2 * Copyright (c) 2001 Jake Burkholder <jake@FreeBSD.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 If there are N processors, then there are at most N KSEs (kernel
31 schedulable entities) working to process threads that belong to a
32 KSEGROUP (kg). If there are X of these KSEs actually running at the
33 moment in question, then there are at most M (N-X) of these KSEs on
34 the run queue, as running KSEs are not on the queue.
36 Runnable threads are queued off the KSEGROUP in priority order.
37 If there are M or more threads runnable, the top M threads
38 (by priority) are 'preassigned' to the M KSEs not running. The KSEs take
39 their priority from those threads and are put on the run queue.
41 The last thread that had a priority high enough to have a KSE associated
42 with it, AND IS ON THE RUN QUEUE is pointed to by
43 kg->kg_last_assigned. If no threads queued off the KSEGROUP have KSEs
44 assigned as all the available KSEs are activly running, or because there
45 are no threads queued, that pointer is NULL.
47 When a KSE is removed from the run queue to become runnable, we know
48 it was associated with the highest priority thread in the queue (at the head
49 of the queue). If it is also the last assigned we know M was 1 and must
50 now be 0. Since the thread is no longer queued that pointer must be
51 removed from it. Since we know there were no more KSEs available,
52 (M was 1 and is now 0) and since we are not FREEING our KSE
53 but using it, we know there are STILL no more KSEs available, we can prove
54 that the next thread in the ksegrp list will not have a KSE to assign to
55 it, so we can show that the pointer must be made 'invalid' (NULL).
57 The pointer exists so that when a new thread is made runnable, it can
58 have its priority compared with the last assigned thread to see if
59 it should 'steal' its KSE or not.. i.e. is it 'earlier'
60 on the list than that thread or later.. If it's earlier, then the KSE is
61 removed from the last assigned (which is now not assigned a KSE)
62 and reassigned to the new thread, which is placed earlier in the list.
63 The pointer is then backed up to the previous thread (which may or may not
66 When a thread sleeps or is removed, the KSE becomes available and if there
67 are queued threads that are not assigned KSEs, the highest priority one of
68 them is assigned the KSE, which is then placed back on the run queue at
69 the approipriate place, and the kg->kg_last_assigned pointer is adjusted down
72 The following diagram shows 2 KSEs and 3 threads from a single process.
74 RUNQ: --->KSE---KSE--... (KSEs queued at priorities from threads)
77 KSEGROUP---thread--thread--thread (queued in priority order)
82 The result of this scheme is that the M available KSEs are always
83 queued at the priorities they have inherrited from the M highest priority
84 threads for that KSEGROUP. If this situation changes, the KSEs are
85 reassigned to keep this true.
88 #include <sys/cdefs.h>
89 __FBSDID("$FreeBSD$");
91 #include "opt_sched.h"
93 #ifndef KERN_SWITCH_INCLUDE
94 #include <sys/param.h>
95 #include <sys/systm.h>
97 #include <sys/kernel.h>
100 #include <sys/mutex.h>
101 #include <sys/proc.h>
102 #include <sys/queue.h>
103 #include <sys/sched.h>
104 #else /* KERN_SWITCH_INCLUDE */
105 #if defined(SMP) && (defined(__i386__) || defined(__amd64__))
108 #if defined(SMP) && defined(SCHED_4BSD)
109 #include <sys/sysctl.h>
112 #ifdef FULL_PREEMPTION
114 #error "The FULL_PREEMPTION option requires the PREEMPTION option"
118 CTASSERT((RQB_BPW * RQB_LEN) == RQ_NQS);
120 #define td_kse td_sched
123 * kern.sched.preemption allows user space to determine if preemption support
124 * is compiled in or not. It is not currently a boot or runtime flag that
128 static int kern_sched_preemption = 1;
130 static int kern_sched_preemption = 0;
132 SYSCTL_INT(_kern_sched, OID_AUTO, preemption, CTLFLAG_RD,
133 &kern_sched_preemption, 0, "Kernel preemption enabled");
135 /************************************************************************
136 * Functions that manipulate runnability from a thread perspective. *
137 ************************************************************************/
139 * Select the KSE that will be run next. From that find the thread, and
140 * remove it from the KSEGRP's run queue. If there is thread clustering,
141 * this will be what does it.
