/*
* Copyright (c) 2000-2019 Apple 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. 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
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* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
/*
* @OSF_COPYRIGHT@
*/
/*
* Mach Operating System
* Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/
/*
*/
/*
* File: priority.c
* Author: Avadis Tevanian, Jr.
* Date: 1986
*
* Priority related scheduler bits.
*/
#include <mach/boolean.h>
#include <mach/kern_return.h>
#include <mach/machine.h>
#include <kern/host.h>
#include <kern/mach_param.h>
#include <kern/sched.h>
#include <sys/kdebug.h>
#include <kern/spl.h>
#include <kern/thread.h>
#include <kern/processor.h>
#include <kern/ledger.h>
#include <kern/monotonic.h>
#include <machine/machparam.h>
#include <kern/machine.h>
#include <kern/policy_internal.h>
#include <kern/sched_clutch.h>
#ifdef CONFIG_MACH_APPROXIMATE_TIME
#include <machine/commpage.h> /* for commpage_update_mach_approximate_time */
#endif
/*
* thread_quantum_expire:
*
* Recalculate the quantum and priority for a thread.
*
* Called at splsched.
*/
void
thread_quantum_expire(
timer_call_param_t p0,
timer_call_param_t p1)
{
processor_t processor = p0;
thread_t thread = p1;
ast_t preempt;
uint64_t ctime;
assert(processor == current_processor());
assert(thread == current_thread());
KDBG_RELEASE(MACHDBG_CODE(
DBG_MACH_SCHED, MACH_SCHED_QUANTUM_EXPIRED) | DBG_FUNC_START);
SCHED_STATS_INC(quantum_timer_expirations);
/*
* We bill CPU time to both the individual thread and its task.
*
* Because this balance adjustment could potentially attempt to wake this
* very thread, we must credit the ledger before taking the thread lock.
* The ledger pointers are only manipulated by the thread itself at the ast
* boundary.
*
* TODO: This fails to account for the time between when the timer was
* armed and when it fired. It should be based on the system_timer and
* running a timer_update operation here.
*/
ledger_credit(thread->t_ledger, task_ledgers.cpu_time, thread->quantum_remaining);
ledger_credit(thread->t_threadledger, thread_ledgers.cpu_time, thread->quantum_remaining);
if (thread->t_bankledger) {
ledger_credit(thread->t_bankledger, bank_ledgers.cpu_time,
(thread->quantum_remaining - thread->t_deduct_bank_ledger_time));
}
thread->t_deduct_bank_ledger_time = 0;
struct recount_snap snap = { 0 };
recount_snapshot(&snap);
ctime = snap.rsn_time_mach;
check_monotonic_time(ctime);
#ifdef CONFIG_MACH_APPROXIMATE_TIME
commpage_update_mach_approximate_time(ctime);
#endif /* CONFIG_MACH_APPROXIMATE_TIME */
sched_update_pset_avg_execution_time(processor->processor_set, thread->quantum_remaining, ctime, thread->th_sched_bucket);
recount_switch_thread(&snap, thread, get_threadtask(thread));
recount_log_switch_thread(&snap);
thread_lock(thread);
/*
* We've run up until our quantum expiration, and will (potentially)
* continue without re-entering the scheduler, so update this now.
*/
processor->last_dispatch = ctime;
thread->last_run_time = ctime;
/*
* Check for fail-safe trip.
*/
if ((thread->sched_mode == TH_MODE_REALTIME || thread->sched_mode == TH_MODE_FIXED) &&
!(thread->sched_flags & TH_SFLAG_PROMOTED) &&
!(thread->kern_promotion_schedpri != 0) &&
!(thread->sched_flags & TH_SFLAG_PROMOTE_REASON_MASK) &&
!(thread->options & TH_OPT_SYSTEM_CRITICAL)) {
uint64_t new_computation;
new_computation = ctime - thread->computation_epoch;
new_computation += thread->computation_metered;
/*
* Remove any time spent handling interrupts outside of the thread's
* control.
*/
new_computation -= recount_current_thread_interrupt_time_mach() - thread->computation_interrupt_epoch;
bool demote = false;
switch (thread->sched_mode) {
case TH_MODE_REALTIME:
if (new_computation > max_unsafe_rt_computation) {
thread->safe_release = ctime + sched_safe_rt_duration;
demote = true;
}
break;
case TH_MODE_FIXED:
if (new_computation > max_unsafe_fixed_computation) {
thread->safe_release = ctime + sched_safe_fixed_duration;
demote = true;
}
break;
default:
panic("unexpected mode: %d", thread->sched_mode);
}
if (demote) {
KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_FAILSAFE) | DBG_FUNC_NONE,
(uintptr_t)thread->sched_pri, (uintptr_t)thread->sched_mode, 0, 0, 0);
sched_thread_mode_demote(thread, TH_SFLAG_FAILSAFE);
}
}
/*
* Recompute scheduled priority if appropriate.
