xnu-6153.11.26.tar.gz

[apple/xnu.git] / osfmk / kern / priority.c

diff --git a/osfmk/kern/priority.c b/osfmk/kern/priority.c
index dcf7715bd78b04f100a640852528e560509253cf..5ac1ce75682771a2cdec2bc0ae407397e584ead3 100644 (file)
--- a/osfmk/kern/priority.c
+++ b/osfmk/kern/priority.c
@@ -1,8 +1,8 @@
 /*
 /*

- * Copyright (c) 2000-2010 Apple Inc. All rights reserved.
+ * Copyright (c) 2000-2019 Apple Inc. All rights reserved.

  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  *
  * @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
  * 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


@@ -11,10 +11,10 @@
  * 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.
  * 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.
  * 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
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  * The Original Code and all software distributed under the License are
  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,


@@ -22,34 +22,34 @@
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.
  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  * Please see the License for the specific language governing rights and
  * limitations under the License.

- * 
+ *

  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 /*
  * @OSF_COPYRIGHT@
  */
  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  */
 /*
  * @OSF_COPYRIGHT@
  */

-/* 
+/*

  * Mach Operating System
  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  * All Rights Reserved.
  * 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.
  * 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 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
  * 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
  *  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.
  */
  * any improvements or extensions that they make and grant Carnegie Mellon
  * the rights to redistribute these changes.
  */


@@ -76,12 +76,16 @@
 #include <kern/ledger.h>
 #include <machine/machparam.h>
 #include <kern/machine.h>
 #include <kern/ledger.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
 
 
 #ifdef CONFIG_MACH_APPROXIMATE_TIME
 #include <machine/commpage.h>  /* for commpage_update_mach_approximate_time */
 #endif
 

-static void sched_update_thread_bucket(thread_t thread);
+#if MONOTONIC
+#include <kern/monotonic.h>
+#endif /* MONOTONIC */

 
 /*
  *     thread_quantum_expire:
 
 /*
  *     thread_quantum_expire:


@@ -93,15 +97,13 @@ static void sched_update_thread_bucket(thread_t thread);
 
 void
 thread_quantum_expire(
 
 void
 thread_quantum_expire(

-       timer_call_param_t      p0,
-       timer_call_param_t      p1)
+       timer_call_param_t      p0,
+       timer_call_param_t      p1)

 {
 {

-       processor_t                     processor = p0;
-       thread_t                        thread = p1;
-       ast_t                           preempt;
-       uint64_t                        ctime;
-       int                                     urgency;
-       uint64_t                        ignore1, ignore2;
+       processor_t                     processor = p0;
+       thread_t                        thread = p1;
+       ast_t                           preempt;
+       uint64_t                        ctime;

 
        assert(processor == current_processor());
        assert(thread == current_thread());
 
        assert(processor == current_processor());
        assert(thread == current_thread());


@@ -113,22 +115,22 @@ thread_quantum_expire(
        /*
         * We bill CPU time to both the individual thread and its task.
         *
        /*
         * 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.
+        * 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 thread_timer_event operation here.
+        * 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);
         */
        ledger_credit(thread->t_ledger, task_ledgers.cpu_time, thread->quantum_remaining);
        ledger_credit(thread->t_threadledger, thread_ledgers.cpu_time, thread->quantum_remaining);

-#ifdef CONFIG_BANK

        if (thread->t_bankledger) {
                ledger_credit(thread->t_bankledger, bank_ledgers.cpu_time,
        if (thread->t_bankledger) {
                ledger_credit(thread->t_bankledger, bank_ledgers.cpu_time,

-                               (thread->quantum_remaining - thread->t_deduct_bank_ledger_time));
+                   (thread->quantum_remaining - thread->t_deduct_bank_ledger_time));

        }
        thread->t_deduct_bank_ledger_time = 0;
        }
        thread->t_deduct_bank_ledger_time = 0;

-#endif

 
        ctime = mach_absolute_time();
 
 
        ctime = mach_absolute_time();
 


@@ -136,6 +138,10 @@ thread_quantum_expire(
        commpage_update_mach_approximate_time(ctime);
 #endif
 
        commpage_update_mach_approximate_time(ctime);
 #endif
 

+#if MONOTONIC
+       mt_sched_update(thread);
+#endif /* MONOTONIC */
+

        thread_lock(thread);
 
