHED(choose_processor)(pset, PROCESSOR_NULL, thread); + pset = processor->processor_set; + task->pset_hint = pset; + + SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHOOSE_PROCESSOR)|DBG_FUNC_NONE, + (uintptr_t)thread_tid(thread), (uintptr_t)-1, processor->cpu_id, processor->state, 0); + } + } else { + /* + * Bound case: + * + * Unconditionally dispatch on the processor. + */ + processor = thread->bound_processor; + pset = processor->processor_set; + pset_lock(pset); + + SCHED_DEBUG_CHOOSE_PROCESSOR_KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHOOSE_PROCESSOR)|DBG_FUNC_NONE, + (uintptr_t)thread_tid(thread), (uintptr_t)-2, processor->cpu_id, processor->state, 0); + } +#else /* !__SMP__ */ + /* Only one processor to choose */ + assert(thread->bound_processor == PROCESSOR_NULL || thread->bound_processor == master_processor); + processor = master_processor; + pset = processor->processor_set; + pset_lock(pset); +#endif /* !__SMP__ */ + + /* + * Dispatch the thread on the 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); + } + /* pset is now unlocked */ + if (thread->bound_processor == PROCESSOR_NULL) { + SCHED(check_spill)(pset, thread); + } +} + +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 preemption point in + * the current context. + * + * Called at splsched with thread locked. + */ +ast_t +csw_check( + processor_t processor, + ast_t check_reason) +{ + processor_set_t pset = processor->processor_set; + ast_t result; + + pset_lock(pset); + + /* If we were sent a remote AST and interrupted a running processor, acknowledge it here with pset lock held */ + bit_clear(pset->pending_AST_cpu_mask, processor->cpu_id); + + result = csw_check_locked(processor, pset, check_reason); + + pset_unlock(pset); + + return result; +} + +/* + * Check for preemption at splsched with + * pset and thread locked + */ +ast_t +csw_check_locked( + processor_t processor, + processor_set_t pset, + ast_t check_reason) +{ + ast_t result; + thread_t thread = processor->active_thread; + + if (processor->first_timeslice) { + if (rt_runq_count(pset) > 0) + return (check_reason | AST_PREEMPT | AST_URGENT); + } + else { + if (rt_runq_count(pset) > 0) { + if (BASEPRI_RTQUEUES > processor->current_pri) + return (check_reason | AST_PREEMPT | AST_URGENT); + else + return (check_reason | AST_PREEMPT); + } + } + +#if __SMP__ + /* + * If the current thread is running on a processor that is no longer recommended, + * urgently preempt it, at 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 | AST_URGENT); + } +#endif + + result = SCHED(processor_csw_check)(processor); + if (result != AST_NONE) + return (check_reason | result | (thread_eager_preemption(thread) ? AST_URGENT : AST_NONE)); + +#if __SMP__ + /* + * Same for avoid-processor + * + * TODO: Should these set AST_REBALANCE? + */ + if (SCHED(avoid_processor_enabled) && SCHED(thread_avoid_processor)(processor, thread)) { + 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 + */ + + if (processor->current_pri < BASEPRI_RTQUEUES && + processor->processor_primary != processor) + return (check_reason | AST_PREEMPT); +#endif + + if (thread->state & TH_SUSP) + return (check_reason | AST_PREEMPT); + +#if CONFIG_SCHED_SFI + /* + * Current thread may not need to be preempted, but maybe needs + * an SFI wait? + */ + result = sfi_thread_needs_ast(thread, NULL); + if (result != AST_NONE) + return (check_reason | result); +#endif + + return (AST_NONE); +} + +/* + * set_sched_pri: + * + * Set the scheduled priority of the specified thread. + * + * This may cause the thread to change queues. + * + * Thread must be locked. + */ +void +set_sched_pri( + thread_t thread, + int new_priority, + set_sched_pri_options_t options) +{ + 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; - myprocessor->current_pri = thread->sched_pri; + bool lazy_update = ((options & SETPRI_LAZY) == SETPRI_LAZY); - simple_lock(&runq->lock); - simple_lock(&pset->runq.lock); + int old_priority = thread->sched_pri; - other_runnable = runq->count > 0 || pset->runq.count > 0; + /* If we're already at this priority, no need to mess with the runqueue */ + if (new_priority == old_priority) + return; - if ( thread->state == TH_RUN && - (!other_runnable || - (runq->highq < thread->sched_pri && - pset->runq.highq < thread->sched_pri)) && - thread->processor_set == pset && - (thread->bound_processor == PROCESSOR_NULL || - thread->bound_processor == myprocessor) ) { + 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); + } - /* I am the highest priority runnable (non-idle) thread */ - simple_unlock(&pset->runq.lock); - simple_unlock(&runq->lock); + thread->sched_pri = new_priority; - myprocessor->slice_quanta = - (thread->sched_mode & TH_MODE_TIMESHARE)? pset->set_quanta: 1; - } - else - if (other_runnable) - thread = choose_thread(myprocessor); - else { - simple_unlock(&pset->runq.lock); - simple_unlock(&runq->lock); + KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHANGE_PRIORITY), + (uintptr_t)thread_tid(thread), + thread->base_pri, + thread->sched_pri, + thread->sched_usage, + 0); + if (is_current_thread) { + nurgency = thread_get_urgency(thread, &urgency_param1, &urgency_param2); /* - * Nothing is runnable, so set this processor idle if it - * was running. If it was in an assignment or shutdown, - * leave it alone. Return its idle thread. + * 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. */ - simple_lock(&pset->sched_lock); - if (myprocessor->state == PROCESSOR_RUNNING) { - remqueue(&pset->active_queue, (queue_entry_t)myprocessor); - myprocessor->state = PROCESSOR_IDLE; + uint64_t ctime = mach_approximate_time(); + if (nurgency != curgency) { + thread_tell_urgency(nurgency, urgency_param1, urgency_param2, 0, thread); + } + machine_thread_going_on_core(thread, nurgency, 0, 0, ctime); + } - if (myprocessor == master_processor) - enqueue_tail(&pset->idle_queue, (queue_entry_t)myprocessor); - else - enqueue_head(&pset->idle_queue, (queue_entry_t)myprocessor); + 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; - pset->idle_count++; - } - simple_unlock(&pset->sched_lock); + if (is_current_thread) { + processor_state_update_from_thread(processor, thread); - thread = myprocessor->idle_thread; - } + /* + * When dropping in priority, check if the thread no longer belongs on core. + * If a thread raises its own priority, don't aggressively rebalance it. + * + */ + if (!lazy_update && new_priority < old_priority) { + ast_t preempt; - return (thread); + if ((preempt = csw_check(processor, AST_NONE)) != AST_NONE) + ast_on(preempt); + } + } else if (!lazy_update && processor != PROCESSOR_NULL && + processor != current_processor() && processor->active_thread == thread) { + cause_ast_check(processor); + } + } } - /* - * Stop running the current thread and start running the new thread. - * If continuation is non-zero, and the current thread is blocked, - * then it will resume by executing continuation on a new stack. - * Returns TRUE if the hand-off succeeds. + * thread_run_queue_remove_for_handoff * - * Assumes splsched. + * Pull a thread or its (recursive) push target out of the runqueue + * so that it is ready for thread_run() + * + * Called at splsched + * + * Returns the thread that was pulled or THREAD_NULL if no thread could be pulled. + * This may be different than the thread that was passed in. */ +thread_t +thread_run_queue_remove_for_handoff(thread_t thread) { -static thread_t -__current_thread(void) -{ - return (current_thread()); -} - -boolean_t -thread_invoke( - register thread_t old_thread, - register thread_t new_thread, - int reason, - thread_continue_t old_cont) -{ - thread_continue_t new_cont; - processor_t processor; + thread_t pulled_thread = THREAD_NULL; - if (get_preemption_level() != 0) - panic("thread_invoke: preemption_level %d\n", - get_preemption_level()); + thread_lock(thread); /* - * Mark thread interruptible. + * 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. */ - thread_lock(new_thread); - new_thread->state &= ~TH_UNINT; - assert(thread_runnable(new_thread)); + 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)) { - assert(old_thread->continuation == NULL); - - /* - * Allow time constraint threads to hang onto - * a stack. - */ - if ( (old_thread->sched_mode & TH_MODE_REALTIME) && - !old_thread->stack_privilege ) { - old_thread->stack_privilege = old_thread->kernel_stack; + if (thread_run_queue_remove(thread)) + pulled_thread = thread; } - if (old_cont != NULL) { - if (new_thread->state & TH_STACK_HANDOFF) { - /* - * If the old thread is using a privileged stack, - * check to see whether we can exchange it with - * that of the new thread. - */ - if ( old_thread->kernel_stack == old_thread->stack_privilege && - !new_thread->stack_privilege) - goto need_stack; + thread_unlock(thread); - new_thread->state &= ~TH_STACK_HANDOFF; - new_cont = new_thread->continuation; - new_thread->continuation = NULL; + return pulled_thread; +} - /* - * Set up ast context of new thread and switch - * to its timer. - */ - processor = current_processor(); - new_thread->last_processor = processor; - processor->current_pri = new_thread->sched_pri; - ast_context(new_thread->top_act, processor->slot_num); - timer_switch(&new_thread->system_timer); - thread_unlock(new_thread); - - current_task()->csw++; +/* + * thread_run_queue_remove: + * + * Remove a thread from its current run queue and + * return TRUE if successful. + * + * Thread must be locked. + * + * If thread->runq is PROCESSOR_NULL, the thread will not re-enter the + * run queues because the caller locked the thread. Otherwise + * the thread is on a run queue, but could be chosen for dispatch + * and removed by another processor under a different lock, which + * will set thread->runq to PROCESSOR_NULL. + * + * Hence the thread select path must not rely on anything that could + * be changed under the thread lock after calling this function, + * most importantly thread->sched_pri. + */ +boolean_t +thread_run_queue_remove( + thread_t thread) +{ + boolean_t removed = FALSE; + processor_t processor = thread->runq; - old_thread->reason = reason; - old_thread->continuation = old_cont; - - _mk_sp_thread_done(old_thread, new_thread, processor); + if ((thread->state & (TH_RUN|TH_WAIT)) == TH_WAIT) { + /* Thread isn't runnable */ + assert(thread->runq == PROCESSOR_NULL); + return FALSE; + } - stack_handoff(old_thread, new_thread); + 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. + */ - _mk_sp_thread_begin(new_thread, processor); + return FALSE; + } - wake_lock(old_thread); - thread_lock(old_thread); + if (thread->sched_pri < BASEPRI_RTQUEUES) { + return SCHED(processor_queue_remove)(processor, thread); + } - /* - * Inline thread_dispatch but - * don't free stack. - */ + processor_set_t pset = processor->processor_set; - switch (old_thread->state & (TH_RUN|TH_WAIT|TH_UNINT|TH_IDLE)) { - - case TH_RUN | TH_UNINT: - case TH_RUN: - /* - * Still running, put back - * onto a run queue. - */ - old_thread->state |= TH_STACK_HANDOFF; - _mk_sp_thread_dispatch(old_thread); + rt_lock_lock(pset); - thread_unlock(old_thread); - wake_unlock(old_thread); - break; + if (thread->runq != PROCESSOR_NULL) { + /* + * Thread is on the RT run queue and we have a lock on + * that run queue. + */ - case TH_RUN | TH_WAIT | TH_UNINT: - case TH_RUN | TH_WAIT: - { - boolean_t reap, wake, callblock; + remqueue(&thread->runq_links); + SCHED_STATS_RUNQ_CHANGE(&SCHED(rt_runq)(pset)->runq_stats, rt_runq_count(pset)); + rt_runq_count_decr(pset); - /* - * Waiting. - */ - old_thread->sleep_stamp = sched_tick; - old_thread->state |= TH_STACK_HANDOFF; - old_thread->state &= ~TH_RUN; - hw_atomic_sub(&old_thread->processor_set->run_count, 1); - callblock = old_thread->active_callout; - wake = old_thread->wake_active; - old_thread->wake_active = FALSE; - reap = (old_thread->state & TH_TERMINATE)? TRUE: FALSE; - - thread_unlock(old_thread); - wake_unlock(old_thread); - - if (callblock) - call_thread_block(); - - if (wake) - thread_wakeup((event_t)&old_thread->wake_active); - - if (reap) - thread_reaper_enqueue(old_thread); - break; - } + thread->runq = PROCESSOR_NULL; - case TH_RUN | TH_IDLE: - /* - * The idle threads don't go - * onto a run queue. - */ - old_thread->state |= TH_STACK_HANDOFF; - thread_unlock(old_thread); - wake_unlock(old_thread); - break; + removed = TRUE; + } - default: - panic("thread_invoke: state 0x%x\n", old_thread->state); - } + rt_lock_unlock(pset); - counter_always(c_thread_invoke_hits++); + return (removed); +} - if (new_thread->funnel_state & TH_FN_REFUNNEL) { - kern_return_t wait_result = new_thread->wait_result; +/* + * 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) +{ + assert(thread->runq == PROCESSOR_NULL); + assert(thread->state & (TH_RUN)); - new_thread->funnel_state = 0; - KERNEL_DEBUG(0x6032428 | DBG_FUNC_NONE, - new_thread->funnel_lock, 2, 0, 0, 0); - funnel_lock(new_thread->funnel_lock); - KERNEL_DEBUG(0x6032430 | DBG_FUNC_NONE, - new_thread->funnel_lock, 2, 0, 0, 0); - new_thread->funnel_state = TH_FN_OWNED; - new_thread->wait_result = wait_result; - } - (void) spllo(); + thread_setrun(thread, options); +} - assert(new_cont); - call_continuation(new_cont); - /*NOTREACHED*/ - return (TRUE); - } - else - if (new_thread->state & TH_STACK_ALLOC) { - /* - * Waiting for a stack - */ - counter_always(c_thread_invoke_misses++); - thread_unlock(new_thread); - return (FALSE); - } - else - if (new_thread == old_thread) { - /* same thread but with continuation */ - counter(++c_thread_invoke_same); - thread_unlock(new_thread); +void +sys_override_cpu_throttle(boolean_t enable_override) +{ + if (enable_override) + cpu_throttle_enabled = 0; + else + cpu_throttle_enabled = 1; +} - if (new_thread->funnel_state & TH_FN_REFUNNEL) { - kern_return_t wait_result = new_thread->wait_result; - - new_thread->funnel_state = 0; - KERNEL_DEBUG(0x6032428 | DBG_FUNC_NONE, - new_thread->funnel_lock, 3, 0, 0, 0); - funnel_lock(new_thread->funnel_lock); - KERNEL_DEBUG(0x6032430 | DBG_FUNC_NONE, - new_thread->funnel_lock, 3, 0, 0, 0); - new_thread->funnel_state = TH_FN_OWNED; - new_thread->wait_result = wait_result; - } - (void) spllo(); - call_continuation(old_cont); - /*NOTREACHED*/ - } - } - else { +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))) { /* - * Check that the new thread has a stack + * Background urgency applied when thread priority is MAXPRI_THROTTLE or lower and thread is not promoted */ - if (new_thread->state & TH_STACK_HANDOFF) { -need_stack: - if (!stack_alloc_try(new_thread, thread_continue)) { - counter_always(c_thread_invoke_misses++); - thread_swapin(new_thread); - return (FALSE); - } - - new_thread->state &= ~TH_STACK_HANDOFF; - } - else - if (new_thread->state & TH_STACK_ALLOC) { - /* - * Waiting for a stack - */ - counter_always(c_thread_invoke_misses++); - thread_unlock(new_thread); - return (FALSE); - } - else - if (old_thread == new_thread) { - counter(++c_thread_invoke_same); - thread_unlock(new_thread); - return (TRUE); - } - } - - /* - * Set up ast context of new thread and switch to its timer. - */ - processor = current_processor(); - new_thread->last_processor = processor; - processor->current_pri = new_thread->sched_pri; - ast_context(new_thread->top_act, processor->slot_num); - timer_switch(&new_thread->system_timer); - 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; - old_thread->continuation = old_cont; - - _mk_sp_thread_done(old_thread, new_thread, processor); - - /* - * switch_context is machine-dependent. It does the - * machine-dependent components of a context-switch, like - * changing address spaces. It updates active_threads. - */ - old_thread = switch_context(old_thread, old_cont, new_thread); - - /* Now on new thread's stack. Set a local variable to refer to it. */ - new_thread = __current_thread(); - assert(old_thread != new_thread); + *arg1 = thread->sched_pri; + *arg2 = thread->base_pri; - assert(thread_runnable(new_thread)); - _mk_sp_thread_begin(new_thread, new_thread->last_processor); + 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); - /* - * We're back. Now old_thread is the thread that resumed - * us, and we have to dispatch it. - */ - thread_dispatch(old_thread); - - if (old_cont) { - if (new_thread->funnel_state & TH_FN_REFUNNEL) { - kern_return_t wait_result = new_thread->wait_result; - - new_thread->funnel_state = 0; - KERNEL_DEBUG(0x6032428 | DBG_FUNC_NONE, - new_thread->funnel_lock, 3, 0, 0, 0); - funnel_lock(new_thread->funnel_lock); - KERNEL_DEBUG(0x6032430 | DBG_FUNC_NONE, - new_thread->funnel_lock, 3, 0, 0, 0); - new_thread->funnel_state = TH_FN_OWNED; - new_thread->wait_result = wait_result; - } - (void) spllo(); - call_continuation(old_cont); - /*NOTREACHED*/ + return (THREAD_URGENCY_NORMAL); } +} - return (TRUE); +perfcontrol_class_t +thread_get_perfcontrol_class(thread_t thread) +{ + /* Special case handling */ + if (thread->state & TH_IDLE) + return PERFCONTROL_CLASS_IDLE; + if (thread->task == kernel_task) + return PERFCONTROL_CLASS_KERNEL; + if (thread->sched_mode == TH_MODE_REALTIME) + return PERFCONTROL_CLASS_REALTIME; + + /* perfcontrol_class based on base_pri */ + if (thread->base_pri <= MAXPRI_THROTTLE) + return PERFCONTROL_CLASS_BACKGROUND; + else if (thread->base_pri <= BASEPRI_UTILITY) + return PERFCONTROL_CLASS_UTILITY; + else if (thread->base_pri <= BASEPRI_DEFAULT) + return PERFCONTROL_CLASS_NONUI; + else if (thread->base_pri <= BASEPRI_FOREGROUND) + return PERFCONTROL_CLASS_UI; + else + return PERFCONTROL_CLASS_ABOVEUI; } /* - * thread_continue: + * 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. * - * Called when a thread gets a new stack, at splsched(); + * Returns a the next thread to execute if dispatched directly. */ -void -thread_continue( - register thread_t old_thread) -{ - register thread_t self = current_thread(); - register thread_continue_t continuation; - - continuation = self->continuation; - self->continuation = NULL; - _mk_sp_thread_begin(self, self->last_processor); - - /* - * We must dispatch the old thread and then - * call the current thread's continuation. - * There might not be an old thread, if we are - * the first thread to run on this processor. - */ - if (old_thread != THREAD_NULL) - thread_dispatch(old_thread); - - if (self->funnel_state & TH_FN_REFUNNEL) { - kern_return_t wait_result = self->wait_result; - - self->funnel_state = 0; - KERNEL_DEBUG(0x6032428 | DBG_FUNC_NONE, self->funnel_lock, 4, 0, 0, 0); - funnel_lock(self->funnel_lock); - KERNEL_DEBUG(0x6032430 | DBG_FUNC_NONE, self->funnel_lock, 4, 0, 0, 0); - self->funnel_state = TH_FN_OWNED; - self->wait_result = wait_result; - } - (void)spllo(); - assert(continuation); - call_continuation(continuation); - /*NOTREACHED*/ -} +#if 0 +#define IDLE_KERNEL_DEBUG_CONSTANT(...) KERNEL_DEBUG_CONSTANT(__VA_ARGS__) +#else +#define IDLE_KERNEL_DEBUG_CONSTANT(...) do { } while(0) +#endif + +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(); -#if MACH_LDEBUG || MACH_KDB + 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); -#define THREAD_LOG_SIZE 300 + SCHED_STATS_CPU_IDLE_START(processor); -struct t64 { - unsigned long h; - unsigned long l; -}; + uint64_t ctime = mach_absolute_time(); -struct { - struct t64 stamp; - thread_t thread; - long info1; - long info2; - long info3; - char * action; -} thread_log[THREAD_LOG_SIZE]; + timer_switch(&PROCESSOR_DATA(processor, system_state), ctime, &PROCESSOR_DATA(processor, idle_state)); + PROCESSOR_DATA(processor, current_state) = &PROCESSOR_DATA(processor, idle_state); -int thread_log_index; + cpu_quiescent_counter_leave(ctime); -void check_thread_time(long n); + while (1) { + /* + * Ensure that updates to my processor and pset state, + * made by the IPI source processor before sending the IPI, + * are visible on this processor now (even though we don't + * take the pset lock yet). + */ + atomic_thread_fence(memory_order_acquire); + + if (processor->state != PROCESSOR_IDLE) + break; + if (bit_test(pset->pending_AST_cpu_mask, processor->cpu_id)) + break; +#if defined(CONFIG_SCHED_DEFERRED_AST) + if (bit_test(pset->pending_deferred_AST_cpu_mask, processor->cpu_id)) + break; +#endif + if (processor->is_recommended && (processor->processor_primary == processor)) { + if (rt_runq_count(pset)) + 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 -int check_thread_time_crash; + IDLE_KERNEL_DEBUG_CONSTANT( + MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_NONE, (uintptr_t)thread_tid(thread), rt_runq_count(pset), SCHED(processor_runq_count)(processor), -1, 0); -#if 0 -void -check_thread_time(long us) -{ - struct t64 temp; + machine_track_platform_idle(TRUE); - if (!check_thread_time_crash) - return; + machine_idle(); - temp = thread_log[0].stamp; - cyctm05_diff (&thread_log[1].stamp, &thread_log[0].stamp, &temp); + machine_track_platform_idle(FALSE); - if (temp.l >= us && thread_log[1].info != 0x49) /* HACK!!! */ - panic ("check_thread_time"); -} -#endif + (void)splsched(); -void -log_thread_action(char * action, long info1, long info2, long info3) -{ - int i; - spl_t x; - static unsigned int tstamp; + /* + * Check if we should call sched_timeshare_consider_maintenance() here. + * The CPU was woken out of idle due to an interrupt and we should do the + * call only if the processor is still idle. If the processor is non-idle, + * the threads running on the processor would do the call as part of + * context swithing. + */ + if (processor->state == PROCESSOR_IDLE) { + sched_timeshare_consider_maintenance(mach_absolute_time()); + } - x = splhigh(); + IDLE_KERNEL_DEBUG_CONSTANT( + MACHDBG_CODE(DBG_MACH_SCHED,MACH_IDLE) | DBG_FUNC_NONE, (uintptr_t)thread_tid(thread), rt_runq_count(pset), SCHED(processor_runq_count)(processor), -2, 0); - for (i = THREAD_LOG_SIZE-1; i > 0; i--) { - thread_log[i] = thread_log[i-1]; + 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; + } } - thread_log[0].stamp.h = 0; - thread_log[0].stamp.l = tstamp++; - thread_log[0].thread = current_thread(); - thread_log[0].info1 = info1; - thread_log[0].info2 = info2; - thread_log[0].info3 = info3; - thread_log[0].action = action; -/* strcpy (&thread_log[0].action[0], action);*/ + ctime = mach_absolute_time(); - splx(x); -} -#endif /* MACH_LDEBUG || MACH_KDB */ + timer_switch(&PROCESSOR_DATA(processor, idle_state), ctime, &PROCESSOR_DATA(processor, system_state)); + PROCESSOR_DATA(processor, current_state) = &PROCESSOR_DATA(processor, system_state); -#if MACH_KDB -#include -void db_show_thread_log(void); + cpu_quiescent_counter_join(ctime); -void -db_show_thread_log(void) -{ - int i; + pset_lock(pset); + + /* If we were sent a remote AST and came out of idle, acknowledge it here with pset lock held */ + bit_clear(pset->pending_AST_cpu_mask, processor->cpu_id); +#if defined(CONFIG_SCHED_DEFERRED_AST) + bit_clear(pset->pending_deferred_AST_cpu_mask, processor->cpu_id); +#endif - db_printf ("%s %s %s %s %s %s\n", " Thread ", " Info1 ", " Info2 ", - " Info3 ", " Timestamp ", "Action"); + state = processor->state; + if (state == PROCESSOR_DISPATCHING) { + /* + * Commmon case -- cpu dispatched. + */ + new_thread = processor->next_thread; + processor->next_thread = THREAD_NULL; + pset_update_processor_state(pset, processor, PROCESSOR_RUNNING); - for (i = 0; i < THREAD_LOG_SIZE; i++) { - db_printf ("%08x %08x %08x %08x %08x/%08x %s\n", - thread_log[i].thread, - thread_log[i].info1, - thread_log[i].info2, - thread_log[i].info3, - thread_log[i].stamp.h, - thread_log[i].stamp.l, - thread_log[i].action); - } -} -#endif /* MACH_KDB */ + if ((new_thread != THREAD_NULL) && (SCHED(processor_queue_has_priority)(processor, new_thread->sched_pri, FALSE) || + (rt_runq_count(pset) > 0)) ) { + /* Something higher priority has popped up on the runqueue - redispatch this thread elsewhere */ + processor_state_update_idle(processor); + processor->deadline = UINT64_MAX; -/* - * thread_block_reason: - * - * Block the current thread if a wait has been asserted, - * otherwise unconditionally yield the remainder of the - * current quantum unless reason contains AST_BLOCK. - * - * If a continuation is specified, then thread_block 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;) - -int -thread_block_reason( - thread_continue_t continuation, - ast_t reason) -{ - register thread_t thread = current_thread(); - register processor_t myprocessor; - register thread_t new_thread; - spl_t s; + pset_unlock(pset); - counter(++c_thread_block_calls); + 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(pset), 0, 0); + thread_setrun(new_thread, SCHED_HEADQ); + thread_unlock(new_thread); - check_simple_locks(); + 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); - machine_clock_assist(); + return (THREAD_NULL); + } - s = splsched(); + sched_update_pset_load_average(pset); - if ((thread->funnel_state & TH_FN_OWNED) && !(reason & AST_PREEMPT)) { - thread->funnel_state = TH_FN_REFUNNEL; - KERNEL_DEBUG( - 0x603242c | DBG_FUNC_NONE, thread->funnel_lock, 2, 0, 0, 0); - funnel_unlock(thread->funnel_lock); - } + pset_unlock(pset); - myprocessor = current_processor(); + 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); - /* If we're explicitly yielding, force a subsequent quantum */ - if (reason & AST_YIELD) - myprocessor->slice_quanta = 0; + return (new_thread); - /* We're handling all scheduling AST's */ - ast_off(AST_SCHEDULING); + } else if (state == PROCESSOR_IDLE) { + pset_update_processor_state(pset, processor, PROCESSOR_RUNNING); + processor_state_update_idle(processor); + processor->deadline = UINT64_MAX; - thread_lock(thread); - new_thread = thread_select(myprocessor); - assert(new_thread && thread_runnable(new_thread)); - thread_unlock(thread); - while (!thread_invoke(thread, new_thread, reason, continuation)) { - thread_lock(thread); - new_thread = thread_select(myprocessor); - assert(new_thread && thread_runnable(new_thread)); - thread_unlock(thread); - } + } else if (state == PROCESSOR_SHUTDOWN) { + /* + * Going off-line. Force a + * reschedule. + */ + if ((new_thread = processor->next_thread) != THREAD_NULL) { + processor->next_thread = THREAD_NULL; + processor_state_update_idle(processor); + processor->deadline = UINT64_MAX; + + pset_unlock(pset); - if (thread->funnel_state & TH_FN_REFUNNEL) { - kern_return_t wait_result = thread->wait_result; + thread_lock(new_thread); + thread_setrun(new_thread, SCHED_HEADQ); + thread_unlock(new_thread); - thread->funnel_state = 0; - KERNEL_DEBUG( - 0x6032428 | DBG_FUNC_NONE, thread->funnel_lock, 5, 0, 0, 0); - funnel_lock(thread->funnel_lock); - KERNEL_DEBUG( - 0x6032430 | DBG_FUNC_NONE, thread->funnel_lock, 5, 0, 0, 0); - thread->funnel_state = TH_FN_OWNED; - thread->wait_result = wait_result; + 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); + } } - splx(s); + pset_unlock(pset); - return (thread->wait_result); + 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); } /* - * thread_block: - * - * Block the current thread if a wait has been asserted. + * Each processor has a dedicated thread which + * executes the idle loop when there is no suitable + * previous context. */ -int -thread_block( - thread_continue_t continuation) +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*/ + } + + thread_block((thread_continue_t)idle_thread); + /*NOTREACHED*/ +} + +kern_return_t +idle_thread_create( + processor_t processor) { - return thread_block_reason(continuation, AST_NONE); + kern_return_t result; + thread_t thread; + spl_t s; + char name[MAXTHREADNAMESIZE]; + + result = kernel_thread_create((thread_continue_t)idle_thread, NULL, MAXPRI_KERNEL, &thread); + if (result != KERN_SUCCESS) + return (result); + + snprintf(name, sizeof(name), "idle #%d", processor->cpu_id); + thread_set_thread_name(thread, name); + + s = splsched(); + thread_lock(thread); + thread->bound_processor = processor; + processor->idle_thread = thread; + thread->sched_pri = thread->base_pri = IDLEPRI; + thread->state = (TH_RUN | TH_IDLE); + thread->options |= TH_OPT_IDLE_THREAD; + thread_unlock(thread); + splx(s); + + thread_deallocate(thread); + + return (KERN_SUCCESS); } /* - * thread_run: + * sched_startup: * - * Switch directly from the current (old) thread to the - * specified thread, handing off our quantum if possible. + * Kicks off scheduler services. * - * New thread must be runnable, and not on a run queue. - * - * Assumption: - * at splsched. + * Called at splsched. */ -int -thread_run( - thread_t old_thread, - thread_continue_t continuation, - thread_t new_thread) +void +sched_startup(void) { - ast_t handoff = AST_HANDOFF; + kern_return_t result; + thread_t thread; - assert(old_thread == current_thread()); + simple_lock_init(&sched_vm_group_list_lock, 0); - machine_clock_assist(); +#if __arm__ || __arm64__ + simple_lock_init(&sched_recommended_cores_lock, 0); +#endif /* __arm__ || __arm64__ */ - if (old_thread->funnel_state & TH_FN_OWNED) { - old_thread->funnel_state = TH_FN_REFUNNEL; - KERNEL_DEBUG( - 0x603242c | DBG_FUNC_NONE, old_thread->funnel_lock, 3, 0, 0, 0); - funnel_unlock(old_thread->funnel_lock); - } + 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"); - while (!thread_invoke(old_thread, new_thread, handoff, continuation)) { - register processor_t myprocessor = current_processor(); + thread_deallocate(thread); - thread_lock(old_thread); - new_thread = thread_select(myprocessor); - thread_unlock(old_thread); - handoff = AST_NONE; - } + assert_thread_magic(thread); + + /* + * 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. + */ + thread_block(THREAD_CONTINUE_NULL); +} - /* if we fell thru */ - if (old_thread->funnel_state & TH_FN_REFUNNEL) { - kern_return_t wait_result = old_thread->wait_result; +#if __arm64__ +static _Atomic uint64_t sched_perfcontrol_callback_deadline; +#endif /* __arm64__ */ - old_thread->funnel_state = 0; - KERNEL_DEBUG( - 0x6032428 | DBG_FUNC_NONE, old_thread->funnel_lock, 6, 0, 0, 0); - funnel_lock(old_thread->funnel_lock); - KERNEL_DEBUG( - 0x6032430 | DBG_FUNC_NONE, old_thread->funnel_lock, 6, 0, 0, 0); - old_thread->funnel_state = TH_FN_OWNED; - old_thread->wait_result = wait_result; - } - return (old_thread->wait_result); -} +#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; + /* - * Dispatches a running thread that is not on a runq. - * Called at splsched. + * sched_init_thread: + * + * Perform periodic bookkeeping functions about ten + * times per second. */ void -thread_dispatch( - register thread_t