]> git.saurik.com Git - apple/xnu.git/blobdiff - osfmk/kern/priority.c
xnu-3789.21.4.tar.gz
[apple/xnu.git] / osfmk / kern / priority.c
index 0b64ac8aa13de300d24cc8ae9f2f225732f21516..f4f5b1cc8a1a6e9b3159f8e372816575d9e43985 100644 (file)
 #include <kern/processor.h>
 #include <kern/ledger.h>
 #include <machine/machparam.h>
+#include <kern/machine.h>
 
 #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);
+
 /*
  *     thread_quantum_expire:
  *
@@ -97,8 +100,13 @@ thread_quantum_expire(
        thread_t                        thread = p1;
        ast_t                           preempt;
        uint64_t                        ctime;
+       int                                     urgency;
+       uint64_t                        ignore1, ignore2;
 
        assert(processor == current_processor());
+       assert(thread == current_thread());
+
+       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_QUANTUM_EXPIRED) | DBG_FUNC_START, 0, 0, 0, 0, 0);
 
        SCHED_STATS_QUANTUM_TIMER_EXPIRATION(processor);
 
@@ -108,6 +116,9 @@ thread_quantum_expire(
         * 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.
         */
        ledger_credit(thread->t_ledger, task_ledgers.cpu_time, thread->quantum_remaining);
        ledger_credit(thread->t_threadledger, thread_ledgers.cpu_time, thread->quantum_remaining);
@@ -121,17 +132,19 @@ thread_quantum_expire(
 
        ctime = mach_absolute_time();
 
+#ifdef CONFIG_MACH_APPROXIMATE_TIME
+       commpage_update_mach_approximate_time(ctime);
+#endif
+
        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;
 
-#ifdef CONFIG_MACH_APPROXIMATE_TIME
-       commpage_update_mach_approximate_time(ctime);
-#endif
        /*
         *      Check for fail-safe trip.
         */
@@ -160,16 +173,20 @@ thread_quantum_expire(
        else
                SCHED(lightweight_update_priority)(thread);
 
-       SCHED(quantum_expire)(thread);
-       
+       if (thread->sched_mode != TH_MODE_REALTIME)
+               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);
+
        /*
         *      This quantum is up, give this thread another.
         */
-       if (first_timeslice(processor))
-               processor->timeslice--;
+       processor->first_timeslice = FALSE;
 
        thread_quantum_init(thread);
 
@@ -190,8 +207,6 @@ thread_quantum_expire(
        }
 
        processor->quantum_end = ctime + thread->quantum_remaining;
-       timer_call_enter1(&processor->quantum_timer, thread,
-           processor->quantum_end, TIMER_CALL_SYS_CRITICAL | TIMER_CALL_LOCAL);
 
        /*
         *      Context switch check.
@@ -201,9 +216,15 @@ thread_quantum_expire(
 
        thread_unlock(thread);
 
+       timer_call_enter1(&processor->quantum_timer, thread,
+           processor->quantum_end, TIMER_CALL_SYS_CRITICAL | TIMER_CALL_LOCAL);
+
 #if defined(CONFIG_SCHED_TIMESHARE_CORE)
-       sched_traditional_consider_maintenance(ctime);
-#endif /* CONFIG_SCHED_TIMESHARE_CORE */       
+       sched_timeshare_consider_maintenance(ctime);
+#endif /* CONFIG_SCHED_TIMESHARE_CORE */
+
+
+       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_QUANTUM_EXPIRED) | DBG_FUNC_END, preempt, 0, 0, 0, 0);
 }
 
 /*
@@ -212,35 +233,91 @@ thread_quantum_expire(
  *     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)
 {
-       thread->priority = priority;
-       SCHED(compute_priority)(thread, FALSE);
+       assert(priority >= MINPRI);
+
+       if (thread->sched_mode == TH_MODE_REALTIME)
+               assert(priority <= BASEPRI_RTQUEUES);
+       else
+               assert(priority < BASEPRI_RTQUEUES);
+
+       thread->base_pri = priority;
+
+       sched_update_thread_bucket(thread);
+
+       thread_recompute_sched_pri(thread, FALSE);
 }
 
+/*
+ *     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 standard way to push base_pri changes into sched_pri,
+ *     or to recalculate the appropriate sched_pri after clearing
+ *     a promotion or depression.
+ *
+ *     Called at splsched with the thread locked.
+ */
+void
+thread_recompute_sched_pri(
+                           thread_t thread,
+                           boolean_t override_depress)
+{
+       int priority;
+
+       if (thread->sched_mode == TH_MODE_TIMESHARE)
+               priority = SCHED(compute_timeshare_priority)(thread);
+       else
+               priority = thread->base_pri;
 