        /*
        thread_lock(thread);
 
        /*


@@ -148,16 +154,18 @@ thread_quantum_expire(
        /*
         *      Check for fail-safe trip.
         */
        /*
         *      Check for fail-safe trip.
         */

-       if ((thread->sched_mode == TH_MODE_REALTIME || thread->sched_mode == TH_MODE_FIXED) && 
-           !(thread->sched_flags & TH_SFLAG_PROMOTED_MASK) &&
-           !(thread->options & TH_OPT_SYSTEM_CRITICAL)) {
-               uint64_t new_computation;
-  
-               new_computation = ctime - thread->computation_epoch;
-               new_computation += thread->computation_metered;
-               if (new_computation > max_unsafe_computation) {
-                       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);
+       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;
+               if (new_computation > max_unsafe_computation) {
+                       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);

 
                        thread->safe_release = ctime + sched_safe_duration;
 
 
                        thread->safe_release = ctime + sched_safe_duration;
 


@@ -168,20 +176,15 @@ thread_quantum_expire(
        /*
         *      Recompute scheduled priority if appropriate.
         */
        /*
         *      Recompute scheduled priority if appropriate.
         */

-       if (SCHED(can_update_priority)(thread))
+       if (SCHED(can_update_priority)(thread)) {

                SCHED(update_priority)(thread);
                SCHED(update_priority)(thread);

-       else
+       } else {

                SCHED(lightweight_update_priority)(thread);
                SCHED(lightweight_update_priority)(thread);

+       }

 
 

-       if (thread->sched_mode != TH_MODE_REALTIME)
+       if (thread->sched_mode != TH_MODE_REALTIME) {

                SCHED(quantum_expire)(thread);
                SCHED(quantum_expire)(thread);

-
-       processor->current_pri = thread->sched_pri;
-       processor->current_thmode = thread->sched_mode;
-
-       /* Tell platform layer that we are still running this thread */
-       urgency = thread_get_urgency(thread, &ignore1, &ignore2);
-       machine_thread_going_on_core(thread, urgency, 0, 0);
+       }

 
        /*
         *      This quantum is up, give this thread another.
 
        /*
         *      This quantum is up, give this thread another.


@@ -198,31 +201,57 @@ thread_quantum_expire(
         * during privilege transitions, synthesize an event now.
         */
        if (!thread->precise_user_kernel_time) {
         * during privilege transitions, synthesize an event now.
         */
        if (!thread->precise_user_kernel_time) {

-               timer_switch(PROCESSOR_DATA(processor, current_state),
-                                        ctime,
-                                        PROCESSOR_DATA(processor, current_state));
-               timer_switch(PROCESSOR_DATA(processor, thread_timer),
-                                        ctime,
-                                        PROCESSOR_DATA(processor, thread_timer));
+               timer_update(PROCESSOR_DATA(processor, current_state), ctime);
+               timer_update(PROCESSOR_DATA(processor, thread_timer), ctime);
+               timer_update(&thread->runnable_timer, ctime);

        }
 
        }
 

+

        processor->quantum_end = ctime + thread->quantum_remaining;
 
        /*
        processor->quantum_end = ctime + thread->quantum_remaining;
 
        /*

-        *      Context switch check.
+        * 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.

         */
         */

-       if ((preempt = csw_check(processor, AST_QUANTUM)) != AST_NONE)
+
+       ast_t check_reason = AST_QUANTUM;
+       if (thread->task == kernel_task) {
+               check_reason |= AST_URGENT;
+       }
+
+       if ((preempt = csw_check(thread, processor, check_reason)) != AST_NONE) {

                ast_on(preempt);
                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);
 
 
        thread_unlock(thread);
 

-       timer_call_enter1(&processor->quantum_timer, thread,
-           processor->quantum_end, TIMER_CALL_SYS_CRITICAL | TIMER_CALL_LOCAL);
+       timer_call_quantum_timer_enter(&processor->quantum_timer, 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);
 #endif /* CONFIG_SCHED_TIMESHARE_CORE */
 
 
 #if defined(CONFIG_SCHED_TIMESHARE_CORE)
        sched_timeshare_consider_maintenance(ctime);
 #endif /* CONFIG_SCHED_TIMESHARE_CORE */
 