thread) +sched_timeshare_maintenance_continue(void) { - wake_lock(thread); - thread_lock(thread); + 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); + + /* 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; + + update_vm_info(); /* - * If we are discarding the thread's stack, we must do it - * before the thread has a chance to run. + * Compute various averages. */ -#ifndef i386 - if (thread->continuation != NULL) { - assert((thread->state & TH_STACK_STATE) == 0); - thread->state |= TH_STACK_HANDOFF; - stack_free(thread); - } -#endif + compute_averages(sched_tick_delta); - switch (thread->state & (TH_RUN|TH_WAIT|TH_UNINT|TH_IDLE)) { + /* + * Scan the run queues for threads which + * may need to be updated, and find the earliest runnable thread on the runqueue + * to report its latency. + */ + SCHED(thread_update_scan)(&scan_context); - case TH_RUN | TH_UNINT: - case TH_RUN: - /* - * No reason to stop. Put back on a run queue. - */ - _mk_sp_thread_dispatch(thread); - break; + SCHED(rt_runq_scan)(&scan_context); - case TH_RUN | TH_WAIT | TH_UNINT: - case TH_RUN | TH_WAIT: - { - boolean_t reap, wake, callblock; - - /* - * Waiting - */ - thread->sleep_stamp = sched_tick; - thread->state &= ~TH_RUN; - hw_atomic_sub(&thread->processor_set->run_count, 1); - callblock = thread->active_callout; - wake = thread->wake_active; - thread->wake_active = FALSE; - reap = (thread->state & TH_TERMINATE)? TRUE: FALSE; + uint64_t ctime = mach_absolute_time(); - thread_unlock(thread); - wake_unlock(thread); + uint64_t bg_max_latency = (ctime > scan_context.earliest_bg_make_runnable_time) ? + ctime - scan_context.earliest_bg_make_runnable_time : 0; - if (callblock) - call_thread_block(); + uint64_t default_max_latency = (ctime > scan_context.earliest_normal_make_runnable_time) ? + ctime - scan_context.earliest_normal_make_runnable_time : 0; - if (wake) - thread_wakeup((event_t)&thread->wake_active); + uint64_t realtime_max_latency = (ctime > scan_context.earliest_rt_make_runnable_time) ? + ctime - scan_context.earliest_rt_make_runnable_time : 0; - if (reap) - thread_reaper_enqueue(thread); + machine_max_runnable_latency(bg_max_latency, default_max_latency, realtime_max_latency); - return; + /* + * Check to see if the special sched VM group needs attention. + */ + sched_vm_group_maintenance(); + +#if __arm__ || __arm64__ + /* Check to see if the recommended cores failsafe is active */ + sched_recommended_cores_maintenance(); +#endif /* __arm__ || __arm64__ */ + + +#if DEBUG || DEVELOPMENT +#if __x86_64__ +#include + /* Check for long-duration interrupts */ + mp_interrupt_watchdog(); +#endif /* __x86_64__ */ +#endif /* DEBUG || DEVELOPMENT */ + + 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], sched_pri_shifts[TH_BUCKET_SHARE_DF], 0); + + 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; + +/* + * 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. + */ +void +sched_timeshare_consider_maintenance(uint64_t ctime) { + + cpu_quiescent_counter_checkin(ctime); + + uint64_t deadline = sched_maintenance_deadline; + + if (__improbable(ctime >= deadline)) { + if (__improbable(current_thread() == sched_maintenance_thread)) + return; + OSMemoryBarrier(); + + uint64_t ndeadline = ctime + sched_tick_interval; + + if (__probable(__sync_bool_compare_and_swap(&sched_maintenance_deadline, deadline, ndeadline))) { + thread_wakeup((event_t)sched_timeshare_maintenance_continue); + sched_maintenance_wakeups++; + } } - case TH_RUN | TH_IDLE: - /* - * The idle threads don't go - * onto a run queue. - */ - break; + uint64_t load_compute_deadline = __c11_atomic_load(&sched_load_compute_deadline, memory_order_relaxed); - default: - panic("thread_dispatch: bad thread state 0x%x\n", thread->state); + if (__improbable(load_compute_deadline && ctime >= load_compute_deadline)) { + uint64_t new_deadline = 0; + if (__c11_atomic_compare_exchange_strong(&sched_load_compute_deadline, &load_compute_deadline, new_deadline, + memory_order_relaxed, memory_order_relaxed)) { + compute_sched_load(); + new_deadline = ctime + sched_load_compute_interval_abs; + __c11_atomic_store(&sched_load_compute_deadline, new_deadline, memory_order_relaxed); + } } - thread_unlock(thread); - wake_unlock(thread); +#if __arm64__ + uint64_t perf_deadline = __c11_atomic_load(&sched_perfcontrol_callback_deadline, memory_order_relaxed); + + if (__improbable(perf_deadline && ctime >= perf_deadline)) { + /* CAS in 0, if success, make callback. Otherwise let the next context switch check again. */ + if (__c11_atomic_compare_exchange_strong(&sched_perfcontrol_callback_deadline, &perf_deadline, 0, + memory_order_relaxed, memory_order_relaxed)) { + machine_perfcontrol_deadline_passed(perf_deadline); + } + } +#endif /* __arm64__ */ + } -/* - * Enqueue thread on run queue. Thread must be locked, - * and not already be on a run queue. Returns TRUE iff - * the particular queue level was empty beforehand. - */ -boolean_t -run_queue_enqueue( - register run_queue_t rq, - register thread_t thread, - boolean_t tail) +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + +void +sched_init_thread(void (*continuation)(void)) { - register int whichq = thread->sched_pri; - register queue_t queue = &rq->queues[whichq]; - boolean_t result = FALSE; - - assert(whichq >= MINPRI && whichq <= MAXPRI); + thread_block(THREAD_CONTINUE_NULL); - simple_lock(&rq->lock); - assert(thread->runq == RUN_QUEUE_NULL); - if (queue_empty(queue)) { - enqueue_tail(queue, (queue_entry_t)thread); + thread_t thread = current_thread(); - setbit(MAXPRI - whichq, rq->bitmap); - if (whichq > rq->highq) - rq->highq = whichq; - result = TRUE; - } - else - if (tail) - enqueue_tail(queue, (queue_entry_t)thread); - else - enqueue_head(queue, (queue_entry_t)thread); + thread_set_thread_name(thread, "sched_maintenance_thread"); - thread->runq = rq; - if (thread->sched_mode & TH_MODE_PREEMPT) - rq->urgency++; - rq->count++; -#if DEBUG - thread_check(thread, rq); -#endif /* DEBUG */ - simple_unlock(&rq->lock); + sched_maintenance_thread = thread; - return (result); + continuation(); + + /*NOTREACHED*/ } -struct { - uint32_t pset_idle_last, - pset_idle_any, - pset_self, - pset_last, - pset_other, - bound_idle, - bound_self, - bound_other; -} dispatch_counts; +#if defined(CONFIG_SCHED_TIMESHARE_CORE) /* - * thread_setrun: + * thread_update_scan / runq_scan: * - * Dispatch thread for execution, directly onto an idle - * processor if possible. Else put on appropriate run - * queue. (local if bound, else processor set) + * Scan the run queues to account for timesharing threads + * which need to be updated. * - * Thread must be locked. + * Scanner runs in two passes. Pass one squirrels likely + * threads away in an array, pass two does the update. + * + * This is necessary because the run queue is locked for + * the candidate scan, but the thread is locked for the update. * - * The tail parameter indicates the proper placement of - * the thread on a run queue. + * Array should be sized to make forward progress, without + * disabling preemption for long periods. */ -void -thread_setrun( - register thread_t new_thread, - boolean_t tail) + +#define THREAD_UPDATE_SIZE 128 + +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) { - register processor_t processor; - register processor_set_t pset; - register thread_t thread; - boolean_t try_preempt = FALSE; - ast_t preempt = AST_BLOCK; + if (thread_update_count == THREAD_UPDATE_SIZE) + return (FALSE); - assert(thread_runnable(new_thread)); - - /* - * Update priority if needed. - */ - if (new_thread->sched_stamp != sched_tick) - update_priority(new_thread); + thread_update_array[thread_update_count++] = thread; + thread_reference_internal(thread); + return (TRUE); +} - /* - * Check for urgent preemption. - */ - if (new_thread->sched_mode & TH_MODE_PREEMPT) - preempt |= AST_URGENT; +void +thread_update_process_threads(void) +{ + assert(thread_update_count <= THREAD_UPDATE_SIZE); - assert(new_thread->runq == RUN_QUEUE_NULL); + 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; - 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 ) { - simple_lock(&processor->lock); - 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; - processor->state = PROCESSOR_DISPATCHING; - simple_unlock(&pset->sched_lock); - simple_unlock(&processor->lock); - if (processor != current_processor()) - machine_signal_idle(processor); - dispatch_counts.pset_idle_last++; - return; - } - simple_unlock(&processor->lock); + spl_t s = splsched(); + thread_lock(thread); + if (!(thread->state & (TH_WAIT)) && thread->sched_stamp != sched_tick) { + SCHED(update_priority)(thread); } - else - simple_lock(&pset->sched_lock); + thread_unlock(thread); + splx(s); - /* - * Next pick any idle processor - * in the processor set. - */ - if (pset->idle_count > 0) { - processor = (processor_t)dequeue_head(&pset->idle_queue); - pset->idle_count--; - processor->next_thread = new_thread; - processor->state = PROCESSOR_DISPATCHING; - simple_unlock(&pset->sched_lock); - if (processor != current_processor()) - machine_signal_idle(processor); - dispatch_counts.pset_idle_any++; - return; - } + thread_deallocate(thread); + } - /* - * Place thread on run queue. - */ - if (run_queue_enqueue(&pset->runq, new_thread, tail)) - try_preempt = TRUE; + thread_update_count = 0; +} - /* - * Update the timesharing quanta. - */ - pset_quanta_update(pset); - - /* - * Preempt check. - */ - processor = current_processor(); - thread = processor->cpu_data->active_thread; - if (try_preempt) { - /* - * First try the current processor - * if it is a member of the correct - * processor set. - */ - if ( pset == processor->processor_set && - csw_needed(thread, processor) ) { - simple_unlock(&pset->sched_lock); +/* + * Scan a runq for candidate threads. + * + * Returns TRUE if retry is needed. + */ +boolean_t +runq_scan( + run_queue_t runq, + sched_update_scan_context_t scan_context) +{ + int count = runq->count; + int queue_index; - ast_on(preempt); - dispatch_counts.pset_self++; - return; - } + assert(count >= 0); - /* - * If that failed and we have other - * processors available keep trying. - */ - if ( pset->processor_count > 1 || - pset != processor->processor_set ) { - queue_t active = &pset->active_queue; - processor_t myprocessor, lastprocessor; - queue_entry_t next; + if (count == 0) + return FALSE; - /* - * 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 ) { - cause_ast_check(processor); - simple_unlock(&pset->sched_lock); - dispatch_counts.pset_last++; - return; - } + for (queue_index = bitmap_first(runq->bitmap, NRQS); + queue_index >= 0; + queue_index = bitmap_next(runq->bitmap, queue_index)) { - /* - * Lastly, pick any other - * available processor. - */ - lastprocessor = processor; - processor = (processor_t)queue_first(active); - while (!queue_end(active, (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(active, next)) { - remqueue(active, (queue_entry_t)processor); - enqueue_tail(active, (queue_entry_t)processor); - } - cause_ast_check(processor); - simple_unlock(&pset->sched_lock); - dispatch_counts.pset_other++; - return; - } + thread_t thread; + queue_t queue = &runq->queues[queue_index]; - processor = (processor_t)next; - } - } - } + qe_foreach_element(thread, queue, runq_links) { + assert(count > 0); + assert_thread_magic(thread); - simple_unlock(&pset->sched_lock); - } - else { - /* - * Bound, can only run on bound processor. Have to lock - * processor here because it may not be the current one. - */ - if (processor->state == PROCESSOR_IDLE) { - simple_lock(&processor->lock); - pset = processor->processor_set; - 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->state = PROCESSOR_DISPATCHING; - simple_unlock(&pset->sched_lock); - simple_unlock(&processor->lock); - if (processor != current_processor()) - machine_signal_idle(processor); - dispatch_counts.bound_idle++; - return; + if (thread->sched_stamp != sched_tick && + thread->sched_mode == TH_MODE_TIMESHARE) { + if (thread_update_add_thread(thread) == FALSE) + return TRUE; } - simple_unlock(&pset->sched_lock); - simple_unlock(&processor->lock); - } - - if (run_queue_enqueue(&processor->runq, new_thread, tail)) - try_preempt = TRUE; - if (processor == current_processor()) { - if (try_preempt) { - thread = processor->cpu_data->active_thread; - if (csw_needed(thread, processor)) { - ast_on(preempt); - dispatch_counts.bound_self++; + 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 (try_preempt) { - if ( processor->state == PROCESSOR_RUNNING && - new_thread->sched_pri > processor->current_pri ) { - cause_ast_check(processor); - dispatch_counts.bound_other++; - return; + } 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; } } - - if (processor->state == PROCESSOR_IDLE) { - machine_signal_idle(processor); - dispatch_counts.bound_idle++; - } + count--; } } + + return FALSE; } -/* - * Called at splsched by a thread on itself. - */ -ast_t -csw_check( - thread_t thread, - processor_t processor) +#endif /* CONFIG_SCHED_TIMESHARE_CORE */ + +boolean_t +thread_eager_preemption(thread_t thread) { - int current_pri = thread->sched_pri; - ast_t result = AST_NONE; - run_queue_t runq; + return ((thread->sched_flags & TH_SFLAG_EAGERPREEMPT) != 0); +} - if (first_quantum(processor)) { - runq = &processor->processor_set->runq; - if (runq->highq > current_pri) { - if (runq->urgency > 0) - return (AST_BLOCK | AST_URGENT); +void +thread_set_eager_preempt(thread_t thread) +{ + spl_t x; + processor_t p; + ast_t ast = AST_NONE; - result |= AST_BLOCK; - } + x = splsched(); + p = current_processor(); - runq = &processor->runq; - if (runq->highq > current_pri) { - if (runq->urgency > 0) - return (AST_BLOCK | AST_URGENT); + thread_lock(thread); + thread->sched_flags |= TH_SFLAG_EAGERPREEMPT; - result |= AST_BLOCK; - } - } - else { - runq = &processor->processor_set->runq; - if (runq->highq >= current_pri) { - if (runq->urgency > 0) - return (AST_BLOCK | AST_URGENT); + if (thread == current_thread()) { - result |= AST_BLOCK; + ast = csw_check(p, AST_NONE); + thread_unlock(thread); + if (ast != AST_NONE) { + (void) thread_block_reason(THREAD_CONTINUE_NULL, NULL, ast); } + } else { + p = thread->last_processor; - runq = &processor->runq; - if (runq->highq >= current_pri) { - if (runq->urgency > 0) - return (AST_BLOCK | AST_URGENT); - - result |= AST_BLOCK; + if (p != PROCESSOR_NULL && p->state == PROCESSOR_RUNNING && + p->active_thread == thread) { + cause_ast_check(p); } + + thread_unlock(thread); } - if (result != AST_NONE) - return (result); + splx(x); +} - if (thread->state & TH_SUSP) - result |= AST_BLOCK; +void +thread_clear_eager_preempt(thread_t thread) +{ + spl_t x; - return (result); + x = splsched(); + thread_lock(thread); + + thread->sched_flags &= ~TH_SFLAG_EAGERPREEMPT; + + thread_unlock(thread); + splx(x); } /* - * set_sched_pri: - * - * Set the current scheduled priority of the specified thread. - * This may cause the thread to change queues. - * - * The thread *must* be locked by the caller. + * Scheduling statistics */ void -set_sched_pri( - thread_t thread, - int priority) +sched_stats_handle_csw(processor_t processor, int reasons, int selfpri, int otherpri) { - register struct run_queue *rq = rem_runq(thread); + struct processor_sched_statistics *stats; + boolean_t to_realtime = FALSE; + + stats = &processor->processor_data.sched_stats; + stats->csw_count++; - 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_FORCEDPREEMPT) ) ) - thread->sched_mode |= TH_MODE_PREEMPT; - else - thread->sched_mode &= ~TH_MODE_PREEMPT; + if (otherpri >= BASEPRI_REALTIME) { + stats->rt_sched_count++; + to_realtime = TRUE; + } - thread->sched_pri = priority; - if (rq != RUN_QUEUE_NULL) - thread_setrun(thread, TAIL_Q); - else - if ((thread->state & (TH_RUN|TH_WAIT)) == TH_RUN) { - processor_t processor = thread->last_processor; + if ((reasons & AST_PREEMPT) != 0) { + stats->preempt_count++; - if (thread == current_thread()) { - ast_t preempt = csw_check(thread, processor); + if (selfpri >= BASEPRI_REALTIME) { + stats->preempted_rt_count++; + } - if (preempt != AST_NONE) - ast_on(preempt); - processor->current_pri = priority; + if (to_realtime) { + stats->preempted_by_rt_count++; } - else - if ( processor != PROCESSOR_NULL && - processor->cpu_data->active_thread == thread ) - cause_ast_check(processor); + } } +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; +} + /* - * rem_runq: - * - * Remove a thread from its run queue. - * The run queue that the process was on is returned - * (or RUN_QUEUE_NULL if not on a run queue). Thread *must* be locked - * before calling this routine. Unusual locking protocol on runq - * field in thread structure makes this code interesting; see thread.h. + * For calls from assembly code */ -run_queue_t -rem_runq( - thread_t thread) +#undef thread_wakeup +void +thread_wakeup( + event_t x); + +void +thread_wakeup( + event_t x) { - register struct run_queue *rq; + thread_wakeup_with_result(x, THREAD_AWAKENED); +} - 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 runq, but could leave. - */ - if (rq != RUN_QUEUE_NULL) { - simple_lock(&rq->lock); - if (rq == thread->runq) { - /* - * Thread is in a runq and we have a lock on - * that runq. - */ -#if DEBUG - thread_check(thread, rq); -#endif /* DEBUG */ - 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->runq = RUN_QUEUE_NULL; - simple_unlock(&rq->lock); - } - else { - /* - * The thread left the runq before we could - * lock the runq. It is not on a runq now, and - * can't move again because this routine's - * caller locked the thread. - */ - assert(thread->runq == RUN_QUEUE_NULL); - simple_unlock(&rq->lock); - rq = RUN_QUEUE_NULL; - } - } +boolean_t +preemption_enabled(void) +{ + return (get_preemption_level() == 0 && ml_get_interrupts_enabled()); +} - return (rq); +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); } +#if __arm__ || __arm64__ + +uint32_t perfcontrol_requested_recommended_cores = ALL_CORES_RECOMMENDED; +uint32_t perfcontrol_requested_recommended_core_count = MAX_CPUS; +bool perfcontrol_failsafe_active = false; +bool perfcontrol_sleep_override = false; + +uint64_t perfcontrol_failsafe_maintenance_runnable_time; +uint64_t perfcontrol_failsafe_activation_time; +uint64_t perfcontrol_failsafe_deactivation_time; + +/* data covering who likely caused it and how long they ran */ +#define FAILSAFE_NAME_LEN 33 /* (2*MAXCOMLEN)+1 from size of p_name */ +char perfcontrol_failsafe_name[FAILSAFE_NAME_LEN]; +int perfcontrol_failsafe_pid; +uint64_t perfcontrol_failsafe_tid; +uint64_t perfcontrol_failsafe_thread_timer_at_start; +uint64_t perfcontrol_failsafe_thread_timer_last_seen; +uint32_t perfcontrol_failsafe_recommended_at_trigger; + /* - * choose_thread: + * Perf controller calls here to update the recommended core bitmask. + * If the failsafe is active, we don't immediately apply the new value. + * Instead, we store the new request and use it after the failsafe deactivates. * - * Choose a thread to execute. The thread chosen is removed - * from its run queue. Note that this requires only that the runq - * lock be held. + * If the failsafe is not active, immediately apply the update. * - * Strategy: - * Check processor runq first; if anything found, run it. - * Else check pset runq; if nothing found, return idle thread. + * No scheduler locks are held, no other locks are held that scheduler might depend on, + * interrupts are enabled * - * Second line of strategy is implemented by choose_pset_thread. - * - * Called with both the local & pset run queues locked, returned - * unlocked. + * currently prototype is in osfmk/arm/machine_routines.h */ -thread_t -choose_thread( - processor_t myprocessor) -{ - thread_t thread; - register queue_t q; - register run_queue_t runq; - processor_set_t pset; - - runq = &myprocessor->runq; - pset = myprocessor->processor_set; - - if (runq->count > 0 && runq->highq >= pset->runq.highq) { - simple_unlock(&pset->runq.lock); - q = runq->queues + runq->highq; -#if MACH_ASSERT - if (!queue_empty(q)) { -#endif /*MACH_ASSERT*/ - 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); - } - simple_unlock(&runq->lock); - return (thread); -#if MACH_ASSERT - } - panic("choose_thread"); -#endif /*MACH_ASSERT*/ - /*NOTREACHED*/ - } - simple_unlock(&myprocessor->runq.lock); +void +sched_perfcontrol_update_recommended_cores(uint32_t