150 #if defined(SMP) && (defined(__i386__) || defined(__amd64__))
151 if (smp_active == 0 && PCPU_GET(cpuid) != 0) {
152 /* Shutting down, run idlethread on AP's */
153 td = PCPU_GET(idlethread);
155 CTR1(KTR_RUNQ, "choosethread: td=%p (idle)", td);
156 ke->ke_flags |= KEF_DIDRUN;
166 KASSERT((td->td_kse == ke), ("kse/thread mismatch"));
168 if (td->td_proc->p_flag & P_HADTHREADS) {
169 if (kg->kg_last_assigned == td) {
170 kg->kg_last_assigned = TAILQ_PREV(td,
171 threadqueue, td_runq);
173 TAILQ_REMOVE(&kg->kg_runq, td, td_runq);
175 CTR2(KTR_RUNQ, "choosethread: td=%p pri=%d",
176 td, td->td_priority);
178 /* Simulate runq_choose() having returned the idle thread */
179 td = PCPU_GET(idlethread);
181 CTR1(KTR_RUNQ, "choosethread: td=%p (idle)", td);
183 ke->ke_flags |= KEF_DIDRUN;
186 * If we are in panic, only allow system threads,
187 * plus the one we are running in, to be run.
189 if (panicstr && ((td->td_proc->p_flag & P_SYSTEM) == 0 &&
190 (td->td_flags & TDF_INPANIC) == 0)) {
191 /* note that it is no longer on the run queue */
201 * Given a surplus system slot, try assign a new runnable thread to it.
203 * sched_thread_exit() (local)
204 * sched_switch() (local)
205 * sched_thread_exit() (local)
206 * remrunqueue() (local) (not at the moment)
209 slot_fill(struct ksegrp *kg)
213 mtx_assert(&sched_lock, MA_OWNED);
214 while (kg->kg_avail_opennings > 0) {
216 * Find the first unassigned thread
218 if ((td = kg->kg_last_assigned) != NULL)
219 td = TAILQ_NEXT(td, td_runq);
221 td = TAILQ_FIRST(&kg->kg_runq);
224 * If we found one, send it to the system scheduler.
227 kg->kg_last_assigned = td;
228 sched_add(td, SRQ_YIELDING);
229 CTR2(KTR_RUNQ, "slot_fill: td%p -> kg%p", td, kg);
231 /* no threads to use up the slots. quit now */
239 * Remove a thread from its KSEGRP's run queue.
240 * This in turn may remove it from a KSE if it was already assigned
241 * to one, possibly causing a new thread to be assigned to the KSE
242 * and the KSE getting a new priority.
245 remrunqueue(struct thread *td)
247 struct thread *td2, *td3;
251 mtx_assert(&sched_lock, MA_OWNED);
252 KASSERT((TD_ON_RUNQ(td)), ("remrunqueue: Bad state on run queue"));
255 CTR1(KTR_RUNQ, "remrunqueue: td%p", td);
258 * If it is not a threaded process, take the shortcut.
260 if ((td->td_proc->p_flag & P_HADTHREADS) == 0) {
261 /* remve from sys run queue and free up a slot */
263 ke->ke_state = KES_THREAD;
266 td3 = TAILQ_PREV(td, threadqueue, td_runq);
267 TAILQ_REMOVE(&kg->kg_runq, td, td_runq);
268 if (ke->ke_state == KES_ONRUNQ) {
270 * This thread has been assigned to the system run queue.
271 * We need to dissociate it and try assign the
272 * KSE to the next available thread. Then, we should
273 * see if we need to move the KSE in the run queues.
276 ke->ke_state = KES_THREAD;
277 td2 = kg->kg_last_assigned;
278 KASSERT((td2 != NULL), ("last assigned has wrong value"));
280 kg->kg_last_assigned = td3;
281 /* slot_fill(kg); */ /* will replace it with another */
287 * Change the priority of a thread that is on the run queue.