-#if defined(CONFIG_SCHED_TIMESHARE_CORE)
+       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);
+       }
+}
 
 void
-sched_traditional_quantum_expire(thread_t      thread __unused)
+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)
+
+/*
+ *     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)
 {
+       assert(thread->runq == PROCESSOR_NULL);
+       assert(thread == current_thread());
+
        if (thread->sched_mode == TH_MODE_TIMESHARE) {
-               register uint32_t       delta;
-               
+               int priority;
+               uint32_t delta;
+
                thread_timer_delta(thread, delta);
-               
+
                /*
                 *      Accumulate timesharing usage only
                 *      during contention for processor
@@ -248,18 +325,29 @@ lightweight_update_priority(thread_t thread)
                 */
                if (thread->pri_shift < INT8_MAX)
                        thread->sched_usage += delta;
-               
+
                thread->cpu_delta += delta;
-               
+
+               priority = sched_compute_timeshare_priority(thread);
+
                /*
-                * Adjust the scheduled priority if
-                * the thread has not been promoted
-                * and is not depressed.
+                * Adjust the scheduled priority like thread_recompute_sched_pri,
+                * except with the benefit of knowing the thread is on this core.
                 */
-               if (    !(thread->sched_flags & TH_SFLAG_PROMOTED_MASK) &&
-                       !(thread->sched_flags & TH_SFLAG_DEPRESSED_MASK)                )
-                       compute_my_priority(thread);
-       }       
+               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);
+               }
+       }
 }
 
 /*
@@ -283,83 +371,27 @@ static struct shift_data  sched_decay_shifts[SCHED_DECAY_TICKS] = {
 };
 
 /*
- *     do_priority_computation:
+ *     sched_compute_timeshare_priority:
  *
  *     Calculate the timesharing priority based upon usage and load.
  */
 extern int sched_pri_decay_band_limit;
 
 
-static int do_priority_computation(thread_t th) {                                                                                                                      
-       register int priority = th->priority            /* start with base priority */          
-           - (th->sched_usage >> th->pri_shift);                               
-       if (priority < MINPRI_USER)                                                                                     
-               priority = MINPRI_USER;                                                                                 
-       else                                                                                                                            
-       if (priority > MAXPRI_KERNEL)                                                                                   
-               priority = MAXPRI_KERNEL;       
-
-       return priority;                                                                                
-}
-
-
-/*
- *     compute_priority:
- *
- *     Reset the scheduled priority of the thread
- *     according to its base priority if the
- *     thread has not been promoted or depressed.
- *
- *     Called with the thread locked.
- */
-void
-compute_priority(
-       register thread_t       thread,
-       boolean_t                       override_depress)
+int
+sched_compute_timeshare_priority(thread_t thread)
 {
-       register int            priority;
+       /* start with base priority */
+       int priority = thread->base_pri - (thread->sched_usage >> thread->pri_shift);
 
-       if (thread->sched_mode == TH_MODE_TIMESHARE)
-               priority = do_priority_computation(thread);
-       else
-               priority = thread->priority;
+       if (priority < MINPRI_USER)
+               priority = MINPRI_USER;
+       else if (priority > MAXPRI_KERNEL)
+               priority = MAXPRI_KERNEL;
 
-       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);
-       }
+       return priority;
 }
 
-/*
- *     compute_my_priority:
- *
- *     Reset the scheduled priority for
- *     a timesharing thread.
- *
- *     Only for use on the current thread
- *     if timesharing and not depressed.
- *
- *     Called with the thread locked.
- */
-void
-compute_my_priority(
-       register thread_t       thread)
-{
-       register int            priority;
-
-       priority = do_priority_computation(thread);
-       assert(thread->runq == PROCESSOR_NULL);
-
-       if (priority != thread->sched_pri) {
-               KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_DECAY_PRIORITY)|DBG_FUNC_NONE,
-                            (uintptr_t)thread_tid(thread),
-                            thread->priority,
-                            thread->sched_pri,
-                            priority,
-                            0);
-       }
-       thread->sched_pri = priority;
-}
 
 /*
  *     can_update_priority
@@ -387,20 +419,16 @@ can_update_priority(
  */
 void
 update_priority(
-       register thread_t       thread)
+       thread_t        thread)
 {
-       register unsigned       ticks;
-       register uint32_t       delta;
+       uint32_t ticks, delta;
 
        ticks = sched_tick - thread->sched_stamp;
        assert(ticks != 0);
+
        thread->sched_stamp += ticks;
-       if (sched_use_combined_fgbg_decay)
-               thread->pri_shift = sched_combined_fgbg_pri_shift;
-       else if (thread->sched_flags & TH_SFLAG_THROTTLED)
-               thread->pri_shift = sched_background_pri_shift;
-       else
-               thread->pri_shift = sched_pri_shift;
+
+       thread->pri_shift = sched_pri_shifts[thread->th_sched_bucket];
 