+#if __arm__ || __arm64__
+       if (thread->sched_mode == TH_MODE_REALTIME) {
+               sched_consider_recommended_cores(ctime, thread);
+       }
+#endif /* __arm__ || __arm64__ */

 
        KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_QUANTUM_EXPIRED) | DBG_FUNC_END, preempt, 0, 0, 0, 0);
 }
 
        KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_QUANTUM_EXPIRED) | DBG_FUNC_END, preempt, 0, 0, 0, 0);
 }


@@ -241,17 +270,83 @@ void
 sched_set_thread_base_priority(thread_t thread, int priority)
 {
        assert(priority >= MINPRI);
 sched_set_thread_base_priority(thread_t thread, int priority)
 {
        assert(priority >= MINPRI);

+       uint64_t ctime = 0;

 
 

-       if (thread->sched_mode == TH_MODE_REALTIME)
+       if (thread->sched_mode == TH_MODE_REALTIME) {

                assert(priority <= BASEPRI_RTQUEUES);
                assert(priority <= BASEPRI_RTQUEUES);

-       else
+       } else {

                assert(priority < BASEPRI_RTQUEUES);
                assert(priority < BASEPRI_RTQUEUES);

+       }

 
 

+       int old_base_pri = thread->base_pri;
+       thread->req_base_pri = priority;
+       if (thread->sched_flags & TH_SFLAG_BASE_PRI_FROZEN) {
+               priority = MAX(priority, old_base_pri);
+       }

        thread->base_pri = priority;
 
        thread->base_pri = priority;
 

-       sched_update_thread_bucket(thread);
+       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);

 
 

-       thread_recompute_sched_pri(thread, FALSE);
+       if (new_priority > thread->max_priority) {
+               new_priority = thread->max_priority;
+       }
+#if CONFIG_EMBEDDED
+       if (new_priority < MAXPRI_THROTTLE) {
+               new_priority = MAXPRI_THROTTLE;
+       }
+#endif /* CONFIG_EMBEDDED */
+
+       thread->importance = new_priority - thread->task_priority;
+
+       sched_set_thread_base_priority(thread, new_priority);
+
+       thread_unlock(thread);
+       splx(s);

 }
 
 /*
 }
 
 /*


@@ -261,37 +356,76 @@ sched_set_thread_base_priority(thread_t thread, int priority)
  *     according to its base priority if the
  *     thread has not been promoted or depressed.
  *
  *     according to its base priority if the
  *     thread has not been promoted or depressed.
  *

- *     This is the standard way to push base_pri changes into sched_pri,
- *     or to recalculate the appropriate sched_pri after clearing
+ *     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.
  *     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
  */
 void

-thread_recompute_sched_pri(
-                           thread_t thread,
-                           boolean_t override_depress)
+thread_recompute_sched_pri(thread_t thread, set_sched_pri_options_t options)

 {
 {

-       int priority;
+       uint32_t     sched_flags = thread->sched_flags;
+       sched_mode_t sched_mode  = thread->sched_mode;
+
+       int priority = thread->base_pri;

 
 

-       if (thread->sched_mode == TH_MODE_TIMESHARE)
+       if (sched_mode == TH_MODE_TIMESHARE) {

                priority = SCHED(compute_timeshare_priority)(thread);
                priority = SCHED(compute_timeshare_priority)(thread);

-       else
-               priority = thread->base_pri;
+       }
+
+       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 ((!(thread->sched_flags & TH_SFLAG_PROMOTED_MASK)  || (priority > thread->sched_pri)) &&
-           (!(thread->sched_flags & TH_SFLAG_DEPRESSED_MASK) || override_depress)) {
-               set_sched_pri(thread, 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);
+                       }
+               }

        }
        }

+
+       set_sched_pri(thread, priority, options);

 }
 
 void
 sched_default_quantum_expire(thread_t thread __unused)
 {
 }
 
 void
 sched_default_quantum_expire(thread_t thread __unused)
 {

-      /*
-       * No special behavior when a timeshare, fixed, or realtime thread
-       * uses up its entire quantum
-       */
+       /*
+        * No special behavior when a timeshare, fixed, or realtime thread
+        * uses up its entire quantum
+        */