290 adjustrunqueue( struct thread *td, int newpri)
295 mtx_assert(&sched_lock, MA_OWNED);
296 KASSERT((TD_ON_RUNQ(td)), ("adjustrunqueue: Bad state on run queue"));
299 CTR1(KTR_RUNQ, "adjustrunqueue: td%p", td);
301 * If it is not a threaded process, take the shortcut.
303 if ((td->td_proc->p_flag & P_HADTHREADS) == 0) {
304 /* We only care about the kse in the run queue. */
305 td->td_priority = newpri;
306 if (ke->ke_rqindex != (newpri / RQ_PPQ)) {
308 sched_add(td, SRQ_BORING);
313 /* It is a threaded process */
315 if (ke->ke_state == KES_ONRUNQ) {
316 if (kg->kg_last_assigned == td) {
317 kg->kg_last_assigned =
318 TAILQ_PREV(td, threadqueue, td_runq);
322 TAILQ_REMOVE(&kg->kg_runq, td, td_runq);
324 td->td_priority = newpri;
325 setrunqueue(td, SRQ_BORING);
329 * This function is called when a thread is about to be put on a
330 * ksegrp run queue because it has been made runnable or its
331 * priority has been adjusted and the ksegrp does not have a
332 * free kse slot. It determines if a thread from the same ksegrp
333 * should be preempted. If so, it tries to switch threads
334 * if the thread is on the same cpu or notifies another cpu that
335 * it should switch threads.
339 maybe_preempt_in_ksegrp(struct thread *td)
342 struct thread *running_thread;
344 mtx_assert(&sched_lock, MA_OWNED);
345 running_thread = curthread;
347 if (running_thread->td_ksegrp != td->td_ksegrp)
350 if (td->td_priority >= running_thread->td_priority)
353 #ifndef FULL_PREEMPTION
354 if (td->td_priority > PRI_MAX_ITHD) {
355 running_thread->td_flags |= TDF_NEEDRESCHED;
358 #endif /* FULL_PREEMPTION */
360 if (running_thread->td_critnest > 1)
361 running_thread->td_owepreempt = 1;
363 mi_switch(SW_INVOL, NULL);
365 #else /* PREEMPTION */
366 running_thread->td_flags |= TDF_NEEDRESCHED;
367 #endif /* PREEMPTION */
373 struct thread *running_thread;
376 cpumask_t cpumask,dontuse;
378 struct pcpu *best_pcpu;
379 struct thread *cputhread;
381 mtx_assert(&sched_lock, MA_OWNED);
383 running_thread = curthread;
385 #if !defined(KSEG_PEEMPT_BEST_CPU)
386 if (running_thread->td_ksegrp != td->td_ksegrp) {
390 /* if someone is ahead of this thread, wait our turn */
391 if (td != TAILQ_FIRST(&kg->kg_runq))
394 worst_pri = td->td_priority;
396 dontuse = stopped_cpus | idle_cpus_mask;
399 * Find a cpu with the worst priority that runs at thread from
400 * the same ksegrp - if multiple exist give first the last run
401 * cpu and then the current cpu priority
404 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
405 cpumask = pc->pc_cpumask;
406 cputhread = pc->pc_curthread;
408 if ((cpumask & dontuse) ||
409 cputhread->td_ksegrp != kg)
412 if (cputhread->td_priority > worst_pri) {
413 worst_pri = cputhread->td_priority;
418 if (cputhread->td_priority == worst_pri &&
420 (td->td_lastcpu == pc->pc_cpuid ||
421 (PCPU_GET(cpumask) == cpumask &&
422 td->td_lastcpu != best_pcpu->pc_cpuid)))
426 /* Check if we need to preempt someone */
427 if (best_pcpu == NULL)
430 #if defined(IPI_PREEMPTION) && defined(PREEMPTION)
431 #if !defined(FULL_PREEMPTION)
432 if (td->td_priority <= PRI_MAX_ITHD)
433 #endif /* ! FULL_PREEMPTION */
435 ipi_selected(best_pcpu->pc_cpumask, IPI_PREEMPT);
438 #endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */
440 if (PCPU_GET(cpuid) != best_pcpu->pc_cpuid) {
441 best_pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED;
442 ipi_selected(best_pcpu->pc_cpumask, IPI_AST);
445 #if !defined(KSEG_PEEMPT_BEST_CPU)
449 if (td->td_priority >= running_thread->td_priority)