*/
if (SCHED(can_update_priority)(thread)) {
SCHED(update_priority)(thread);
} else {
SCHED(lightweight_update_priority)(thread);
}
if (thread->sched_mode != TH_MODE_REALTIME) {
SCHED(quantum_expire)(thread);
}
/*
* This quantum is up, give this thread another.
*/
processor->first_timeslice = FALSE;
thread_quantum_init(thread, ctime);
timer_update(&thread->runnable_timer, ctime);
processor->quantum_end = ctime + thread->quantum_remaining;
/*
* Context switch check
*
* non-urgent flags don't affect kernel threads, so upgrade to urgent
* to ensure that rebalancing and non-recommendation kick in quickly.
*/
ast_t check_reason = AST_QUANTUM;
if (get_threadtask(thread) == kernel_task) {
check_reason |= AST_URGENT;
}
if ((preempt = csw_check(thread, processor, check_reason)) != AST_NONE) {
ast_on(preempt);
}
/*
* AST_KEVENT does not send an IPI when setting the AST,
* to avoid waiting for the next context switch to propagate the AST,
* the AST is propagated here at quantum expiration.
*/
ast_propagate(thread);
thread_unlock(thread);
/* Now that the processor->thread_timer has been updated, evaluate to see if
* the workqueue quantum expired and set AST_KEVENT if it has */
if (thread_get_tag(thread) & THREAD_TAG_WORKQUEUE) {
thread_evaluate_workqueue_quantum_expiry(thread);
}
running_timer_enter(processor, RUNNING_TIMER_QUANTUM, thread,
processor->quantum_end, ctime);
/* Tell platform layer that we are still running this thread */
thread_urgency_t urgency = thread_get_urgency(thread, NULL, NULL);
machine_thread_going_on_core(thread, urgency, 0, 0, ctime);
machine_switch_perfcontrol_state_update(QUANTUM_EXPIRY, ctime,
0, thread);
#if defined(CONFIG_SCHED_TIMESHARE_CORE)
sched_timeshare_consider_maintenance(ctime, false);
#endif /* CONFIG_SCHED_TIMESHARE_CORE */
#if __arm64__
if (thread->sched_mode == TH_MODE_REALTIME) {
sched_consider_recommended_cores(ctime, thread);
}
#endif /* __arm64__ */
KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_QUANTUM_EXPIRED) | DBG_FUNC_END, preempt, 0, 0, 0, 0);
}
/*
* sched_set_thread_base_priority:
*
* Set the base priority of the thread
* and reset its scheduled priority.
*
* This is the only path to change base_pri.
*
* Called with the thread locked.
*/
void
sched_set_thread_base_priority(thread_t thread, int priority)
{
assert(priority >= MINPRI);
uint64_t ctime = 0;
if (thread->sched_mode == TH_MODE_REALTIME) {
assert((priority >= BASEPRI_RTQUEUES) && (priority <= MAXPRI));
} else {
assert(priority < BASEPRI_RTQUEUES);
}
int old_base_pri = thread->base_pri;
thread->req_base_pri = (int16_t)priority;
if (thread->sched_flags & TH_SFLAG_BASE_PRI_FROZEN) {
priority = MAX(priority, old_base_pri);
}
thread->base_pri = (int16_t)priority;
if ((thread->state & TH_RUN) == TH_RUN) {
assert(thread->last_made_runnable_time != THREAD_NOT_RUNNABLE);
ctime = mach_approximate_time();
thread->last_basepri_change_time = ctime;
} else {
assert(thread->last_basepri_change_time == THREAD_NOT_RUNNABLE);
assert(thread->last_made_runnable_time == THREAD_NOT_RUNNABLE);
}
/*
* Currently the perfcontrol_attr depends on the base pri of the
* thread. Therefore, we use this function as the hook for the
* perfcontrol callout.