 }
 
 #if defined(CONFIG_SCHED_TIMESHARE_CORE)
 }
 
 #if defined(CONFIG_SCHED_TIMESHARE_CORE)


@@ -323,29 +457,25 @@ lightweight_update_priority(thread_t thread)
                 *      during contention for processor
                 *      resources.
                 */
                 *      during contention for processor
                 *      resources.
                 */

-               if (thread->pri_shift < INT8_MAX)
+               if (thread->pri_shift < INT8_MAX) {

                        thread->sched_usage += delta;
                        thread->sched_usage += delta;

+               }

 
                thread->cpu_delta += delta;
 
 
                thread->cpu_delta += delta;
 

-               priority = sched_compute_timeshare_priority(thread);
-
+#if CONFIG_SCHED_CLUTCH

                /*
                /*

-                * Adjust the scheduled priority like thread_recompute_sched_pri,
-                * except with the benefit of knowing the thread is on this core.
+                * 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.

                 */
                 */

-               if ((!(thread->sched_flags & TH_SFLAG_PROMOTED_MASK)  || (priority > thread->sched_pri)) &&
-                   (!(thread->sched_flags & TH_SFLAG_DEPRESSED_MASK)) &&
-                   priority != thread->sched_pri) {
-
-                       thread->sched_pri = priority;
-
-                       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHANGE_PRIORITY),
-                                             (uintptr_t)thread_tid(thread),
-                                             thread->base_pri,
-                                             thread->sched_pri,
-                                             0, /* eventually, 'reason' */
-                                             0);
+               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);

                }
        }
 }
                }
        }
 }


@@ -357,17 +487,40 @@ lightweight_update_priority(thread_t thread)
  *     is  usage = (usage >> shift1) +/- (usage >> abs(shift2))  where the
  *     +/- is determined by the sign of shift 2.
  */
  *     is  usage = (usage >> shift1) +/- (usage >> abs(shift2))  where the
  *     +/- is determined by the sign of shift 2.
  */

-struct shift_data {
-       int     shift1;
-       int     shift2;
-};

 
 

-#define SCHED_DECAY_TICKS      32
-static struct shift_data       sched_decay_shifts[SCHED_DECAY_TICKS] = {
-       {1,1},{1,3},{1,-3},{2,-7},{3,5},{3,-5},{4,-8},{5,7},
-       {5,-7},{6,-10},{7,10},{7,-9},{8,-11},{9,12},{9,-11},{10,-13},
-       {11,14},{11,-13},{12,-15},{13,17},{13,-15},{14,-17},{15,19},{16,18},
-       {16,-19},{17,22},{18,20},{18,-20},{19,26},{20,22},{20,-22},{21,-27}
+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 }

 };
 
 /*
 };
 
 /*


@@ -378,20 +531,57 @@ static struct shift_data  sched_decay_shifts[SCHED_DECAY_TICKS] = {
 extern int sched_pri_decay_band_limit;
 
 
 extern int sched_pri_decay_band_limit;
 
 

+/* Only use the decay floor logic on embedded non-clutch schedulers */
+#if CONFIG_EMBEDDED && !CONFIG_SCHED_CLUTCH
+
+int
+sched_compute_timeshare_priority(thread_t thread)
+{
+       int decay_amount = (thread->sched_usage >> thread->pri_shift);
+       int decay_limit = sched_pri_decay_band_limit;
+
+       if (thread->base_pri > BASEPRI_FOREGROUND) {
+               decay_limit += (thread->base_pri - BASEPRI_FOREGROUND);
+       }
+
+       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 (thread->task->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 /* CONFIG_EMBEDDED && !CONFIG_SCHED_CLUTCH */
+

 int
 sched_compute_timeshare_priority(thread_t thread)
 {
        /* start with base priority */
        int priority = thread->base_pri - (thread->sched_usage >> thread->pri_shift);
 
 int
 sched_compute_timeshare_priority(thread_t thread)
 {
        /* start with base priority */
        int priority = thread->base_pri - (thread->sched_usage >> thread->pri_shift);
 

-       if (priority < MINPRI_USER)
+       if (priority < MINPRI_USER) {

                priority = MINPRI_USER;
                priority = MINPRI_USER;

-       else if (priority > MAXPRI_KERNEL)
+       } else if (priority > MAXPRI_KERNEL) {

                priority = MAXPRI_KERNEL;
                priority = MAXPRI_KERNEL;