453 #if !defined(FULL_PREEMPTION)
454 if (td->td_priority > PRI_MAX_ITHD) {
455 running_thread->td_flags |= TDF_NEEDRESCHED;
457 #endif /* ! FULL_PREEMPTION */
459 if (running_thread->td_critnest > 1)
460 running_thread->td_owepreempt = 1;
462 mi_switch(SW_INVOL, NULL);
464 #else /* PREEMPTION */
465 running_thread->td_flags |= TDF_NEEDRESCHED;
466 #endif /* PREEMPTION */
474 setrunqueue(struct thread *td, int flags)
480 CTR3(KTR_RUNQ, "setrunqueue: td:%p kg:%p pid:%d",
481 td, td->td_ksegrp, td->td_proc->p_pid);
482 CTR5(KTR_SCHED, "setrunqueue: %p(%s) prio %d by %p(%s)",
483 td, td->td_proc->p_comm, td->td_priority, curthread,
484 curthread->td_proc->p_comm);
485 mtx_assert(&sched_lock, MA_OWNED);
486 KASSERT((td->td_inhibitors == 0),
487 ("setrunqueue: trying to run inhibitted thread"));
488 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
489 ("setrunqueue: bad thread state"));
492 if ((td->td_proc->p_flag & P_HADTHREADS) == 0) {
494 * Common path optimisation: Only one of everything
495 * and the KSE is always already attached.
496 * Totally ignore the ksegrp run queue.
498 if (kg->kg_avail_opennings != 1) {
499 if (limitcount < 1) {
501 printf("pid %d: corrected slot count (%d->1)\n",
502 td->td_proc->p_pid, kg->kg_avail_opennings);
505 kg->kg_avail_opennings = 1;
507 sched_add(td, flags);
512 * If the concurrency has reduced, and we would go in the
513 * assigned section, then keep removing entries from the
514 * system run queue, until we are not in that section
515 * or there is room for us to be put in that section.
516 * What we MUST avoid is the case where there are threads of less
517 * priority than the new one scheduled, but it can not
518 * be scheduled itself. That would lead to a non contiguous set
519 * of scheduled threads, and everything would break.
521 tda = kg->kg_last_assigned;
522 while ((kg->kg_avail_opennings <= 0) &&
523 (tda && (tda->td_priority > td->td_priority))) {
525 * None free, but there is one we can commandeer.
528 "setrunqueue: kg:%p: take slot from td: %p", kg, tda);
530 tda = kg->kg_last_assigned =
531 TAILQ_PREV(tda, threadqueue, td_runq);
535 * Add the thread to the ksegrp's run queue at
536 * the appropriate place.
538 TAILQ_FOREACH(td2, &kg->kg_runq, td_runq) {
539 if (td2->td_priority > td->td_priority) {
540 TAILQ_INSERT_BEFORE(td2, td, td_runq);
545 /* We ran off the end of the TAILQ or it was empty. */
546 TAILQ_INSERT_TAIL(&kg->kg_runq, td, td_runq);
550 * If we have a slot to use, then put the thread on the system
551 * run queue and if needed, readjust the last_assigned pointer.
552 * it may be that we need to schedule something anyhow
553 * even if the availabel slots are -ve so that
554 * all the items < last_assigned are scheduled.
556 if (kg->kg_avail_opennings > 0) {
559 * No pre-existing last assigned so whoever is first
560 * gets the slot.. (maybe us)
562 td2 = TAILQ_FIRST(&kg->kg_runq);
563 kg->kg_last_assigned = td2;
564 } else if (tda->td_priority > td->td_priority) {
568 * We are past last_assigned, so
569 * give the next slot to whatever is next,
570 * which may or may not be us.
572 td2 = TAILQ_NEXT(tda, td_runq);
573 kg->kg_last_assigned = td2;
575 sched_add(td2, flags);
577 CTR3(KTR_RUNQ, "setrunqueue: held: td%p kg%p pid%d",
578 td, td->td_ksegrp, td->td_proc->p_pid);
579 if ((flags & SRQ_YIELDING) == 0)
580 maybe_preempt_in_ksegrp(td);
585 * Kernel thread preemption implementation. Critical sections mark
586 * regions of code in which preemptions are not allowed.