*/
if (thread == current_thread() && old_base_pri != priority) {
if (!ctime) {
ctime = mach_approximate_time();
}
machine_switch_perfcontrol_state_update(PERFCONTROL_ATTR_UPDATE,
ctime, PERFCONTROL_CALLOUT_WAKE_UNSAFE, thread);
}
#if !CONFIG_SCHED_CLUTCH
/* For the clutch scheduler, this operation is done in set_sched_pri() */
SCHED(update_thread_bucket)(thread);
#endif /* !CONFIG_SCHED_CLUTCH */
thread_recompute_sched_pri(thread, SETPRI_DEFAULT);
}
/*
* sched_set_kernel_thread_priority:
*
* Set the absolute base priority of the thread
* and reset its scheduled priority.
*
* Called with the thread unlocked.
*/
void
sched_set_kernel_thread_priority(thread_t thread, int new_priority)
{
spl_t s = splsched();
thread_lock(thread);
assert(thread->sched_mode != TH_MODE_REALTIME);
assert(thread->effective_policy.thep_qos == THREAD_QOS_UNSPECIFIED);
if (new_priority > thread->max_priority) {
new_priority = thread->max_priority;
}
#if !defined(XNU_TARGET_OS_OSX)
if (new_priority < MAXPRI_THROTTLE) {
new_priority = MAXPRI_THROTTLE;
}
#endif /* !defined(XNU_TARGET_OS_OSX) */
thread->importance = new_priority - thread->task_priority;
sched_set_thread_base_priority(thread, new_priority);
thread_unlock(thread);
splx(s);
}
/*
* thread_recompute_sched_pri:
*
* Reset the scheduled priority of the thread
* according to its base priority if the
* thread has not been promoted or depressed.
*
* This is the only way to push base_pri changes into sched_pri,
* or to recalculate the appropriate sched_pri after changing
* a promotion or depression.
*
* Called at splsched with the thread locked.
*
* TODO: Add an 'update urgency' flag to avoid urgency callouts on every rwlock operation
*/
void
thread_recompute_sched_pri(thread_t thread, set_sched_pri_options_t options)
{
uint32_t sched_flags = thread->sched_flags;
sched_mode_t sched_mode = thread->sched_mode;
int16_t priority = thread->base_pri;
if (sched_mode == TH_MODE_TIMESHARE) {
priority = (int16_t)SCHED(compute_timeshare_priority)(thread);
}
if (sched_flags & TH_SFLAG_DEPRESS) {
/* thread_yield_internal overrides kernel mutex promotion */
priority = DEPRESSPRI;
} else {
/* poll-depress is overridden by mutex promotion and promote-reasons */
if ((sched_flags & TH_SFLAG_POLLDEPRESS)) {
priority = DEPRESSPRI;
}
if (thread->kern_promotion_schedpri > 0) {
priority = MAX(priority, thread->kern_promotion_schedpri);
if (sched_mode != TH_MODE_REALTIME) {
priority = MIN(priority, MAXPRI_PROMOTE);
}
}
if (sched_flags & TH_SFLAG_PROMOTED) {
priority = MAX(priority, thread->promotion_priority);
if (sched_mode != TH_MODE_REALTIME) {
priority = MIN(priority, MAXPRI_PROMOTE);
}
}
if (sched_flags & TH_SFLAG_PROMOTE_REASON_MASK) {
if (sched_flags & TH_SFLAG_RW_PROMOTED) {
priority = MAX(priority, MINPRI_RWLOCK);
}
if (sched_flags & TH_SFLAG_WAITQ_PROMOTED) {
priority = MAX(priority, MINPRI_WAITQ);
}
if (sched_flags & TH_SFLAG_EXEC_PROMOTED) {
priority = MAX(priority, MINPRI_EXEC);
}
if (sched_flags & TH_SFLAG_FLOOR_PROMOTED) {
priority = MAX(priority, MINPRI_FLOOR);
}
}
}
set_sched_pri(thread, priority, options);
}
void
sched_default_quantum_expire(thread_t thread __unused)
{
/*
* No special behavior when a timeshare, fixed, or realtime thread
* uses up its entire quantum
*/
}
int smt_timeshare_enabled = 1;
int smt_sched_bonus_16ths = 8;
#if defined(CONFIG_SCHED_TIMESHARE_CORE)
/*
* lightweight_update_priority:
*
* Update the scheduled priority for
* a timesharing thread.
*
* Only for use on the current thread.
*
* Called with the thread locked.
*/
void
lightweight_update_priority(thread_t thread)
{
thread_assert_runq_null(thread);
assert(thread == current_thread());
if (thread->sched_mode == TH_MODE_TIMESHARE) {
int priority;
uint32_t delta;
sched_tick_delta(thread, delta);
/*
* Accumulate timesharing usage only
* during contention for processor
* resources.