recommended_cores) +{ + assert(preemption_enabled()); - return (choose_pset_thread(myprocessor, pset)); + spl_t s = splsched(); + simple_lock(&sched_recommended_cores_lock); + + perfcontrol_requested_recommended_cores = recommended_cores; + perfcontrol_requested_recommended_core_count = __builtin_popcountll(recommended_cores); + + if ((perfcontrol_failsafe_active == false) && (perfcontrol_sleep_override == false)) + sched_update_recommended_cores(perfcontrol_requested_recommended_cores); + else + KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE, + MACHDBG_CODE(DBG_MACH_SCHED,MACH_REC_CORES_FAILSAFE) | DBG_FUNC_NONE, + perfcontrol_requested_recommended_cores, + sched_maintenance_thread->last_made_runnable_time, 0, 0, 0); + + simple_unlock(&sched_recommended_cores_lock); + splx(s); } -/* - * choose_pset_thread: choose a thread from processor_set runq or - * set processor idle and choose its idle thread. - * - * This routine chooses and removes a thread from the runq if there - * is one (and returns it), else it sets the processor idle and - * returns its idle thread. - * - * Called with both local & pset run queues locked, returned - * unlocked. - */ -thread_t -choose_pset_thread( - register processor_t myprocessor, - processor_set_t pset) -{ - register run_queue_t runq; - register thread_t thread; - register queue_t q; - - runq = &pset->runq; - if (runq->count > 0) { - q = runq->queues + runq->highq; -#if MACH_ASSERT - if (!queue_empty(q)) { -#endif /*MACH_ASSERT*/ - 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); - } - pset_quanta_update(pset); - simple_unlock(&runq->lock); - return (thread); -#if MACH_ASSERT - } - panic("choose_pset_thread"); -#endif /*MACH_ASSERT*/ - /*NOTREACHED*/ +void +sched_override_recommended_cores_for_sleep(void) +{ + spl_t s = splsched(); + simple_lock(&sched_recommended_cores_lock); + + if (perfcontrol_sleep_override == false) { + perfcontrol_sleep_override = true; + sched_update_recommended_cores(ALL_CORES_RECOMMENDED); } - simple_unlock(&runq->lock); - /* - * Nothing is runnable, so set this processor idle if it - * was running. If it was in an assignment or shutdown, - * leave it alone. Return its idle thread. - */ - simple_lock(&pset->sched_lock); - if (myprocessor->state == PROCESSOR_RUNNING) { - remqueue(&pset->active_queue, (queue_entry_t)myprocessor); - myprocessor->state = PROCESSOR_IDLE; + simple_unlock(&sched_recommended_cores_lock); + splx(s); +} - if (myprocessor == master_processor) - enqueue_tail(&pset->idle_queue, (queue_entry_t)myprocessor); - else - enqueue_head(&pset->idle_queue, (queue_entry_t)myprocessor); +void +sched_restore_recommended_cores_after_sleep(void) +{ + spl_t s = splsched(); + simple_lock(&sched_recommended_cores_lock); - pset->idle_count++; + if (perfcontrol_sleep_override == true) { + perfcontrol_sleep_override = false; + sched_update_recommended_cores(perfcontrol_requested_recommended_cores); } - simple_unlock(&pset->sched_lock); - return (myprocessor->idle_thread); + simple_unlock(&sched_recommended_cores_lock); + splx(s); } /* - * 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 thread, which just looks for other threads - * to execute. + * Consider whether we need to activate the recommended cores failsafe + * + * Called from quantum timer interrupt context of a realtime thread + * No scheduler locks are held, interrupts are disabled */ void -idle_thread_continue(void) +sched_consider_recommended_cores(uint64_t ctime, thread_t cur_thread) { - register processor_t myprocessor; - register volatile thread_t *threadp; - register volatile int *gcount; - register volatile int *lcount; - register thread_t new_thread; - register int state; - register processor_set_t pset; - int mycpu; - - mycpu = cpu_number(); - myprocessor = cpu_to_processor(mycpu); - threadp = (volatile thread_t *) &myprocessor->next_thread; - lcount = (volatile int *) &myprocessor->runq.count; + /* + * Check if a realtime thread is starving the system + * and bringing up non-recommended cores would help + * + * TODO: Is this the correct check for recommended == possible cores? + * TODO: Validate the checks without the relevant lock are OK. + */ - for (;;) { - gcount = (volatile int *)&myprocessor->processor_set->runq.count; + if (__improbable(perfcontrol_failsafe_active == TRUE)) { + /* keep track of how long the responsible thread runs */ - (void)splsched(); - while ( (*threadp == (volatile thread_t)THREAD_NULL) && - (*gcount == 0) && (*lcount == 0) ) { - - /* check for ASTs while we wait */ - if (need_ast[mycpu] &~ ( AST_SCHEDULING | AST_BSD )) { - /* don't allow scheduling ASTs */ - need_ast[mycpu] &= ~( AST_SCHEDULING | AST_BSD ); - ast_taken(AST_ALL, TRUE); /* back at spllo */ - } - else -#ifdef __ppc__ - machine_idle(); -#else - (void)spllo(); -#endif - machine_clock_assist(); + simple_lock(&sched_recommended_cores_lock); - (void)splsched(); + if (perfcontrol_failsafe_active == TRUE && + cur_thread->thread_id == perfcontrol_failsafe_tid) { + perfcontrol_failsafe_thread_timer_last_seen = timer_grab(&cur_thread->user_timer) + + timer_grab(&cur_thread->system_timer); } + simple_unlock(&sched_recommended_cores_lock); + + /* we're already trying to solve the problem, so bail */ + return; + } + + /* The failsafe won't help if there are no more processors to enable */ + if (__probable(perfcontrol_requested_recommended_core_count >= processor_count)) + return; + + uint64_t too_long_ago = ctime - perfcontrol_failsafe_starvation_threshold; + + /* Use the maintenance thread as our canary in the coal mine */ + thread_t m_thread = sched_maintenance_thread; + + /* If it doesn't look bad, nothing to see here */ + if (__probable(m_thread->last_made_runnable_time >= too_long_ago)) + return; + + /* It looks bad, take the lock to be sure */ + thread_lock(m_thread); + + if (m_thread->runq == PROCESSOR_NULL || + (m_thread->state & (TH_RUN|TH_WAIT)) != TH_RUN || + m_thread->last_made_runnable_time >= too_long_ago) { /* - * This is not a switch statement to avoid the - * bounds checking code in the common case. + * Maintenance thread is either on cpu or blocked, and + * therefore wouldn't benefit from more cores */ - pset = myprocessor->processor_set; - simple_lock(&pset->sched_lock); -retry: - state = myprocessor->state; - if (state == PROCESSOR_DISPATCHING) { - /* - * Commmon case -- cpu dispatched. - */ - new_thread = *threadp; - *threadp = (volatile thread_t) THREAD_NULL; - myprocessor->state = PROCESSOR_RUNNING; - enqueue_tail(&pset->active_queue, (queue_entry_t)myprocessor); - simple_unlock(&pset->sched_lock); - - if ( myprocessor->runq.highq > new_thread->sched_pri || - pset->runq.highq > new_thread->sched_pri ) { - thread_lock(new_thread); - thread_setrun(new_thread, HEAD_Q); - thread_unlock(new_thread); - - counter(c_idle_thread_block++); - thread_block(idle_thread_continue); - /* NOTREACHED */ - } - else { - counter(c_idle_thread_handoff++); - thread_run(myprocessor->idle_thread, - idle_thread_continue, new_thread); - /* NOTREACHED */ - } - } - else - if (state == PROCESSOR_IDLE) { - if (myprocessor->state != PROCESSOR_IDLE) { - /* - * Something happened, try again. - */ - goto retry; - } - /* - * Processor was not dispatched (Rare). - * Set it running again. - */ - no_dispatch_count++; - pset->idle_count--; - remqueue(&pset->idle_queue, (queue_entry_t)myprocessor); - myprocessor->state = PROCESSOR_RUNNING; - enqueue_tail(&pset->active_queue, (queue_entry_t)myprocessor); - simple_unlock(&pset->sched_lock); + thread_unlock(m_thread); + return; + } - counter(c_idle_thread_block++); - thread_block(idle_thread_continue); - /* NOTREACHED */ - } - else - if ( state == PROCESSOR_ASSIGN || - state == PROCESSOR_SHUTDOWN ) { - /* - * Changing processor sets, or going off-line. - * Release next_thread if there is one. Actual - * thread to run is on a runq. - */ - if ((new_thread = (thread_t)*threadp) != THREAD_NULL) { - *threadp = (volatile thread_t) THREAD_NULL; - simple_unlock(&pset->sched_lock); + uint64_t maintenance_runnable_time = m_thread->last_made_runnable_time; - thread_lock(new_thread); - thread_setrun(new_thread, TAIL_Q); - thread_unlock(new_thread); - } - else - simple_unlock(&pset->sched_lock); + thread_unlock(m_thread); - counter(c_idle_thread_block++); - thread_block(idle_thread_continue); - /* NOTREACHED */ - } - else { - simple_unlock(&pset->sched_lock); + /* + * There are cores disabled at perfcontrol's recommendation, but the + * system is so overloaded that the maintenance thread can't run. + * That likely means that perfcontrol can't run either, so it can't fix + * the recommendation. We have to kick in a failsafe to keep from starving. + * + * When the maintenance thread has been starved for too long, + * ignore the recommendation from perfcontrol and light up all the cores. + * + * TODO: Consider weird states like boot, sleep, or debugger + */ - panic("idle_thread: bad processor state %d\n", cpu_state(mycpu)); - } + simple_lock(&sched_recommended_cores_lock); - (void)spllo(); + if (perfcontrol_failsafe_active == TRUE) { + simple_unlock(&sched_recommended_cores_lock); + return; } -} -void -idle_thread(void) -{ - thread_t self = current_thread(); - spl_t s; + KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE, + MACHDBG_CODE(DBG_MACH_SCHED,MACH_REC_CORES_FAILSAFE) | DBG_FUNC_START, + perfcontrol_requested_recommended_cores, maintenance_runnable_time, 0, 0, 0); - stack_privilege(self); + perfcontrol_failsafe_active = TRUE; + perfcontrol_failsafe_activation_time = mach_absolute_time(); + perfcontrol_failsafe_maintenance_runnable_time = maintenance_runnable_time; + perfcontrol_failsafe_recommended_at_trigger = perfcontrol_requested_recommended_cores; - s = splsched(); - thread_lock(self); - self->priority = IDLEPRI; - set_sched_pri(self, self->priority); - thread_unlock(self); - splx(s); + /* Capture some data about who screwed up (assuming that the thread on core is at fault) */ + task_t task = cur_thread->task; + perfcontrol_failsafe_pid = task_pid(task); + strlcpy(perfcontrol_failsafe_name, proc_name_address(task->bsd_info), sizeof(perfcontrol_failsafe_name)); - counter(c_idle_thread_block++); - thread_block(idle_thread_continue); - /*NOTREACHED*/ -} + perfcontrol_failsafe_tid = cur_thread->thread_id; -static uint64_t sched_tick_interval, sched_tick_deadline; + /* Blame the thread for time it has run recently */ + uint64_t recent_computation = (ctime - cur_thread->computation_epoch) + cur_thread->computation_metered; -void sched_tick_thread(void); + uint64_t last_seen = timer_grab(&cur_thread->user_timer) + timer_grab(&cur_thread->system_timer); -void -sched_tick_init(void) -{ - kernel_thread_with_priority( - kernel_task, MAXPRI_STANDARD, - sched_tick_thread, TRUE, TRUE); + /* Compute the start time of the bad behavior in terms of the thread's on core time */ + perfcontrol_failsafe_thread_timer_at_start = last_seen - recent_computation; + perfcontrol_failsafe_thread_timer_last_seen = last_seen; + + /* Ignore the previously recommended core configuration */ + sched_update_recommended_cores(ALL_CORES_RECOMMENDED); + + simple_unlock(&sched_recommended_cores_lock); } /* - * sched_tick_thread + * Now that our bacon has been saved by the failsafe, consider whether to turn it off * - * Update the priorities of all threads periodically. + * Runs in the context of the maintenance thread, no locks held */ -void -sched_tick_thread_continue(void) +static void +sched_recommended_cores_maintenance(void) { - uint64_t abstime; -#if SIMPLE_CLOCK - int new_usec; -#endif /* SIMPLE_CLOCK */ + /* Common case - no failsafe, nothing to be done here */ + if (__probable(perfcontrol_failsafe_active == FALSE)) + return; - clock_get_uptime(&abstime); + uint64_t ctime = mach_absolute_time(); - sched_tick++; /* age usage one more time */ -#if SIMPLE_CLOCK - /* - * Compensate for clock drift. sched_usec is an - * exponential average of the number of microseconds in - * a second. It decays in the same fashion as cpu_usage. - */ - new_usec = sched_usec_elapsed(); - sched_usec = (5*sched_usec + 3*new_usec)/8; -#endif /* SIMPLE_CLOCK */ + boolean_t print_diagnostic = FALSE; + char p_name[FAILSAFE_NAME_LEN] = ""; - /* - * Compute the scheduler load factors. - */ - compute_mach_factor(); + spl_t s = splsched(); + simple_lock(&sched_recommended_cores_lock); + + /* Check again, under the lock, to avoid races */ + if (perfcontrol_failsafe_active == FALSE) + goto out; /* - * Scan the run queues for runnable threads that need to - * have their priorities recalculated. + * Ensure that the other cores get another few ticks to run some threads + * If we don't have this hysteresis, the maintenance thread is the first + * to run, and then it immediately kills the other cores */ - do_thread_scan(); + if ((ctime - perfcontrol_failsafe_activation_time) < perfcontrol_failsafe_starvation_threshold) + goto out; - clock_deadline_for_periodic_event(sched_tick_interval, abstime, - &sched_tick_deadline); + /* Capture some diagnostic state under the lock so we can print it out later */ - assert_wait((event_t)sched_tick_thread_continue, THREAD_INTERRUPTIBLE); - thread_set_timer_deadline(sched_tick_deadline); - thread_block(sched_tick_thread_continue); - /*NOTREACHED*/ -} + int pid = perfcontrol_failsafe_pid; + uint64_t tid = perfcontrol_failsafe_tid; -void -sched_tick_thread(void) -{ - thread_t self = current_thread(); - natural_t rate; - spl_t s; + uint64_t thread_usage = perfcontrol_failsafe_thread_timer_last_seen - + perfcontrol_failsafe_thread_timer_at_start; + uint32_t rec_cores_before = perfcontrol_failsafe_recommended_at_trigger; + uint32_t rec_cores_after = perfcontrol_requested_recommended_cores; + uint64_t failsafe_duration = ctime - perfcontrol_failsafe_activation_time; + strlcpy(p_name, perfcontrol_failsafe_name, sizeof(p_name)); - stack_privilege(self); + print_diagnostic = TRUE; - rate = (1000 >> SCHED_TICK_SHIFT); - clock_interval_to_absolutetime_interval(rate, USEC_PER_SEC, - &sched_tick_interval); - clock_get_uptime(&sched_tick_deadline); + /* Deactivate the failsafe and reinstate the requested recommendation settings */ - thread_block(sched_tick_thread_continue); - /*NOTREACHED*/ -} + perfcontrol_failsafe_deactivation_time = ctime; + perfcontrol_failsafe_active = FALSE; + + KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE, + MACHDBG_CODE(DBG_MACH_SCHED,MACH_REC_CORES_FAILSAFE) | DBG_FUNC_END, + perfcontrol_requested_recommended_cores, failsafe_duration, 0, 0, 0); -#define MAX_STUCK_THREADS 128 + sched_update_recommended_cores(perfcontrol_requested_recommended_cores); + +out: + simple_unlock(&sched_recommended_cores_lock); + splx(s); + + if (print_diagnostic) { + uint64_t failsafe_duration_ms = 0, thread_usage_ms = 0; + + absolutetime_to_nanoseconds(failsafe_duration, &failsafe_duration_ms); + failsafe_duration_ms = failsafe_duration_ms / NSEC_PER_MSEC; + + absolutetime_to_nanoseconds(thread_usage, &thread_usage_ms); + thread_usage_ms = thread_usage_ms / NSEC_PER_MSEC; + + printf("recommended core failsafe kicked in for %lld ms " + "likely due to %s[%d] thread 0x%llx spending " + "%lld ms on cpu at realtime priority - " + "new recommendation: 0x%x -> 0x%x\n", + failsafe_duration_ms, p_name, pid, tid, thread_usage_ms, + rec_cores_before, rec_cores_after); + } +} /* - * do_thread_scan: scan for stuck threads. A thread is stuck if - * it is runnable but its priority is so low that it has not - * run for several seconds. Its priority should be higher, but - * won't be until it runs and calls update_priority. The scanner - * finds these threads and does the updates. + * Apply a new recommended cores mask to the processors it affects + * Runs after considering failsafes and such * - * Scanner runs in two passes. Pass one squirrels likely - * thread ids away in an array (takes out references for them). - * Pass two does the priority updates. This is necessary because - * the run queue lock is required for the candidate scan, but - * cannot be held during updates. - * - * Array length should be enough so that restart isn't necessary, - * but restart logic is included. + * Iterate over processors and update their ->is_recommended field. + * If a processor is running, we let it drain out at its next + * quantum expiration or blocking point. If a processor is idle, there + * may be more work for it to do, so IPI it. * + * interrupts disabled, sched_recommended_cores_lock is held */ -thread_t stuck_threads[MAX_STUCK_THREADS]; -int stuck_count = 0; - -/* - * do_runq_scan is the guts of pass 1. It scans a runq for - * stuck threads. A boolean is returned indicating whether - * a retry is needed. - */ -boolean_t -do_runq_scan( - run_queue_t runq) +static void +sched_update_recommended_cores(uint32_t recommended_cores) { - register queue_t q; - register thread_t thread; - register int count; - spl_t s; - boolean_t result = FALSE; - - s = splsched(); - simple_lock(&runq->lock); - if ((count = runq->count) > 0) { - q = runq->queues + runq->highq; - while (count > 0) { - queue_iterate(q, thread, thread_t, links) { - if ( !(thread->state & (TH_WAIT|TH_SUSP)) && - (thread->sched_mode & TH_MODE_TIMESHARE) ) { - if (thread->sched_stamp != sched_tick) { - /* - * Stuck, save its id for later. - */ - if (stuck_count == MAX_STUCK_THREADS) { - /* - * !@#$% No more room. - */ - simple_unlock(&runq->lock); - splx(s); - - return (TRUE); - } + processor_set_t pset, nset; + processor_t processor; + uint64_t needs_exit_idle_mask = 0x0; - /* - * Inline version of thread_reference - * XXX - lock ordering problem here: - * thread locks should be taken before runq - * locks: just try and get the thread's locks - * and ignore this thread if we fail, we might - * have better luck next time. - */ - if (thread_lock_try(thread)) { - thread->ref_count++; - thread_unlock(thread); - stuck_threads[stuck_count++] = thread; - } - else - result = TRUE; - } - } + processor = processor_list; + pset = processor->processor_set; - count--; - } + KDBG(MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED_UPDATE_REC_CORES) | DBG_FUNC_START, + recommended_cores, perfcontrol_failsafe_active, 0, 0); - q--; - } + if (__builtin_popcount(recommended_cores) == 0) { + bit_set(recommended_cores, master_processor->cpu_id); /* add boot processor or we hang */ } - simple_unlock(&runq->lock); - splx(s); - return (result); -} + /* First set recommended cores */ + pset_lock(pset); + do { -boolean_t thread_scan_enabled = TRUE; + nset = processor->processor_set; + if (nset != pset) { + pset_unlock(pset); + pset = nset; + pset_lock(pset); + } -void -do_thread_scan(void) -{ - register boolean_t restart_needed = FALSE; - register thread_t thread; - register processor_set_t pset = &default_pset; - register processor_t processor; - spl_t s; + if (bit_test(recommended_cores, processor->cpu_id)) { + processor->is_recommended = TRUE; + bit_set(pset->recommended_bitmask, processor->cpu_id); - if (!thread_scan_enabled) - return; + if (processor->state == PROCESSOR_IDLE) { + if (processor != current_processor()) { + bit_set(needs_exit_idle_mask, processor->cpu_id); + } + } + } + } while ((processor = processor->processor_list) != NULL); + pset_unlock(pset); + /* Now shutdown not recommended cores */ + processor = processor_list; + pset = processor->processor_set; + + pset_lock(pset); do { - restart_needed = do_runq_scan(&pset->runq); - if (!restart_needed) { - simple_lock(&pset->processors_lock); - processor = (processor_t)queue_first(&pset->processors); - while (!queue_end(&pset->processors, (queue_entry_t)processor)) { - if (restart_needed = do_runq_scan(&processor->runq)) - break; - thread = processor->idle_thread; - if (thread->sched_stamp != sched_tick) { - if (stuck_count == MAX_STUCK_THREADS) { - restart_needed = TRUE; - break; - } + nset = processor->processor_set; + if (nset != pset) { + pset_unlock(pset); + pset = nset; + pset_lock(pset); + } - stuck_threads[stuck_count++] = thread; - } + if (!bit_test(recommended_cores, processor->cpu_id)) { + sched_ipi_type_t ipi_type = SCHED_IPI_NONE; + + processor->is_recommended = FALSE; + bit_clear(pset->recommended_bitmask, processor->cpu_id); - processor = (processor_t)queue_next(&processor->processors); + if ((processor->state == PROCESSOR_RUNNING) || (processor->state == PROCESSOR_DISPATCHING)) { + ipi_type = SCHED_IPI_IMMEDIATE; } - simple_unlock(&pset->processors_lock); - } + SCHED(processor_queue_shutdown)(processor); + /* pset unlocked */ - /* - * Ok, we now have a collection of candidates -- fix them. - */ - while (stuck_count > 0) { - thread = stuck_threads[--stuck_count]; - stuck_threads[stuck_count] = THREAD_NULL; - s = splsched(); - thread_lock(thread); - if ( (thread->sched_mode & TH_MODE_TIMESHARE) || - (thread->state & TH_IDLE) ) { - if ( !