        /* If requested, accelerate aging of sched_usage */
        if (sched_decay_usage_age_factor > 1)
@@ -411,8 +439,6 @@ update_priority(
         */
        thread_timer_delta(thread, delta);
        if (ticks < SCHED_DECAY_TICKS) {
-               register struct shift_data      *shiftp;
-
                /*
                 *      Accumulate timesharing usage only
                 *      during contention for processor
@@ -424,25 +450,20 @@ update_priority(
                thread->cpu_usage += delta + thread->cpu_delta;
                thread->cpu_delta = 0;
 
-               shiftp = &sched_decay_shifts[ticks];
+               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));
+                       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 {
+       } else {
                thread->cpu_usage = thread->cpu_delta = 0;
                thread->sched_usage = 0;
        }
@@ -455,127 +476,131 @@ update_priority(
                sched_thread_mode_undemote(thread, TH_SFLAG_FAILSAFE);
        }
 
-
        /*
         *      Recompute scheduled priority if appropriate.
         */
-       if (    (thread->sched_mode == TH_MODE_TIMESHARE)       &&
-                       !(thread->sched_flags & TH_SFLAG_PROMOTED_MASK) &&
-                       !(thread->sched_flags & TH_SFLAG_DEPRESSED_MASK)                ) {
-               register int            new_pri;
-
-               new_pri = do_priority_computation(thread);
-               if (new_pri != thread->sched_pri) {
-                       boolean_t               removed = thread_run_queue_remove(thread);
-
-#if 0
-                       if (sched_use_combined_fgbg_decay && ((thread)->task->max_priority > MAXPRI_THROTTLE) && (new_pri == MAXPRI_THROTTLE)) {
-                               /* with the alternate (new) algorithm, would we have decayed this far? */
-                               int alt_pri = thread->priority - (thread->sched_usage >> sched_pri_shift);
-                               if ((alt_pri > new_pri) && (sched_background_count > 0)) {
-                                       printf("thread %p would have decayed to only %d instead of %d\n", thread, alt_pri, new_pri);
-                               }
-                       }
-#endif
+       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) {
 
-                       KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_SCHED_DECAY_PRIORITY)|DBG_FUNC_NONE,
-                                                         (uintptr_t)thread_tid(thread),
-                                                         thread->priority,
-                                                         thread->sched_pri,
-                                                         new_pri,
-                                                         0);
-                       thread->sched_pri = new_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 (removed)
-                               thread_setrun(thread, SCHED_TAILQ);
+                               thread_run_queue_reinsert(thread, SCHED_TAILQ);
                }
        }
-       
+
        return;
 }
 
 #endif /* CONFIG_SCHED_TIMESHARE_CORE */
 
-#if MACH_ASSERT
-/* sched_mode == TH_MODE_TIMESHARE controls whether a thread has a timeshare count when it has a run count */
 
-void sched_share_incr(thread_t thread) {
-       assert((thread->state & (TH_RUN|TH_IDLE)) == TH_RUN);
-       assert(thread->sched_mode == TH_MODE_TIMESHARE);
-       assert(thread->SHARE_COUNT == 0);
-       thread->SHARE_COUNT++;
-       (void)hw_atomic_add(&sched_share_count, 1);
+/*
+ * 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.
+ */
+volatile 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);
+
+       hw_atomic_add(&sched_run_buckets[bucket], 1);
 }
 
-void sched_share_decr(thread_t thread) {
-       assert((thread->state & (TH_RUN|TH_IDLE)) != TH_RUN || thread->sched_mode != TH_MODE_TIMESHARE);
-       assert(thread->SHARE_COUNT == 1);
-       (void)hw_atomic_sub(&sched_share_count, 1);
-       thread->SHARE_COUNT--;
+static void
+sched_decr_bucket(sched_bucket_t bucket)
+{
+       assert(bucket >= TH_BUCKET_FIXPRI &&
+              bucket <= TH_BUCKET_SHARE_BG);
+
+       assert(sched_run_buckets[bucket] > 0);
+
+       hw_atomic_sub(&sched_run_buckets[bucket], 1);
 }
 
-/* TH_SFLAG_THROTTLED controls whether a thread has a background count when it has a run count and a share count */
+/* TH_RUN & !TH_IDLE controls whether a thread has a run count */
 