*/
if (thread->pri_shift < INT8_MAX) {
if (thread_no_smt(thread) && smt_timeshare_enabled) {
thread->sched_usage += (delta + ((delta * smt_sched_bonus_16ths) >> 4));
} else {
thread->sched_usage += delta;
}
}
thread->cpu_delta += delta;
#if CONFIG_SCHED_CLUTCH
/*
* Update the CPU usage for the thread group to which the thread belongs.
* The implementation assumes that the thread ran for the entire delta
* as part of the same thread group.
*/
sched_clutch_cpu_usage_update(thread, delta);
#endif /* CONFIG_SCHED_CLUTCH */
priority = sched_compute_timeshare_priority(thread);
if (priority != thread->sched_pri) {
thread_recompute_sched_pri(thread, SETPRI_LAZY);
}
}
}
/*
* Define shifts for simulating (5/8) ** n
*
* Shift structures for holding update shifts. Actual computation
* is usage = (usage >> shift1) +/- (usage >> abs(shift2)) where the
* +/- is determined by the sign of shift 2.
*/
const struct shift_data sched_decay_shifts[SCHED_DECAY_TICKS] = {
{ .shift1 = 1, .shift2 = 1 },
{ .shift1 = 1, .shift2 = 3 },
{ .shift1 = 1, .shift2 = -3 },
{ .shift1 = 2, .shift2 = -7 },
{ .shift1 = 3, .shift2 = 5 },
{ .shift1 = 3, .shift2 = -5 },
{ .shift1 = 4, .shift2 = -8 },
{ .shift1 = 5, .shift2 = 7 },
{ .shift1 = 5, .shift2 = -7 },
{ .shift1 = 6, .shift2 = -10 },
{ .shift1 = 7, .shift2 = 10 },
{ .shift1 = 7, .shift2 = -9 },
{ .shift1 = 8, .shift2 = -11 },
{ .shift1 = 9, .shift2 = 12 },
{ .shift1 = 9, .shift2 = -11 },
{ .shift1 = 10, .shift2 = -13 },
{ .shift1 = 11, .shift2 = 14 },
{ .shift1 = 11, .shift2 = -13 },
{ .shift1 = 12, .shift2 = -15 },
{ .shift1 = 13, .shift2 = 17 },
{ .shift1 = 13, .shift2 = -15 },
{ .shift1 = 14, .shift2 = -17 },
{ .shift1 = 15, .shift2 = 19 },
{ .shift1 = 16, .shift2 = 18 },
{ .shift1 = 16, .shift2 = -19 },
{ .shift1 = 17, .shift2 = 22 },
{ .shift1 = 18, .shift2 = 20 },
{ .shift1 = 18, .shift2 = -20 },
{ .shift1 = 19, .shift2 = 26 },
{ .shift1 = 20, .shift2 = 22 },
{ .shift1 = 20, .shift2 = -22 },
{ .shift1 = 21, .shift2 = -27 }
};
/*
* sched_compute_timeshare_priority:
*
* Calculate the timesharing priority based upon usage and load.
*/
extern int sched_pri_decay_band_limit;
/* Only use the decay floor logic on non-macOS and non-clutch schedulers */
#if !defined(XNU_TARGET_OS_OSX) && !CONFIG_SCHED_CLUTCH
int
sched_compute_timeshare_priority(thread_t thread)
{
int decay_amount;
int decay_limit = sched_pri_decay_band_limit;
if (thread->base_pri > BASEPRI_FOREGROUND) {
decay_limit += (thread->base_pri - BASEPRI_FOREGROUND);
}
if (thread->pri_shift == INT8_MAX) {
decay_amount = 0;
} else {
decay_amount = (thread->sched_usage >> thread->pri_shift);
}
if (decay_amount > decay_limit) {
decay_amount = decay_limit;
}
/* start with base priority */
int priority = thread->base_pri - decay_amount;
if (priority < MAXPRI_THROTTLE) {
if (get_threadtask(thread)->max_priority > MAXPRI_THROTTLE) {
priority = MAXPRI_THROTTLE;
} else if (priority < MINPRI_USER) {
priority = MINPRI_USER;
}
} else if (priority > MAXPRI_KERNEL) {
priority = MAXPRI_KERNEL;
}
return priority;
}
#else /* !defined(XNU_TARGET_OS_OSX) && !CONFIG_SCHED_CLUTCH */
int
sched_compute_timeshare_priority(thread_t thread)
{
/* start with base priority */
int priority = thread->base_pri;
if (thread->pri_shift != INT8_MAX) {
priority -= (thread->sched_usage >> thread->pri_shift);
}
if (priority < MINPRI_USER) {
priority = MINPRI_USER;
} else if (priority > MAXPRI_KERNEL) {
priority = MAXPRI_KERNEL;
}
return priority;
}
#endif /* !defined(XNU_TARGET_OS_OSX) && !CONFIG_SCHED_CLUTCH */
/*
* can_update_priority
*
* Make sure we don't do re-dispatches more frequently than a scheduler tick.
