165
166static void
167setup_runqs(void)
168{
169#ifdef SMP
170 int i;
171
172 for (i = 0; i < MAXCPU; ++i)
173 runq_init(&runq_pcpu[i]);
174#endif
175
176 runq_init(&runq);
177}
178
179static int
180sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
181{
182 int error, new_val;
183
184 new_val = sched_quantum * tick;
185 error = sysctl_handle_int(oidp, &new_val, 0, req);
186 if (error != 0 || req->newptr == NULL)
187 return (error);
188 if (new_val < tick)
189 return (EINVAL);
190 sched_quantum = new_val / tick;
191 hogticks = 2 * sched_quantum;
192 return (0);
193}
194
195SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler");
196
197SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0,
198 "Scheduler name");
199
200SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
201 0, sizeof sched_quantum, sysctl_kern_quantum, "I",
202 "Roundrobin scheduling quantum in microseconds");
203
204#ifdef SMP
205/* Enable forwarding of wakeups to all other cpus */
206SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP");
207
208static int runq_fuzz = 1;
209SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, "");
210
211static int forward_wakeup_enabled = 1;
212SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW,
213 &forward_wakeup_enabled, 0,
214 "Forwarding of wakeup to idle CPUs");
215
216static int forward_wakeups_requested = 0;
217SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD,
218 &forward_wakeups_requested, 0,
219 "Requests for Forwarding of wakeup to idle CPUs");
220
221static int forward_wakeups_delivered = 0;
222SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD,
223 &forward_wakeups_delivered, 0,
224 "Completed Forwarding of wakeup to idle CPUs");
225
226static int forward_wakeup_use_mask = 1;
227SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW,
228 &forward_wakeup_use_mask, 0,
229 "Use the mask of idle cpus");
230
231static int forward_wakeup_use_loop = 0;
232SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW,
233 &forward_wakeup_use_loop, 0,
234 "Use a loop to find idle cpus");
235
236static int forward_wakeup_use_single = 0;
237SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, onecpu, CTLFLAG_RW,
238 &forward_wakeup_use_single, 0,
239 "Only signal one idle cpu");
240
241static int forward_wakeup_use_htt = 0;
242SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, htt2, CTLFLAG_RW,
243 &forward_wakeup_use_htt, 0,
244 "account for htt");
245
246#endif
247#if 0
248static int sched_followon = 0;
249SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW,
250 &sched_followon, 0,
251 "allow threads to share a quantum");
252#endif
253
254static __inline void
255sched_load_add(void)
256{
257
258 sched_tdcnt++;
259 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
260}
261
262static __inline void
263sched_load_rem(void)
264{
265
266 sched_tdcnt--;
267 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
268}
269/*
270 * Arrange to reschedule if necessary, taking the priorities and
271 * schedulers into account.
272 */
273static void
274maybe_resched(struct thread *td)
275{
276
277 THREAD_LOCK_ASSERT(td, MA_OWNED);
278 if (td->td_priority < curthread->td_priority)
279 curthread->td_flags |= TDF_NEEDRESCHED;
280}
281
282/*
283 * This function is called when a thread is about to be put on run queue
284 * because it has been made runnable or its priority has been adjusted. It
285 * determines if the new thread should be immediately preempted to. If so,
286 * it switches to it and eventually returns true. If not, it returns false
287 * so that the caller may place the thread on an appropriate run queue.
288 */
289int
290maybe_preempt(struct thread *td)
291{
292#ifdef PREEMPTION
293 struct thread *ctd;
294 int cpri, pri;
295
296 /*
297 * The new thread should not preempt the current thread if any of the
298 * following conditions are true:
299 *
300 * - The kernel is in the throes of crashing (panicstr).
301 * - The current thread has a higher (numerically lower) or
302 * equivalent priority. Note that this prevents curthread from
303 * trying to preempt to itself.
304 * - It is too early in the boot for context switches (cold is set).
305 * - The current thread has an inhibitor set or is in the process of
306 * exiting. In this case, the current thread is about to switch
307 * out anyways, so there's no point in preempting. If we did,
308 * the current thread would not be properly resumed as well, so
309 * just avoid that whole landmine.