-void sched_background_incr(thread_t thread) {
+uint32_t
+sched_run_incr(thread_t thread)
+{
        assert((thread->state & (TH_RUN|TH_IDLE)) == TH_RUN);
-       assert(thread->sched_mode == TH_MODE_TIMESHARE);
-       assert((thread->sched_flags & TH_SFLAG_THROTTLED) == TH_SFLAG_THROTTLED);
 
-       assert(thread->BG_COUNT == 0);
-       thread->BG_COUNT++;
-       int val = hw_atomic_add(&sched_background_count, 1);
-       assert(val >= 0);
+       uint32_t new_count = hw_atomic_add(&sched_run_buckets[TH_BUCKET_RUN], 1);
 
-       /* Always do the background change while holding a share count */
-       assert(thread->SHARE_COUNT == 1);
-}
+       sched_incr_bucket(thread->th_sched_bucket);
 
-void sched_background_decr(thread_t thread) {
-       if ((thread->state & (TH_RUN|TH_IDLE)) == TH_RUN && thread->sched_mode == TH_MODE_TIMESHARE)
-               assert((thread->sched_flags & TH_SFLAG_THROTTLED) != TH_SFLAG_THROTTLED);
-       assert(thread->BG_COUNT == 1);
-       int val = hw_atomic_sub(&sched_background_count, 1);
-       thread->BG_COUNT--;
-       assert(val >= 0);
-       assert(thread->BG_COUNT == 0);
-
-       /* Always do the background change while holding a share count */
-       assert(thread->SHARE_COUNT == 1);
+       return new_count;
 }
 
+uint32_t
+sched_run_decr(thread_t thread)
+{
+       assert((thread->state & (TH_RUN|TH_IDLE)) != TH_RUN);
 
-void
-assert_thread_sched_count(thread_t thread) {
-       /* Only 0 or 1 are acceptable values */
-       assert(thread->BG_COUNT    == 0 || thread->BG_COUNT    == 1);
-       assert(thread->SHARE_COUNT == 0 || thread->SHARE_COUNT == 1);
-
-       /* BG is only allowed when you already have a share count */
-       if (thread->BG_COUNT == 1)
-               assert(thread->SHARE_COUNT == 1);
-       if (thread->SHARE_COUNT == 0)
-               assert(thread->BG_COUNT == 0);
-
-       if ((thread->state & (TH_RUN|TH_IDLE)) != TH_RUN ||
-           (thread->sched_mode != TH_MODE_TIMESHARE))
-               assert(thread->SHARE_COUNT == 0);
-
-       if ((thread->state & (TH_RUN|TH_IDLE)) == TH_RUN &&
-           (thread->sched_mode == TH_MODE_TIMESHARE))
-               assert(thread->SHARE_COUNT == 1);
-
-       if ((thread->state & (TH_RUN|TH_IDLE)) != TH_RUN ||
-           (thread->sched_mode != TH_MODE_TIMESHARE)    ||
-           !(thread->sched_flags & TH_SFLAG_THROTTLED))
-               assert(thread->BG_COUNT == 0);
-
-       if ((thread->state & (TH_RUN|TH_IDLE)) == TH_RUN &&
-           (thread->sched_mode == TH_MODE_TIMESHARE)    &&
-           (thread->sched_flags & TH_SFLAG_THROTTLED))
-               assert(thread->BG_COUNT == 1);
+       sched_decr_bucket(thread->th_sched_bucket);
+
+       uint32_t new_count = hw_atomic_sub(&sched_run_buckets[TH_BUCKET_RUN], 1);
+
+       return new_count;
 }
 
-#endif /* MACH_ASSERT */
+static 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_UTILITY)
+                       new_bucket = TH_BUCKET_SHARE_FG;
+               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);
+               }
+       }
+}
 
 /*
  * Set the thread's true scheduling mode
@@ -587,42 +612,22 @@ assert_thread_sched_count(thread_t thread) {
 void
 sched_set_thread_mode(thread_t thread, sched_mode_t new_mode)
 {
-       assert_thread_sched_count(thread);
-
-       sched_mode_t old_mode = thread->sched_mode;
-
-       thread->sched_mode = new_mode;
+       assert(thread->runq == PROCESSOR_NULL);
 