(thread->state & (TH_WAIT|TH_SUSP)) && - thread->sched_stamp != sched_tick ) - update_priority(thread); + SCHED(rt_queue_shutdown)(processor); + + if (ipi_type != SCHED_IPI_NONE) { + if (processor == current_processor()) { + ast_on(AST_PREEMPT); + } else { + sched_ipi_perform(processor, ipi_type); + } } - thread_unlock(thread); - splx(s); - if (!(thread->state & TH_IDLE)) - thread_deallocate(thread); - } - if (restart_needed) - delay(1); /* XXX */ - - } while (restart_needed); + pset_lock(pset); + } + } while ((processor = processor->processor_list) != NULL); + pset_unlock(pset); + + /* Issue all pending IPIs now that the pset lock has been dropped */ + for (int cpuid = lsb_first(needs_exit_idle_mask); cpuid >= 0; cpuid = lsb_next(needs_exit_idle_mask, cpuid)) { + processor = processor_array[cpuid]; + machine_signal_idle(processor); + } + + KDBG(MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED_UPDATE_REC_CORES) | DBG_FUNC_END, + needs_exit_idle_mask, 0, 0, 0); } - -/* - * Just in case someone doesn't use the macro - */ -#undef thread_wakeup -void -thread_wakeup( - event_t x); +#endif /* __arm__ || __arm64__ */ -void -thread_wakeup( - event_t x) +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); +} + +void thread_set_pending_block_hint(thread_t thread, block_hint_t block_hint) { + thread->pending_block_hint = block_hint; +} + +uint32_t qos_max_parallelism(int qos, uint64_t options) { - thread_wakeup_with_result(x, THREAD_AWAKENED); + return SCHED(qos_max_parallelism)(qos, options); } +uint32_t sched_qos_max_parallelism(__unused int qos, uint64_t options) +{ + host_basic_info_data_t hinfo; + mach_msg_type_number_t count = HOST_BASIC_INFO_COUNT; + /* Query the machine layer for core information */ + __assert_only kern_return_t kret = host_info(host_self(), HOST_BASIC_INFO, + (host_info_t)&hinfo, &count); + assert(kret == KERN_SUCCESS); + + /* We would not want multiple realtime threads running on the + * same physical core; even for SMT capable machines. + */ + if (options & QOS_PARALLELISM_REALTIME) { + return hinfo.physical_cpu; + } + + if (options & QOS_PARALLELISM_COUNT_LOGICAL) { + return hinfo.logical_cpu; + } else { + return hinfo.physical_cpu; + } +} -#if DEBUG +#if __arm64__ -static boolean_t -thread_runnable( - thread_t thread) +/* + * Set up or replace old timer with new timer + * + * Returns true if canceled old timer, false if it did not + */ +boolean_t +sched_perfcontrol_update_callback_deadline(uint64_t new_deadline) { - return ((thread->state & (TH_RUN|TH_WAIT)) == TH_RUN); + /* + * Exchange deadline for new deadline, if old deadline was nonzero, + * then I cancelled the callback, otherwise I didn't + */ + + uint64_t old_deadline = __c11_atomic_load(&sched_perfcontrol_callback_deadline, + memory_order_relaxed); + + + while (!__c11_atomic_compare_exchange_weak(&sched_perfcontrol_callback_deadline, + &old_deadline, new_deadline, + memory_order_relaxed, memory_order_relaxed)); + + + /* now old_deadline contains previous value, which might not be the same if it raced */ + + return (old_deadline != 0) ? TRUE : FALSE; } -void -dump_processor_set( - processor_set_t ps) -{ - printf("processor_set: %08x\n",ps); - printf("idle_queue: %08x %08x, idle_count: 0x%x\n", - ps->idle_queue.next,ps->idle_queue.prev,ps->idle_count); - printf("processors: %08x %08x, processor_count: 0x%x\n", - ps->processors.next,ps->processors.prev,ps->processor_count); - printf("tasks: %08x %08x, task_count: 0x%x\n", - ps->tasks.next,ps->tasks.prev,ps->task_count); - printf("threads: %08x %08x, thread_count: 0x%x\n", - ps->threads.next,ps->threads.prev,ps->thread_count); - printf("ref_count: 0x%x, active: %x\n", - ps->ref_count,ps->active); - printf("pset_self: %08x, pset_name_self: %08x\n",ps->pset_self, ps->pset_name_self); - printf("set_quanta: 0x%x\n", ps->set_quanta); -} - -#define processor_state(s) (((s)>PROCESSOR_SHUTDOWN)?"*unknown*":states[s]) +#endif /* __arm64__ */ void -dump_processor( - processor_t p) +sched_update_pset_load_average(processor_set_t pset) { - char *states[]={"OFF_LINE","RUNNING","IDLE","DISPATCHING", - "ASSIGN","SHUTDOWN"}; + int load = ((bit_count(pset->cpu_state_map[PROCESSOR_RUNNING]) + pset->pset_runq.count + rt_runq_count(pset)) << PSET_LOAD_NUMERATOR_SHIFT); + int new_load_average = (pset->load_average + load) >> 1; - printf("processor: %08x\n",p); - printf("processor_queue: %08x %08x\n", - p->processor_queue.next,p->processor_queue.prev); - printf("state: %8s, next_thread: %08x, idle_thread: %08x\n", - processor_state(p->state), p->next_thread, p->idle_thread); - printf("slice_quanta: %x\n", p->slice_quanta); - printf("processor_set: %08x, processor_set_next: %08x\n", - p->processor_set, p->processor_set_next); - printf("processors: %08x %08x\n", p->processors.next,p->processors.prev); - printf("processor_self: %08x, slot_num: 0x%x\n", p->processor_self, p->slot_num); + pset->load_average = new_load_average; + +#if (DEVELOPMENT || DEBUG) +#endif } -void -dump_run_queue_struct( - run_queue_t rq) +/* pset is locked */ +static processor_t +choose_processor_for_realtime_thread(processor_set_t pset) { - char dump_buf[80]; - int i; + uint64_t cpu_map = (pset->cpu_bitmask & pset->recommended_bitmask & ~pset->pending_AST_cpu_mask); - for( i=0; i < NRQS; ) { - int j; + for (int cpuid = lsb_first(cpu_map); cpuid >= 0; cpuid = lsb_next(cpu_map, cpuid)) { + processor_t processor = processor_array[cpuid]; - printf("%6s",(i==0)?"runq:":""); - for( j=0; (j<8) && (i < NRQS); j++,i++ ) { - if( rq->queues[i].next == &rq->queues[i] ) - printf( " --------"); - else - printf(" %08x",rq->queues[i].next); - } - printf("\n"); - } - for( i=0; i < NRQBM; ) { - register unsigned int mask; - char *d=dump_buf; + if (processor->processor_primary != processor) { + continue; + } - mask = ~0; - mask ^= (mask>>1); + if (processor->state == PROCESSOR_IDLE) { + return processor; + } + + if ((processor->state != PROCESSOR_RUNNING) && (processor->state != PROCESSOR_DISPATCHING)) { + continue; + } + + if (processor->current_pri >= BASEPRI_RTQUEUES) { + continue; + } + + return processor; - do { - *d++ = ((rq->bitmap[i]&mask)?'r':'e'); - mask >>=1; - } while( mask ); - *d = '\0'; - printf("%8s%s\n",((i==0)?"bitmap:":""),dump_buf); - i++; - } - printf("highq: 0x%x, count: %u\n", rq->highq, rq->count); -} - -void -dump_run_queues( - run_queue_t runq) -{ - register queue_t q1; - register int i; - register queue_entry_t e; - - q1 = runq->queues; - for (i = 0; i < NRQS; i++) { - if (q1->next != q1) { - int t_cnt; - - printf("[%u]",i); - for (t_cnt=0, e = q1->next; e != q1; e = e->next) { - printf("\t0x%08x",e); - if( (t_cnt = ++t_cnt%4) == 0 ) - printf("\n"); - } - if( t_cnt ) - printf("\n"); - } - /* else - printf("[%u]\t\n",i); - */ - q1++; } -} -void -checkrq( - run_queue_t rq, - char *msg) -{ - register queue_t q1; - register int i, j; - register queue_entry_t e; - register int highq; - - highq = NRQS; - j = 0; - q1 = rq->queues; - for (i = MAXPRI; i >= 0; i--) { - if (q1->next == q1) { - if (q1->prev != q1) { - panic("checkrq: empty at %s", msg); - } - } - else { - if (highq == -1) - highq = i; - - for (e = q1->next; e != q1; e = e->next) { - j++; - if (e->next->prev != e) - panic("checkrq-2 at %s", msg); - if (e->prev->next != e) - panic("checkrq-3 at %s", msg); + if (!sched_allow_rt_smt) { + return PROCESSOR_NULL; + } + + /* Consider secondary processors */ + for (int cpuid = lsb_first(cpu_map); cpuid >= 0; cpuid = lsb_next(cpu_map, cpuid)) { + processor_t processor = processor_array[cpuid]; + + if (processor->processor_primary == processor) { + continue; } - } - q1++; + + if (processor->state == PROCESSOR_IDLE) { + return processor; + } + + if ((processor->state != PROCESSOR_RUNNING) && (processor->state != PROCESSOR_DISPATCHING)) { + continue; + } + + if (processor->current_pri >= BASEPRI_RTQUEUES) { + continue; + } + + return processor; + } - if (j != rq->count) - panic("checkrq: count wrong at %s", msg); - if (rq->count != 0 && highq > rq->highq) - panic("checkrq: highq wrong at %s", msg); + + return PROCESSOR_NULL; } -void -thread_check( - register thread_t thread, - register run_queue_t rq) +/* pset is locked */ +static bool +all_available_primaries_are_running_realtime_threads(processor_set_t pset) { - register int whichq = thread->sched_pri; - register queue_entry_t queue, entry; + uint64_t cpu_map = (pset->cpu_bitmask & pset->recommended_bitmask); - if (whichq < MINPRI || whichq > MAXPRI) - panic("thread_check: bad pri"); + for (int cpuid = lsb_first(cpu_map); cpuid >= 0; cpuid = lsb_next(cpu_map, cpuid)) { + processor_t processor = processor_array[cpuid]; - queue = &rq->queues[whichq]; - entry = queue_first(queue); - while (!queue_end(queue, entry)) { - if (entry == (queue_entry_t)thread) - return; + if (processor->processor_primary != processor) { + continue; + } + + if (processor->state == PROCESSOR_IDLE) { + return false; + } + + if (processor->state == PROCESSOR_DISPATCHING) { + return false; + } + + if (processor->state != PROCESSOR_RUNNING) { + /* + * All other processor states are considered unavailable to run + * realtime threads. In particular, we prefer an available secondary + * processor over the risk of leaving a realtime thread on the run queue + * while waiting for a processor in PROCESSOR_START state, + * which should anyway be a rare case. + */ + continue; + } - entry = queue_next(entry); + if (processor->current_pri < BASEPRI_RTQUEUES) { + return false; + } } - panic("thread_check: not found"); + return true; } -#endif /* DEBUG */ -#if MACH_KDB -#include -#define printf kdbprintf -extern int db_indent; -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; -} -#endif /* MACH_KDB */