*
* Called with the thread locked.
*/
boolean_t
can_update_priority(
thread_t thread)
{
if (sched_tick == thread->sched_stamp) {
return FALSE;
} else {
return TRUE;
}
}
/*
* update_priority
*
* Perform housekeeping operations driven by scheduler tick.
*
* Called with the thread locked.
*/
void
update_priority(
thread_t thread)
{
uint32_t ticks, delta;
ticks = sched_tick - thread->sched_stamp;
assert(ticks != 0);
thread->sched_stamp += ticks;
/* If requested, accelerate aging of sched_usage */
if (sched_decay_usage_age_factor > 1) {
ticks *= sched_decay_usage_age_factor;
}
/*
* Gather cpu usage data.
*/
sched_tick_delta(thread, delta);
if (ticks < SCHED_DECAY_TICKS) {
/*
* Accumulate timesharing usage only during contention for processor
* resources. Use the pri_shift from the previous tick window to
* determine if the system was in a contended state.
*/
if (thread->pri_shift < INT8_MAX) {
if (thread_no_smt(thread) && smt_timeshare_enabled) {
thread->sched_usage += (delta + ((delta * smt_sched_bonus_16ths) >> 4));
} else {
thread->sched_usage += delta;
}
}
thread->cpu_usage += delta + thread->cpu_delta;
thread->cpu_delta = 0;
#if CONFIG_SCHED_CLUTCH
/*
* Update the CPU usage for the thread group to which the thread belongs.
* The implementation assumes that the thread ran for the entire delta
* as part of the same thread group.
*/
sched_clutch_cpu_usage_update(thread, delta);
#endif /* CONFIG_SCHED_CLUTCH */
const struct shift_data *shiftp = &sched_decay_shifts[ticks];
if (shiftp->shift2 > 0) {
thread->cpu_usage = (thread->cpu_usage >> shiftp->shift1) +
(thread->cpu_usage >> shiftp->shift2);
thread->sched_usage = (thread->sched_usage >> shiftp->shift1) +
(thread->sched_usage >> shiftp->shift2);
} else {
thread->cpu_usage = (thread->cpu_usage >> shiftp->shift1) -
(thread->cpu_usage >> -(shiftp->shift2));
thread->sched_usage = (thread->sched_usage >> shiftp->shift1) -
(thread->sched_usage >> -(shiftp->shift2));
}
} else {
thread->cpu_usage = thread->cpu_delta = 0;
thread->sched_usage = 0;
}
/*
* Check for fail-safe release.
*/
if ((thread->sched_flags & TH_SFLAG_FAILSAFE) &&
mach_absolute_time() >= thread->safe_release) {
sched_thread_mode_undemote(thread, TH_SFLAG_FAILSAFE);
}
/*
* Now that the thread's CPU usage has been accumulated and aged
* based on contention of the previous tick window, update the
* pri_shift of the thread to match the current global load/shift
* values. The updated pri_shift would be used to calculate the
* new priority of the thread.
*/
#if CONFIG_SCHED_CLUTCH
thread->pri_shift = sched_clutch_thread_pri_shift(thread, thread->th_sched_bucket);
#else /* CONFIG_SCHED_CLUTCH */
thread->pri_shift = sched_pri_shifts[thread->th_sched_bucket];
#endif /* CONFIG_SCHED_CLUTCH */
/* Recompute scheduled priority if appropriate. */
if (thread->sched_mode == TH_MODE_TIMESHARE) {
thread_recompute_sched_pri(thread, SETPRI_LAZY);
}
}
#endif /* CONFIG_SCHED_TIMESHARE_CORE */
/*
* TH_BUCKET_RUN is a count of *all* runnable non-idle threads.
* Each other bucket is a count of the runnable non-idle threads
* with that property. All updates to these counts should be
* performed with os_atomic_* operations.
*
* For the clutch scheduler, this global bucket is used only for
* keeping the total global run count.