310 * - If the new thread's priority is not a realtime priority and
311 * the current thread's priority is not an idle priority and
312 * FULL_PREEMPTION is disabled.
313 *
314 * If all of these conditions are false, but the current thread is in
315 * a nested critical section, then we have to defer the preemption
316 * until we exit the critical section. Otherwise, switch immediately
317 * to the new thread.
318 */
319 ctd = curthread;
320 THREAD_LOCK_ASSERT(td, MA_OWNED);
321 KASSERT((td->td_inhibitors == 0),
322 ("maybe_preempt: trying to run inhibited thread"));
323 pri = td->td_priority;
324 cpri = ctd->td_priority;
325 if (panicstr != NULL || pri >= cpri || cold /* || dumping */ ||
326 TD_IS_INHIBITED(ctd))
327 return (0);
328#ifndef FULL_PREEMPTION
329 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE)
330 return (0);
331#endif
332
333 if (ctd->td_critnest > 1) {
334 CTR1(KTR_PROC, "maybe_preempt: in critical section %d",
335 ctd->td_critnest);
336 ctd->td_owepreempt = 1;
337 return (0);
338 }
339 /*
340 * Thread is runnable but not yet put on system run queue.
341 */
342 MPASS(ctd->td_lock == td->td_lock);
343 MPASS(TD_ON_RUNQ(td));
344 TD_SET_RUNNING(td);
345 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td,
346 td->td_proc->p_pid, td->td_name);
347 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td);
348 /*
349 * td's lock pointer may have changed. We have to return with it
350 * locked.
351 */
352 spinlock_enter();
353 thread_unlock(ctd);
354 thread_lock(td);
355 spinlock_exit();
356 return (1);
357#else
358 return (0);
359#endif
360}
361
362/*
363 * Constants for digital decay and forget:
364 * 90% of (td_estcpu) usage in 5 * loadav time
365 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive)
366 * Note that, as ps(1) mentions, this can let percentages
367 * total over 100% (I've seen 137.9% for 3 processes).
368 *
369 * Note that schedclock() updates td_estcpu and p_cpticks asynchronously.
370 *
371 * We wish to decay away 90% of td_estcpu in (5 * loadavg) seconds.
372 * That is, the system wants to compute a value of decay such
373 * that the following for loop:
374 * for (i = 0; i < (5 * loadavg); i++)
375 * td_estcpu *= decay;
376 * will compute
377 * td_estcpu *= 0.1;
378 * for all values of loadavg:
379 *
380 * Mathematically this loop can be expressed by saying:
381 * decay ** (5 * loadavg) ~= .1
382 *
383 * The system computes decay as:
384 * decay = (2 * loadavg) / (2 * loadavg + 1)
385 *
386 * We wish to prove that the system's computation of decay
387 * will always fulfill the equation:
388 * decay ** (5 * loadavg) ~= .1
389 *
390 * If we compute b as:
391 * b = 2 * loadavg
392 * then
393 * decay = b / (b + 1)
394 *
395 * We now need to prove two things:
396 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
397 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
398 *
399 * Facts:
400 * For x close to zero, exp(x) =~ 1 + x, since
401 * exp(x) = 0! + x**1/1! + x**2/2! + ... .
402 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
403 * For x close to zero, ln(1+x) =~ x, since
404 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1
405 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
406 * ln(.1) =~ -2.30
407 *
408 * Proof of (1):
409 * Solve (factor)**(power) =~ .1 given power (5*loadav):
410 * solving for factor,
411 * ln(factor) =~ (-2.30/5*loadav), or
412 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
413 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED
414 *
415 * Proof of (2):
416 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
417 * solving for power,
418 * power*ln(b/(b+1)) =~ -2.30, or
419 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED
420 *
421 * Actual power values for the implemented algorithm are as follows:
422 * loadav: 1 2 3 4
423 * power: 5.68 10.32 14.94 19.55
424 */
425
426/* calculations for digital decay to forget 90% of usage in 5*loadav sec */
427#define loadfactor(loadav) (2 * (loadav))
428#define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE))
429
430/* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
431static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
432SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
433
434/*
435 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
436 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
437 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
438 *
439 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
440 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
441 *
442 * If you don't want to bother with the faster/more-accurate formula, you
443 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
444 * (more general) method of calculating the %age of CPU used by a process.