595 CTR4(KTR_CRITICAL, "critical_enter by thread %p (%ld, %s) to %d", td,
596 (long)td->td_proc->p_pid, td->td_proc->p_comm, td->td_critnest);
605 KASSERT(td->td_critnest != 0,
606 ("critical_exit: td_critnest == 0"));
608 if (td->td_critnest == 1) {
610 mtx_assert(&sched_lock, MA_NOTOWNED);
611 if (td->td_owepreempt) {
613 mtx_lock_spin(&sched_lock);
615 mi_switch(SW_INVOL, NULL);
616 mtx_unlock_spin(&sched_lock);
623 CTR4(KTR_CRITICAL, "critical_exit by thread %p (%ld, %s) to %d", td,
624 (long)td->td_proc->p_pid, td->td_proc->p_comm, td->td_critnest);
628 * This function is called when a thread is about to be put on run queue
629 * because it has been made runnable or its priority has been adjusted. It
630 * determines if the new thread should be immediately preempted to. If so,
631 * it switches to it and eventually returns true. If not, it returns false
632 * so that the caller may place the thread on an appropriate run queue.
635 maybe_preempt(struct thread *td)
642 mtx_assert(&sched_lock, MA_OWNED);
645 * The new thread should not preempt the current thread if any of the
646 * following conditions are true:
648 * - The kernel is in the throes of crashing (panicstr).
649 * - The current thread has a higher (numerically lower) or
650 * equivalent priority. Note that this prevents curthread from
651 * trying to preempt to itself.
652 * - It is too early in the boot for context switches (cold is set).
653 * - The current thread has an inhibitor set or is in the process of
654 * exiting. In this case, the current thread is about to switch
655 * out anyways, so there's no point in preempting. If we did,
656 * the current thread would not be properly resumed as well, so
657 * just avoid that whole landmine.
658 * - If the new thread's priority is not a realtime priority and
659 * the current thread's priority is not an idle priority and
660 * FULL_PREEMPTION is disabled.
662 * If all of these conditions are false, but the current thread is in
663 * a nested critical section, then we have to defer the preemption
664 * until we exit the critical section. Otherwise, switch immediately
668 KASSERT ((ctd->td_kse != NULL && ctd->td_kse->ke_thread == ctd),
669 ("thread has no (or wrong) sched-private part."));
670 KASSERT((td->td_inhibitors == 0),
671 ("maybe_preempt: trying to run inhibitted thread"));
672 pri = td->td_priority;
673 cpri = ctd->td_priority;
674 if (panicstr != NULL || pri >= cpri || cold /* || dumping */ ||
675 TD_IS_INHIBITED(ctd) || td->td_kse->ke_state != KES_THREAD)
677 #ifndef FULL_PREEMPTION
678 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE)
682 if (ctd->td_critnest > 1) {
683 CTR1(KTR_PROC, "maybe_preempt: in critical section %d",
685 ctd->td_owepreempt = 1;
690 * Thread is runnable but not yet put on system run queue.
692 MPASS(TD_ON_RUNQ(td));
693 MPASS(td->td_sched->ke_state != KES_ONRUNQ);
694 if (td->td_proc->p_flag & P_HADTHREADS) {
696 * If this is a threaded process we actually ARE on the
697 * ksegrp run queue so take it off that first.
698 * Also undo any damage done to the last_assigned pointer.
699 * XXX Fix setrunqueue so this isn't needed
704 if (kg->kg_last_assigned == td)
705 kg->kg_last_assigned =
706 TAILQ_PREV(td, threadqueue, td_runq);
707 TAILQ_REMOVE(&kg->kg_runq, td, td_runq);
711 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td,
712 td->td_proc->p_pid, td->td_proc->p_comm);
713 mi_switch(SW_INVOL|SW_PREEMPT, td);
722 /* XXX: There should be a non-static version of this. */
724 printf_caddr_t(void *data)
726 printf("%s", (char *)data);
728 static char preempt_warning[] =
729 "WARNING: Kernel preemption is disabled, expect reduced performance.\n";
730 SYSINIT(preempt_warning, SI_SUB_COPYRIGHT, SI_ORDER_ANY, printf_caddr_t,
735 /************************************************************************
736 * SYSTEM RUN QUEUE manipulations and tests *
737 ************************************************************************/
739 * Initialize a run structure.