+       }

 
        return priority;
 }
 
 
        return priority;
 }
 

+#endif /* CONFIG_EMBEDDED && !CONFIG_SCHED_CLUTCH */

 
 /*
  *     can_update_priority
 
 /*
  *     can_update_priority


@@ -402,12 +592,13 @@ sched_compute_timeshare_priority(thread_t thread)
  */
 boolean_t
 can_update_priority(
  */
 boolean_t
 can_update_priority(

-                                       thread_t        thread)
+       thread_t        thread)

 {
 {

-       if (sched_tick == thread->sched_stamp)
-               return (FALSE);
-       else
-               return (TRUE);
+       if (sched_tick == thread->sched_stamp) {
+               return FALSE;
+       } else {
+               return TRUE;
+       }

 }
 
 /*
 }
 
 /*


@@ -419,7 +610,7 @@ can_update_priority(
  */
 void
 update_priority(
  */
 void
 update_priority(

-       thread_t        thread)
+       thread_t        thread)

 {
        uint32_t ticks, delta;
 
 {
        uint32_t ticks, delta;
 


@@ -428,11 +619,10 @@ update_priority(
 
        thread->sched_stamp += ticks;
 
 
        thread->sched_stamp += ticks;
 

-       thread->pri_shift = sched_pri_shifts[thread->th_sched_bucket];
-

        /* If requested, accelerate aging of sched_usage */
        /* If requested, accelerate aging of sched_usage */

-       if (sched_decay_usage_age_factor > 1)
+       if (sched_decay_usage_age_factor > 1) {

                ticks *= sched_decay_usage_age_factor;
                ticks *= sched_decay_usage_age_factor;

+       }

 
        /*
         *      Gather cpu usage data.
 
        /*
         *      Gather cpu usage data.


@@ -440,28 +630,38 @@ update_priority(
        thread_timer_delta(thread, delta);
        if (ticks < SCHED_DECAY_TICKS) {
                /*
        thread_timer_delta(thread, delta);
        if (ticks < SCHED_DECAY_TICKS) {
                /*

-                *      Accumulate timesharing usage only
-                *      during contention for processor
-                *      resources.
+                *      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->pri_shift < INT8_MAX) {

                        thread->sched_usage += delta;
                        thread->sched_usage += delta;

+               }

 
                thread->cpu_usage += delta + thread->cpu_delta;
                thread->cpu_delta = 0;
 
 
                thread->cpu_usage += delta + thread->cpu_delta;
                thread->cpu_delta = 0;
 

-               struct shift_data *shiftp = &sched_decay_shifts[ticks];
+#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) +
 
                if (shiftp->shift2 > 0) {
                        thread->cpu_usage =   (thread->cpu_usage >> shiftp->shift1) +

-                                             (thread->cpu_usage >> shiftp->shift2);
+                           (thread->cpu_usage >> shiftp->shift2);

                        thread->sched_usage = (thread->sched_usage >> shiftp->shift1) +
                        thread->sched_usage = (thread->sched_usage >> shiftp->shift1) +

-                                             (thread->sched_usage >> shiftp->shift2);
+                           (thread->sched_usage >> shiftp->shift2);

                } else {
                        thread->cpu_usage =   (thread->cpu_usage >>   shiftp->shift1) -
                } else {
                        thread->cpu_usage =   (thread->cpu_usage >>   shiftp->shift1) -

-                                             (thread->cpu_usage >> -(shiftp->shift2));
+                           (thread->cpu_usage >> -(shiftp->shift2));

                        thread->sched_usage = (thread->sched_usage >>   shiftp->shift1) -
                        thread->sched_usage = (thread->sched_usage >>   shiftp->shift1) -

-                                             (thread->sched_usage >> -(shiftp->shift2));
+                           (thread->sched_usage >> -(shiftp->shift2));

                }
        } else {
                thread->cpu_usage = thread->cpu_delta = 0;
                }
        } else {
                thread->cpu_usage = thread->cpu_delta = 0;