445 */
446#define CCPU_SHIFT 11
447
448/*
449 * Recompute process priorities, every hz ticks.
450 * MP-safe, called without the Giant mutex.
451 */
452/* ARGSUSED */
453static void
454schedcpu(void)
455{
456 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
457 struct thread *td;
458 struct proc *p;
459 struct td_sched *ts;
460 int awake, realstathz;
461
462 realstathz = stathz ? stathz : hz;
463 sx_slock(&allproc_lock);
464 FOREACH_PROC_IN_SYSTEM(p) {
465 PROC_LOCK(p);
466 FOREACH_THREAD_IN_PROC(p, td) {
467 awake = 0;
468 thread_lock(td);
469 ts = td->td_sched;
470 /*
471 * Increment sleep time (if sleeping). We
472 * ignore overflow, as above.
473 */
474 /*
475 * The td_sched slptimes are not touched in wakeup
476 * because the thread may not HAVE everything in
477 * memory? XXX I think this is out of date.
478 */
479 if (TD_ON_RUNQ(td)) {
480 awake = 1;
481 td->td_flags &= ~TDF_DIDRUN;
482 } else if (TD_IS_RUNNING(td)) {
483 awake = 1;
484 /* Do not clear TDF_DIDRUN */
485 } else if (td->td_flags & TDF_DIDRUN) {
486 awake = 1;
487 td->td_flags &= ~TDF_DIDRUN;
488 }
489
490 /*
491 * ts_pctcpu is only for ps and ttyinfo().
492 */
493 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT;
494 /*
495 * If the td_sched has been idle the entire second,
496 * stop recalculating its priority until
497 * it wakes up.
498 */
499 if (ts->ts_cpticks != 0) {
500#if (FSHIFT >= CCPU_SHIFT)
501 ts->ts_pctcpu += (realstathz == 100)
502 ? ((fixpt_t) ts->ts_cpticks) <<
503 (FSHIFT - CCPU_SHIFT) :
504 100 * (((fixpt_t) ts->ts_cpticks)
505 << (FSHIFT - CCPU_SHIFT)) / realstathz;
506#else
507 ts->ts_pctcpu += ((FSCALE - ccpu) *
508 (ts->ts_cpticks *
509 FSCALE / realstathz)) >> FSHIFT;
510#endif
511 ts->ts_cpticks = 0;
512 }
513 /*
514 * If there are ANY running threads in this process,
515 * then don't count it as sleeping.
516 * XXX: this is broken.
517 */
518 if (awake) {
519 if (ts->ts_slptime > 1) {
520 /*
521 * In an ideal world, this should not
522 * happen, because whoever woke us
523 * up from the long sleep should have
524 * unwound the slptime and reset our
525 * priority before we run at the stale
526 * priority. Should KASSERT at some
527 * point when all the cases are fixed.
528 */
529 updatepri(td);
530 }
531 ts->ts_slptime = 0;
532 } else
533 ts->ts_slptime++;
534 if (ts->ts_slptime > 1) {
535 thread_unlock(td);
536 continue;
537 }
538 td->td_estcpu = decay_cpu(loadfac, td->td_estcpu);
539 resetpriority(td);
540 resetpriority_thread(td);
541 thread_unlock(td);
542 }
543 PROC_UNLOCK(p);
544 }
545 sx_sunlock(&allproc_lock);
546}
547
548/*
549 * Main loop for a kthread that executes schedcpu once a second.
550 */
551static void
552schedcpu_thread(void)
553{
554
555 for (;;) {
556 schedcpu();
557 pause("-", hz);
558 }
559}
560
561/*
562 * Recalculate the priority of a process after it has slept for a while.
563 * For all load averages >= 1 and max td_estcpu of 255, sleeping for at
564 * least six times the loadfactor will decay td_estcpu to zero.