742 runq_init(struct runq *rq)
746 bzero(rq, sizeof *rq);
747 for (i = 0; i < RQ_NQS; i++)
748 TAILQ_INIT(&rq->rq_queues[i]);
752 * Clear the status bit of the queue corresponding to priority level pri,
753 * indicating that it is empty.
756 runq_clrbit(struct runq *rq, int pri)
760 rqb = &rq->rq_status;
761 CTR4(KTR_RUNQ, "runq_clrbit: bits=%#x %#x bit=%#x word=%d",
762 rqb->rqb_bits[RQB_WORD(pri)],
763 rqb->rqb_bits[RQB_WORD(pri)] & ~RQB_BIT(pri),
764 RQB_BIT(pri), RQB_WORD(pri));
765 rqb->rqb_bits[RQB_WORD(pri)] &= ~RQB_BIT(pri);
769 * Find the index of the first non-empty run queue. This is done by
770 * scanning the status bits, a set bit indicates a non-empty queue.
773 runq_findbit(struct runq *rq)
779 rqb = &rq->rq_status;
780 for (i = 0; i < RQB_LEN; i++)
781 if (rqb->rqb_bits[i]) {
782 pri = RQB_FFS(rqb->rqb_bits[i]) + (i << RQB_L2BPW);
783 CTR3(KTR_RUNQ, "runq_findbit: bits=%#x i=%d pri=%d",
784 rqb->rqb_bits[i], i, pri);
792 * Set the status bit of the queue corresponding to priority level pri,
793 * indicating that it is non-empty.
796 runq_setbit(struct runq *rq, int pri)
800 rqb = &rq->rq_status;
801 CTR4(KTR_RUNQ, "runq_setbit: bits=%#x %#x bit=%#x word=%d",
802 rqb->rqb_bits[RQB_WORD(pri)],
803 rqb->rqb_bits[RQB_WORD(pri)] | RQB_BIT(pri),
804 RQB_BIT(pri), RQB_WORD(pri));
805 rqb->rqb_bits[RQB_WORD(pri)] |= RQB_BIT(pri);
809 * Add the KSE to the queue specified by its priority, and set the
810 * corresponding status bit.
813 runq_add(struct runq *rq, struct kse *ke, int flags)
818 pri = ke->ke_thread->td_priority / RQ_PPQ;
819 ke->ke_rqindex = pri;
820 runq_setbit(rq, pri);
821 rqh = &rq->rq_queues[pri];
822 CTR5(KTR_RUNQ, "runq_add: td=%p ke=%p pri=%d %d rqh=%p",
823 ke->ke_thread, ke, ke->ke_thread->td_priority, pri, rqh);
824 if (flags & SRQ_PREEMPTED) {
825 TAILQ_INSERT_HEAD(rqh, ke, ke_procq);
827 TAILQ_INSERT_TAIL(rqh, ke, ke_procq);
832 * Return true if there are runnable processes of any priority on the run
833 * queue, false otherwise. Has no side effects, does not modify the run
837 runq_check(struct runq *rq)
842 rqb = &rq->rq_status;
843 for (i = 0; i < RQB_LEN; i++)
844 if (rqb->rqb_bits[i]) {
845 CTR2(KTR_RUNQ, "runq_check: bits=%#x i=%d",
846 rqb->rqb_bits[i], i);
849 CTR0(KTR_RUNQ, "runq_check: empty");
854 #if defined(SMP) && defined(SCHED_4BSD)
856 SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, "");
860 * Find the highest priority process on the run queue.
863 runq_choose(struct runq *rq)
869 mtx_assert(&sched_lock, MA_OWNED);
870 while ((pri = runq_findbit(rq)) != -1) {
871 rqh = &rq->rq_queues[pri];
872 #if defined(SMP) && defined(SCHED_4BSD)
873 /* fuzz == 1 is normal.. 0 or less are ignored */
876 * In the first couple of entries, check if
877 * there is one for our CPU as a preference.