@@ -477,36 +677,22 @@ update_priority(
        }
 
        /*
        }
 
        /*

-        *      Recompute scheduled priority if appropriate.
+        * 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 (thread->sched_mode == TH_MODE_TIMESHARE) {
-               int priority = sched_compute_timeshare_priority(thread);
-
-               /*
-                * Adjust the scheduled priority like thread_recompute_sched_pri,
-                * except without setting an AST.
-                */
-               if ((!(thread->sched_flags & TH_SFLAG_PROMOTED_MASK)  || (priority > thread->sched_pri)) &&
-                   (!(thread->sched_flags & TH_SFLAG_DEPRESSED_MASK)) &&
-                   priority != thread->sched_pri) {
-
-                       boolean_t removed = thread_run_queue_remove(thread);
-
-                       thread->sched_pri = priority;
-
-                       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_CHANGE_PRIORITY),
-                                             (uintptr_t)thread_tid(thread),
-                                             thread->base_pri,
-                                             thread->sched_pri,
-                                             0, /* eventually, 'reason' */
-                                             0);
+#if 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 */

 
 

-                       if (removed)
-                               thread_run_queue_reinsert(thread, SCHED_TAILQ);
-               }
+       /* Recompute scheduled priority if appropriate. */
+       if (thread->sched_mode == TH_MODE_TIMESHARE) {
+               thread_recompute_sched_pri(thread, SETPRI_LAZY);

        }
        }

-
-       return;

 }
 
 #endif /* CONFIG_SCHED_TIMESHARE_CORE */
 }
 
 #endif /* CONFIG_SCHED_TIMESHARE_CORE */


@@ -515,38 +701,40 @@ update_priority(
 /*
  * TH_BUCKET_RUN is a count of *all* runnable non-idle threads.
  * Each other bucket is a count of the runnable non-idle threads
 /*
  * 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.
+ * 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.

  */
  */

-volatile uint32_t       sched_run_buckets[TH_BUCKET_MAX];
+uint32_t       sched_run_buckets[TH_BUCKET_MAX];

 
 static void
 sched_incr_bucket(sched_bucket_t bucket)
 {
        assert(bucket >= TH_BUCKET_FIXPRI &&
 
 static void
 sched_incr_bucket(sched_bucket_t bucket)
 {
        assert(bucket >= TH_BUCKET_FIXPRI &&

-              bucket <= TH_BUCKET_SHARE_BG);
+           bucket <= TH_BUCKET_SHARE_BG);

 
 

-       hw_atomic_add(&sched_run_buckets[bucket], 1);
+       os_atomic_inc(&sched_run_buckets[bucket], relaxed);

 }
 
 static void
 sched_decr_bucket(sched_bucket_t bucket)
 {
        assert(bucket >= TH_BUCKET_FIXPRI &&
 }
 
 static void
 sched_decr_bucket(sched_bucket_t bucket)
 {
        assert(bucket >= TH_BUCKET_FIXPRI &&

-              bucket <= TH_BUCKET_SHARE_BG);
+           bucket <= TH_BUCKET_SHARE_BG);

 
 

-       assert(sched_run_buckets[bucket] > 0);
+       assert(os_atomic_load(&sched_run_buckets[bucket], relaxed) > 0);

 
 

-       hw_atomic_sub(&sched_run_buckets[bucket], 1);
+       os_atomic_dec(&sched_run_buckets[bucket], relaxed);

 }
 
 }
 

-/* TH_RUN & !TH_IDLE controls whether a thread has a run count */
-

 uint32_t
 sched_run_incr(thread_t thread)
 {
 uint32_t
 sched_run_incr(thread_t thread)
 {

-       assert((thread->state & (TH_RUN|TH_IDLE)) == TH_RUN);
+       assert((thread->state & (TH_RUN | TH_IDLE)) == TH_RUN);

 
 

-       uint32_t new_count = hw_atomic_add(&sched_run_buckets[TH_BUCKET_RUN], 1);
+       uint32_t new_count = os_atomic_inc(&sched_run_buckets[TH_BUCKET_RUN], relaxed);

 
        sched_incr_bucket(thread->th_sched_bucket);
 
 
        sched_incr_bucket(thread->th_sched_bucket);
 


@@ -556,16 +744,16 @@ sched_run_incr(thread_t thread)
 uint32_t
 sched_run_decr(thread_t thread)
 {
 uint32_t
 sched_run_decr(thread_t thread)
 {