565 */
566static void
567updatepri(struct thread *td)
568{
569 struct td_sched *ts;
570 fixpt_t loadfac;
571 unsigned int newcpu;
572
573 ts = td->td_sched;
574 loadfac = loadfactor(averunnable.ldavg[0]);
575 if (ts->ts_slptime > 5 * loadfac)
576 td->td_estcpu = 0;
577 else {
578 newcpu = td->td_estcpu;
579 ts->ts_slptime--; /* was incremented in schedcpu() */
580 while (newcpu && --ts->ts_slptime)
581 newcpu = decay_cpu(loadfac, newcpu);
582 td->td_estcpu = newcpu;
583 }
584}
585
586/*
587 * Compute the priority of a process when running in user mode.
588 * Arrange to reschedule if the resulting priority is better
589 * than that of the current process.
590 */
591static void
592resetpriority(struct thread *td)
593{
594 register unsigned int newpriority;
595
596 if (td->td_pri_class == PRI_TIMESHARE) {
597 newpriority = PUSER + td->td_estcpu / INVERSE_ESTCPU_WEIGHT +
598 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN);
599 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE),
600 PRI_MAX_TIMESHARE);
601 sched_user_prio(td, newpriority);
602 }
603}
604
605/*
606 * Update the thread's priority when the associated process's user
607 * priority changes.
608 */
609static void
610resetpriority_thread(struct thread *td)
611{
612
613 /* Only change threads with a time sharing user priority. */
614 if (td->td_priority < PRI_MIN_TIMESHARE ||
615 td->td_priority > PRI_MAX_TIMESHARE)
616 return;
617
618 /* XXX the whole needresched thing is broken, but not silly. */
619 maybe_resched(td);
620
621 sched_prio(td, td->td_user_pri);
622}
623
624/* ARGSUSED */
625static void
626sched_setup(void *dummy)
627{
628 setup_runqs();
629
630 if (sched_quantum == 0)
631 sched_quantum = SCHED_QUANTUM;
632 hogticks = 2 * sched_quantum;
633
634 /* Account for thread0. */
635 sched_load_add();
636}
637
638/* External interfaces start here */
639
640/*
641 * Very early in the boot some setup of scheduler-specific
642 * parts of proc0 and of some scheduler resources needs to be done.
643 * Called from:
644 * proc0_init()
645 */
646void
647schedinit(void)
648{
649 /*
650 * Set up the scheduler specific parts of proc0.
651 */
652 proc0.p_sched = NULL; /* XXX */
653 thread0.td_sched = &td_sched0;
654 thread0.td_lock = &sched_lock;
655 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
656}
657
658int
659sched_runnable(void)
660{
661#ifdef SMP
662 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]);
663#else
664 return runq_check(&runq);
665#endif
666}
667
668int
669sched_rr_interval(void)
670{
671 if (sched_quantum == 0)
672 sched_quantum = SCHED_QUANTUM;
673 return (sched_quantum);
674}
675
676/*
677 * We adjust the priority of the current process. The priority of
678 * a process gets worse as it accumulates CPU time. The cpu usage
679 * estimator (td_estcpu) is increased here. resetpriority() will
680 * compute a different priority each time td_estcpu increases by
681 * INVERSE_ESTCPU_WEIGHT
682 * (until MAXPRI is reached). The cpu usage estimator ramps up
683 * quite quickly when the process is running (linearly), and decays
684 * away exponentially, at a rate which is proportionally slower when
685 * the system is busy. The basic principle is that the system will
686 * 90% forget that the process used a lot of CPU time in 5 * loadav
687 * seconds. This causes the system to favor processes which haven't
688 * run much recently, and to round-robin among other processes.
689 */
690void
691sched_clock(struct thread *td)
692{
693 struct pcpuidlestat *stat;
694 struct td_sched *ts;
695
696 THREAD_LOCK_ASSERT(td, MA_OWNED);
697 ts = td->td_sched;
698
699 ts->ts_cpticks++;
700 td->td_estcpu = ESTCPULIM(td->td_estcpu + 1);
701 if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
702 resetpriority(td);
703 resetpriority_thread(td);
704 }
705
706 /*
707 * Force a context switch if the current thread has used up a full
708 * quantum (default quantum is 100ms).