*/
uint32_t sched_run_buckets[TH_BUCKET_MAX];
static void
sched_incr_bucket(sched_bucket_t bucket)
{
assert(bucket >= TH_BUCKET_FIXPRI &&
bucket <= TH_BUCKET_SHARE_BG);
os_atomic_inc(&sched_run_buckets[bucket], relaxed);
}
static void
sched_decr_bucket(sched_bucket_t bucket)
{
assert(bucket >= TH_BUCKET_FIXPRI &&
bucket <= TH_BUCKET_SHARE_BG);
assert(os_atomic_load(&sched_run_buckets[bucket], relaxed) > 0);
os_atomic_dec(&sched_run_buckets[bucket], relaxed);
}
static void
sched_add_bucket(sched_bucket_t bucket, uint8_t run_weight)
{
assert(bucket >= TH_BUCKET_FIXPRI &&
bucket <= TH_BUCKET_SHARE_BG);
os_atomic_add(&sched_run_buckets[bucket], run_weight, relaxed);
}
static void
sched_sub_bucket(sched_bucket_t bucket, uint8_t run_weight)
{
assert(bucket >= TH_BUCKET_FIXPRI &&
bucket <= TH_BUCKET_SHARE_BG);
assert(os_atomic_load(&sched_run_buckets[bucket], relaxed) > 0);
os_atomic_sub(&sched_run_buckets[bucket], run_weight, relaxed);
}
uint32_t
sched_run_incr(thread_t thread)
{
assert((thread->state & (TH_RUN | TH_IDLE)) == TH_RUN);
uint32_t new_count = os_atomic_inc(&sched_run_buckets[TH_BUCKET_RUN], relaxed);
sched_incr_bucket(thread->th_sched_bucket);
return new_count;
}
uint32_t
sched_run_decr(thread_t thread)
{
assert((thread->state & (TH_RUN | TH_IDLE)) != TH_RUN);
sched_decr_bucket(thread->th_sched_bucket);
uint32_t new_count = os_atomic_dec(&sched_run_buckets[TH_BUCKET_RUN], relaxed);
return new_count;
}
uint32_t
sched_smt_run_incr(thread_t thread)
{
assert((thread->state & (TH_RUN | TH_IDLE)) == TH_RUN);
uint8_t run_weight = (thread_no_smt(thread) && smt_timeshare_enabled) ? 2 : 1;
thread->sched_saved_run_weight = run_weight;
uint32_t new_count = os_atomic_add(&sched_run_buckets[TH_BUCKET_RUN], run_weight, relaxed);
sched_add_bucket(thread->th_sched_bucket, run_weight);
return new_count;
}
uint32_t
sched_smt_run_decr(thread_t thread)
{
assert((thread->state & (TH_RUN | TH_IDLE)) != TH_RUN);
uint8_t run_weight = thread->sched_saved_run_weight;
sched_sub_bucket(thread->th_sched_bucket, run_weight);
uint32_t new_count = os_atomic_sub(&sched_run_buckets[TH_BUCKET_RUN], run_weight, relaxed);
return new_count;
}
void
sched_update_thread_bucket(thread_t thread)
{
sched_bucket_t old_bucket = thread->th_sched_bucket;
sched_bucket_t new_bucket = TH_BUCKET_RUN;
switch (thread->sched_mode) {
case TH_MODE_FIXED:
case TH_MODE_REALTIME:
new_bucket = TH_BUCKET_FIXPRI;
break;
case TH_MODE_TIMESHARE:
if (thread->base_pri > BASEPRI_DEFAULT) {
new_bucket = TH_BUCKET_SHARE_FG;
} else if (thread->base_pri > BASEPRI_UTILITY) {
new_bucket = TH_BUCKET_SHARE_DF;
} else if (thread->base_pri > MAXPRI_THROTTLE) {
new_bucket = TH_BUCKET_SHARE_UT;
} else {
new_bucket = TH_BUCKET_SHARE_BG;
}
break;
default:
panic("unexpected mode: %d", thread->sched_mode);
break;
}
if (old_bucket != new_bucket) {
thread->th_sched_bucket = new_bucket;
thread->pri_shift = sched_pri_shifts[new_bucket];
if ((thread->state & (TH_RUN | TH_IDLE)) == TH_RUN) {
sched_decr_bucket(old_bucket);
sched_incr_bucket(new_bucket);
}
}
}
void
sched_smt_update_thread_bucket(thread_t thread)
{
sched_bucket_t old_bucket = thread->th_sched_bucket;
sched_bucket_t new_bucket = TH_BUCKET_RUN;
switch (thread->sched_mode) {
case TH_MODE_FIXED:
case TH_MODE_REALTIME:
new_bucket = TH_BUCKET_FIXPRI;
break;
case TH_MODE_TIMESHARE:
if (thread->base_pri > BASEPRI_DEFAULT) {
new_bucket = TH_BUCKET_SHARE_FG;
} else if (thread->base_pri > BASEPRI_UTILITY) {
new_bucket = TH_BUCKET_SHARE_DF;
} else if (thread->base_pri > MAXPRI_THROTTLE) {
new_bucket = TH_BUCKET_SHARE_UT;
} else {
new_bucket = TH_BUCKET_SHARE_BG;
}
break;
default:
panic("unexpected mode: %d", thread->sched_mode);
break;
}
if (old_bucket != new_bucket) {
thread->th_sched_bucket = new_bucket;
thread->pri_shift = sched_pri_shifts[new_bucket];
if ((thread->state & (TH_RUN | TH_IDLE)) == TH_RUN) {
sched_sub_bucket(old_bucket, thread->sched_saved_run_weight);
sched_add_bucket(new_bucket, thread->sched_saved_run_weight);
}
}
}
static inline void
sched_validate_mode(sched_mode_t mode)
{
switch (mode) {
case TH_MODE_FIXED:
case TH_MODE_REALTIME:
case TH_MODE_TIMESHARE:
break;
default:
panic("unexpected mode: %d", mode);
break;
}
}
/*
* Set the thread's true scheduling mode
* Called with thread mutex and thread locked
* The thread has already been removed from the runqueue.