-       assert((thread->state & (TH_RUN|TH_IDLE)) != TH_RUN);
+       assert((thread->state & (TH_RUN | TH_IDLE)) != TH_RUN);

 
        sched_decr_bucket(thread->th_sched_bucket);
 
 
        sched_decr_bucket(thread->th_sched_bucket);
 

-       uint32_t new_count = hw_atomic_sub(&sched_run_buckets[TH_BUCKET_RUN], 1);
+       uint32_t new_count = os_atomic_dec(&sched_run_buckets[TH_BUCKET_RUN], relaxed);

 
        return new_count;
 }
 
 
        return new_count;
 }
 

-static void
+void

 sched_update_thread_bucket(thread_t thread)
 {
        sched_bucket_t old_bucket = thread->th_sched_bucket;
 sched_update_thread_bucket(thread_t thread)
 {
        sched_bucket_t old_bucket = thread->th_sched_bucket;


@@ -578,12 +766,15 @@ sched_update_thread_bucket(thread_t thread)
                break;
 
        case TH_MODE_TIMESHARE:
                break;
 
        case TH_MODE_TIMESHARE:

-               if (thread->base_pri > BASEPRI_UTILITY)
+               if (thread->base_pri > BASEPRI_DEFAULT) {

                        new_bucket = TH_BUCKET_SHARE_FG;
                        new_bucket = TH_BUCKET_SHARE_FG;

-               else if (thread->base_pri > MAXPRI_THROTTLE)
+               } 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;
                        new_bucket = TH_BUCKET_SHARE_UT;

-               else
+               } else {

                        new_bucket = TH_BUCKET_SHARE_BG;
                        new_bucket = TH_BUCKET_SHARE_BG;

+               }

                break;
 
        default:
                break;
 
        default:


@@ -595,7 +786,7 @@ sched_update_thread_bucket(thread_t thread)
                thread->th_sched_bucket = new_bucket;
                thread->pri_shift = sched_pri_shifts[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) {
+               if ((thread->state & (TH_RUN | TH_IDLE)) == TH_RUN) {

                        sched_decr_bucket(old_bucket);
                        sched_incr_bucket(new_bucket);
                }
                        sched_decr_bucket(old_bucket);
                        sched_incr_bucket(new_bucket);
                }


@@ -627,7 +818,7 @@ sched_set_thread_mode(thread_t thread, sched_mode_t new_mode)
 
        thread->sched_mode = new_mode;
 
 
        thread->sched_mode = new_mode;
 

-       sched_update_thread_bucket(thread);
+       SCHED(update_thread_bucket)(thread);

 }
 
 /*
 }
 
 /*


@@ -639,8 +830,9 @@ sched_thread_mode_demote(thread_t thread, uint32_t reason)
        assert(reason & TH_SFLAG_DEMOTED_MASK);
        assert((thread->sched_flags & reason) != reason);
 
        assert(reason & TH_SFLAG_DEMOTED_MASK);
        assert((thread->sched_flags & reason) != reason);
 

-       if (thread->policy_reset)
+       if (thread->policy_reset) {

                return;
                return;

+       }

 
        if (thread->sched_flags & TH_SFLAG_DEMOTED_MASK) {
                /* Another demotion reason is already active */
 
        if (thread->sched_flags & TH_SFLAG_DEMOTED_MASK) {
                /* Another demotion reason is already active */


@@ -660,8 +852,9 @@ sched_thread_mode_demote(thread_t thread, uint32_t reason)
 
        thread_recompute_priority(thread);
 
 
        thread_recompute_priority(thread);
 

-       if (removed)
+       if (removed) {

                thread_run_queue_reinsert(thread, SCHED_TAILQ);
                thread_run_queue_reinsert(thread, SCHED_TAILQ);

+       }

 }
 
 /*
 }
 
 /*


@@ -691,8 +884,84 @@ sched_thread_mode_undemote(thread_t thread, uint32_t reason)
 
        thread_recompute_priority(thread);
 
 
        thread_recompute_priority(thread);
 

-       if (removed)
+       if (removed) {

                thread_run_queue_reinsert(thread, SCHED_TAILQ);
                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;
+       }
+
+       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;
+       }

 
 

+       thread->sched_flags &= ~reason;
+
+       thread_recompute_sched_pri(thread, SETPRI_DEFAULT);
+}