        switch (new_mode) {
-               case TH_MODE_FIXED:
-               case TH_MODE_REALTIME:
-                       if (old_mode == TH_MODE_TIMESHARE) {
-                               if ((thread->state & (TH_RUN|TH_IDLE)) == TH_RUN) {
-                                       if (thread->sched_flags & TH_SFLAG_THROTTLED)
-                                               sched_background_decr(thread);
-
-                                       sched_share_decr(thread);
-                               }
-                       }
-                       break;
-
-               case TH_MODE_TIMESHARE:
-                       if (old_mode != TH_MODE_TIMESHARE) {
-                               if ((thread->state & (TH_RUN|TH_IDLE)) == TH_RUN) {
-                                       sched_share_incr(thread);
-
-                                       if (thread->sched_flags & TH_SFLAG_THROTTLED)
-                                               sched_background_incr(thread);
-                               }
-                       }
-                       break;
-
-               default:
-                       panic("unexpected mode: %d", new_mode);
-                       break;
+       case TH_MODE_FIXED:
+       case TH_MODE_REALTIME:
+       case TH_MODE_TIMESHARE:
+               break;
+
+       default:
+               panic("unexpected mode: %d", new_mode);
+               break;
        }
 
-       assert_thread_sched_count(thread);
+       thread->sched_mode = new_mode;
+
+       sched_update_thread_bucket(thread);
 }
 
 /*
@@ -633,7 +638,6 @@ sched_thread_mode_demote(thread_t thread, uint32_t reason)
 {
        assert(reason & TH_SFLAG_DEMOTED_MASK);
        assert((thread->sched_flags & reason) != reason);
-       assert_thread_sched_count(thread);
 
        if (thread->policy_reset)
                return;
@@ -648,19 +652,16 @@ sched_thread_mode_demote(thread_t thread, uint32_t reason)
 
        boolean_t removed = thread_run_queue_remove(thread);
 
-       if (thread->sched_mode == TH_MODE_REALTIME)
-               thread->priority = DEPRESSPRI;
-
        thread->sched_flags |= reason;
 
        thread->saved_mode = thread->sched_mode;
 
        sched_set_thread_mode(thread, TH_MODE_TIMESHARE);
 
-       if (removed)
-               thread_setrun(thread, SCHED_TAILQ);
+       thread_recompute_priority(thread);
 
-       assert_thread_sched_count(thread);
+       if (removed)
+               thread_run_queue_reinsert(thread, SCHED_TAILQ);
 }
 
 /*
@@ -675,8 +676,6 @@ sched_thread_mode_undemote(thread_t thread, uint32_t reason)
        assert(thread->sched_mode == TH_MODE_TIMESHARE);
        assert(thread->policy_reset == 0);
 
-       assert_thread_sched_count(thread);
-
        thread->sched_flags &= ~reason;
 
        if (thread->sched_flags & TH_SFLAG_DEMOTED_MASK) {
@@ -690,58 +689,10 @@ sched_thread_mode_undemote(thread_t thread, uint32_t reason)
 
        thread->saved_mode = TH_MODE_NONE;
 
-       if (thread->sched_mode == TH_MODE_REALTIME) {
-               thread->priority = BASEPRI_RTQUEUES;
-       }
-
-       SCHED(compute_priority)(thread, FALSE);
+       thread_recompute_priority(thread);
 
        if (removed)
-               thread_setrun(thread, SCHED_TAILQ);
+               thread_run_queue_reinsert(thread, SCHED_TAILQ);
 }
 
-/*
- * Set the thread to be categorized as 'background'
- * Called with thread mutex and thread lock held
- *
- * TODO: Eventually, 'background' should be a true sched_mode.
- */
-void
-sched_set_thread_throttled(thread_t thread, boolean_t wants_throttle)
-{
-       if (thread->policy_reset)
-               return;
-
-       assert(((thread->sched_flags & TH_SFLAG_THROTTLED) ? TRUE : FALSE) != wants_throttle);
-
-       assert_thread_sched_count(thread);
-
-       /*
-        * When backgrounding a thread, iOS has the semantic that
-        * realtime and fixed priority threads should be demoted
-        * to timeshare background threads.
-        *
-        * On OSX, realtime and fixed priority threads don't lose their mode.
-        */
-
-       if (wants_throttle) {
-               thread->sched_flags |= TH_SFLAG_THROTTLED;
-               if ((thread->state & (TH_RUN|TH_IDLE)) == TH_RUN && thread->sched_mode == TH_MODE_TIMESHARE) {
-                       sched_background_incr(thread);
-               }
-
-               assert_thread_sched_count(thread);
-
-       } else {
-               thread->sched_flags &= ~TH_SFLAG_THROTTLED;
-               if ((thread->state & (TH_RUN|TH_IDLE)) == TH_RUN && thread->sched_mode == TH_MODE_TIMESHARE) {
-                       sched_background_decr(thread);
-               }
-
-               assert_thread_sched_count(thread);
-
-       }
-
-       assert_thread_sched_count(thread);
-}