*
* (saved_mode is handled before this point)
*/
void
sched_set_thread_mode(thread_t thread, sched_mode_t new_mode)
{
thread_assert_runq_null(thread);
sched_validate_mode(new_mode);
#if CONFIG_SCHED_AUTO_JOIN
/*
* Realtime threads might have auto-joined a work interval based on
* make runnable relationships. If such an RT thread is now being demoted
* to non-RT, unjoin the thread from the work interval.
*/
if ((thread->sched_flags & TH_SFLAG_THREAD_GROUP_AUTO_JOIN) && (new_mode != TH_MODE_REALTIME)) {
assert((thread->sched_mode == TH_MODE_REALTIME) || (thread->th_work_interval_flags & TH_WORK_INTERVAL_FLAGS_AUTO_JOIN_LEAK));
work_interval_auto_join_demote(thread);
}
#endif /* CONFIG_SCHED_AUTO_JOIN */
thread->sched_mode = new_mode;
SCHED(update_thread_bucket)(thread);
}
/*
* TODO: Instead of having saved mode, have 'user mode' and 'true mode'.
* That way there's zero confusion over which the user wants
* and which the kernel wants.
*/
void
sched_set_thread_mode_user(thread_t thread, sched_mode_t new_mode)
{
thread_assert_runq_null(thread);
sched_validate_mode(new_mode);
/* If demoted, only modify the saved mode. */
if (thread->sched_flags & TH_SFLAG_DEMOTED_MASK) {
thread->saved_mode = new_mode;
} else {
sched_set_thread_mode(thread, new_mode);
}
}
sched_mode_t
sched_get_thread_mode_user(thread_t thread)
{
if (thread->sched_flags & TH_SFLAG_DEMOTED_MASK) {
return thread->saved_mode;
} else {
return thread->sched_mode;
}
}
/*
* Demote the true scheduler mode to timeshare (called with the thread locked)
*/
void
sched_thread_mode_demote(thread_t thread, uint32_t reason)
{
assert(reason & TH_SFLAG_DEMOTED_MASK);
assert((thread->sched_flags & reason) != reason);
if (thread->policy_reset) {
return;
}
switch (reason) {
case TH_SFLAG_THROTTLED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_MODE_DEMOTE_THROTTLED),
thread_tid(thread), thread->sched_flags);
break;
case TH_SFLAG_FAILSAFE:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_MODE_DEMOTE_FAILSAFE),
thread_tid(thread), thread->sched_flags);
break;
case TH_SFLAG_RT_DISALLOWED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_MODE_DEMOTE_RT_DISALLOWED),
thread_tid(thread), thread->sched_flags);
break;
}
if (thread->sched_flags & TH_SFLAG_DEMOTED_MASK) {
/* Another demotion reason is already active */
thread->sched_flags |= reason;
return;
}
assert(thread->saved_mode == TH_MODE_NONE);
boolean_t removed = thread_run_queue_remove(thread);
thread->sched_flags |= reason;
thread->saved_mode = thread->sched_mode;
sched_set_thread_mode(thread, TH_MODE_TIMESHARE);
thread_recompute_priority(thread);
if (removed) {
thread_run_queue_reinsert(thread, SCHED_TAILQ);
}
}
/*
* Return true if the thread is demoted for the specified reason
*/
bool
sched_thread_mode_has_demotion(thread_t thread, uint32_t reason)
{
assert(reason & TH_SFLAG_DEMOTED_MASK);
return (thread->sched_flags & reason) != 0;
}
/*
* Un-demote the true scheduler mode back to the saved mode (called with the thread locked)
*/
void
sched_thread_mode_undemote(thread_t thread, uint32_t reason)
{
assert(reason & TH_SFLAG_DEMOTED_MASK);
assert((thread->sched_flags & reason) == reason);
assert(thread->saved_mode != TH_MODE_NONE);
assert(thread->sched_mode == TH_MODE_TIMESHARE);
assert(thread->policy_reset == 0);
switch (reason) {