879 int count = runq_fuzz;
880 int cpu = PCPU_GET(cpuid);
882 ke2 = ke = TAILQ_FIRST(rqh);
884 while (count-- && ke2) {
885 if (ke->ke_thread->td_lastcpu == cpu) {
889 ke2 = TAILQ_NEXT(ke2, ke_procq);
893 ke = TAILQ_FIRST(rqh);
894 KASSERT(ke != NULL, ("runq_choose: no proc on busy queue"));
896 "runq_choose: pri=%d kse=%p rqh=%p", pri, ke, rqh);
899 CTR1(KTR_RUNQ, "runq_choose: idleproc pri=%d", pri);
905 * Remove the KSE from the queue specified by its priority, and clear the
906 * corresponding status bit if the queue becomes empty.
907 * Caller must set ke->ke_state afterwards.
910 runq_remove(struct runq *rq, struct kse *ke)
915 KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
916 ("runq_remove: process swapped out"));
917 pri = ke->ke_rqindex;
918 rqh = &rq->rq_queues[pri];
919 CTR5(KTR_RUNQ, "runq_remove: td=%p, ke=%p pri=%d %d rqh=%p",
920 ke->ke_thread, ke, ke->ke_thread->td_priority, pri, rqh);
921 KASSERT(ke != NULL, ("runq_remove: no proc on busy queue"));
922 TAILQ_REMOVE(rqh, ke, ke_procq);
923 if (TAILQ_EMPTY(rqh)) {
924 CTR0(KTR_RUNQ, "runq_remove: empty");
925 runq_clrbit(rq, pri);
929 /****** functions that are temporarily here ***********/
931 extern struct mtx kse_zombie_lock;
934 * Allocate scheduler specific per-process resources.
935 * The thread and ksegrp have already been linked in.
936 * In this case just set the default concurrency value.
939 * proc_init() (UMA init method)
942 sched_newproc(struct proc *p, struct ksegrp *kg, struct thread *td)
945 /* This can go in sched_fork */
946 sched_init_concurrency(kg);
950 * thread is being either created or recycled.
951 * Fix up the per-scheduler resources associated with it.
953 * sched_fork_thread()
954 * thread_dtor() (*may go away)
955 * thread_init() (*may go away)
958 sched_newthread(struct thread *td)
962 ke = (struct td_sched *) (td + 1);
963 bzero(ke, sizeof(*ke));
966 ke->ke_state = KES_THREAD;
970 * Set up an initial concurrency of 1
971 * and set the given thread (if given) to be using that
973 * May be used "offline"..before the ksegrp is attached to the world
974 * and thus wouldn't need schedlock in that case.
977 * proc_init() (UMA) via sched_newproc()
980 sched_init_concurrency(struct ksegrp *kg)
983 CTR1(KTR_RUNQ,"kg %p init slots and concurrency to 1", kg);
984 kg->kg_concurrency = 1;
985 kg->kg_avail_opennings = 1;
989 * Change the concurrency of an existing ksegrp to N
997 sched_set_concurrency(struct ksegrp *kg, int concurrency)
1000 CTR4(KTR_RUNQ,"kg %p set concurrency to %d, slots %d -> %d",
1003 kg->kg_avail_opennings,
1004 kg->kg_avail_opennings + (concurrency - kg->kg_concurrency));
1005 kg->kg_avail_opennings += (concurrency - kg->kg_concurrency);
1006 kg->kg_concurrency = concurrency;
1010 * Called from thread_exit() for all exiting thread
1012 * Not to be confused with sched_exit_thread()
1013 * that is only called from thread_exit() for threads exiting
1014 * without the rest of the process exiting because it is also called from
1015 * sched_exit() and we wouldn't want to call it twice.
1016 * XXX This can probably be fixed.
1019 sched_thread_exit(struct thread *td)
1022 SLOT_RELEASE(td->td_ksegrp);
1023 slot_fill(td->td_ksegrp);
1026 #endif /* KERN_SWITCH_INCLUDE */