case TH_SFLAG_THROTTLED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_MODE_UNDEMOTE_THROTTLED),
thread_tid(thread), thread->sched_flags);
break;
case TH_SFLAG_FAILSAFE:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_MODE_UNDEMOTE_FAILSAFE),
thread_tid(thread), thread->sched_flags);
break;
case TH_SFLAG_RT_DISALLOWED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_MODE_UNDEMOTE_RT_DISALLOWED),
thread_tid(thread), thread->sched_flags);
break;
}
thread->sched_flags &= ~reason;
if (thread->sched_flags & TH_SFLAG_DEMOTED_MASK) {
/* Another demotion reason is still active */
return;
}
boolean_t removed = thread_run_queue_remove(thread);
sched_set_thread_mode(thread, thread->saved_mode);
thread->saved_mode = TH_MODE_NONE;
thread_recompute_priority(thread);
if (removed) {
thread_run_queue_reinsert(thread, SCHED_TAILQ);
}
}
/*
* Promote thread to have a sched pri floor for a specific reason
*
* Promotion must not last past syscall boundary
* Clients must always pair promote and demote 1:1,
* Handling nesting of the same promote reason is the client's responsibility
*
* Called at splsched with thread locked
*/
void
sched_thread_promote_reason(thread_t thread,
uint32_t reason,
__kdebug_only uintptr_t trace_obj /* already unslid */)
{
assert(reason & TH_SFLAG_PROMOTE_REASON_MASK);
assert((thread->sched_flags & reason) != reason);
switch (reason) {
case TH_SFLAG_RW_PROMOTED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_RW_PROMOTE),
thread_tid(thread), thread->sched_pri,
thread->base_pri, trace_obj);
break;
case TH_SFLAG_WAITQ_PROMOTED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAITQ_PROMOTE),
thread_tid(thread), thread->sched_pri,
thread->base_pri, trace_obj);
break;
case TH_SFLAG_EXEC_PROMOTED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_EXEC_PROMOTE),
thread_tid(thread), thread->sched_pri,
thread->base_pri, trace_obj);
break;
case TH_SFLAG_FLOOR_PROMOTED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_FLOOR_PROMOTE),
thread_tid(thread), thread->sched_pri,
thread->base_pri, trace_obj);
break;
}
thread->sched_flags |= reason;
thread_recompute_sched_pri(thread, SETPRI_DEFAULT);
}
/*
* End a specific promotion reason
* Demotes a thread back to its expected priority without the promotion in place
*
* Called at splsched with thread locked
*/
void
sched_thread_unpromote_reason(thread_t thread,
uint32_t reason,
__kdebug_only uintptr_t trace_obj /* already unslid */)
{
assert(reason & TH_SFLAG_PROMOTE_REASON_MASK);
assert((thread->sched_flags & reason) == reason);
switch (reason) {
case TH_SFLAG_RW_PROMOTED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_RW_DEMOTE),
thread_tid(thread), thread->sched_pri,
thread->base_pri, trace_obj);
break;
case TH_SFLAG_WAITQ_PROMOTED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_WAITQ_DEMOTE),
thread_tid(thread), thread->sched_pri,
thread->base_pri, trace_obj);
break;
case TH_SFLAG_EXEC_PROMOTED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_EXEC_DEMOTE),
thread_tid(thread), thread->sched_pri,
thread->base_pri, trace_obj);
break;
case TH_SFLAG_FLOOR_PROMOTED:
KDBG(MACHDBG_CODE(DBG_MACH_SCHED, MACH_FLOOR_DEMOTE),
thread_tid(thread), thread->sched_pri,
thread->base_pri, trace_obj);
break;
}
thread->sched_flags &= ~reason;
thread_recompute_sched_pri(thread, SETPRI_DEFAULT);
}