709 */
710 if (!TD_IS_IDLETHREAD(td) &&
711 ticks - PCPU_GET(switchticks) >= sched_quantum)
712 td->td_flags |= TDF_NEEDRESCHED;
713
714 stat = DPCPU_PTR(idlestat);
715 stat->oldidlecalls = stat->idlecalls;
716 stat->idlecalls = 0;
717}
718
719/*
720 * Charge child's scheduling CPU usage to parent.
721 */
722void
723sched_exit(struct proc *p, struct thread *td)
724{
725
726 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit",
727 "prio:td", td->td_priority);
728
729 PROC_LOCK_ASSERT(p, MA_OWNED);
730 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
731}
732
733void
734sched_exit_thread(struct thread *td, struct thread *child)
735{
736
737 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit",
738 "prio:td", child->td_priority);
739 thread_lock(td);
740 td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu);
741 thread_unlock(td);
742 thread_lock(child);
743 if ((child->td_flags & TDF_NOLOAD) == 0)
744 sched_load_rem();
745 thread_unlock(child);
746}
747
748void
749sched_fork(struct thread *td, struct thread *childtd)
750{
751 sched_fork_thread(td, childtd);
752}
753
754void
755sched_fork_thread(struct thread *td, struct thread *childtd)
756{
757 struct td_sched *ts;
758
759 childtd->td_estcpu = td->td_estcpu;
760 childtd->td_lock = &sched_lock;
761 childtd->td_cpuset = cpuset_ref(td->td_cpuset);
762 ts = childtd->td_sched;
763 bzero(ts, sizeof(*ts));
764 ts->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY);
765}
766
767void
768sched_nice(struct proc *p, int nice)
769{
770 struct thread *td;
771
772 PROC_LOCK_ASSERT(p, MA_OWNED);
773 p->p_nice = nice;
774 FOREACH_THREAD_IN_PROC(p, td) {
775 thread_lock(td);
776 resetpriority(td);
777 resetpriority_thread(td);
778 thread_unlock(td);
779 }
780}
781
782void
783sched_class(struct thread *td, int class)
784{
785 THREAD_LOCK_ASSERT(td, MA_OWNED);
786 td->td_pri_class = class;
787}
788
789/*
790 * Adjust the priority of a thread.
791 */
792static void
793sched_priority(struct thread *td, u_char prio)
794{
795
796
797 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change",
798 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED,
799 sched_tdname(curthread));
800 if (td != curthread && prio > td->td_priority) {
801 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
802 "lend prio", "prio:%d", td->td_priority, "new prio:%d",
803 prio, KTR_ATTR_LINKED, sched_tdname(td));
804 }
805 THREAD_LOCK_ASSERT(td, MA_OWNED);
806 if (td->td_priority == prio)
807 return;
808 td->td_priority = prio;
809 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) {
810 sched_rem(td);
811 sched_add(td, SRQ_BORING);
812 }
813}
814
815/*
816 * Update a thread's priority when it is lent another thread's
817 * priority.
818 */
819void
820sched_lend_prio(struct thread *td, u_char prio)
821{
822
823 td->td_flags |= TDF_BORROWING;
824 sched_priority(td, prio);
825}
826
827/*
828 * Restore a thread's priority when priority propagation is
829 * over. The prio argument is the minimum priority the thread
830 * needs to have to satisfy other possible priority lending
831 * requests. If the thread's regulary priority is less
832 * important than prio the thread will keep a priority boost
833 * of prio.
834 */
835void
836sched_unlend_prio(struct thread *td, u_char prio)
837{
838 u_char base_pri;
839
840 if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
841 td->td_base_pri <= PRI_MAX_TIMESHARE)
842 base_pri = td->td_user_pri;
843 else
844 base_pri = td->td_base_pri;
845 if (prio >= base_pri) {
846 td->td_flags &= ~TDF_BORROWING;
847 sched_prio(td, base_pri);
848 } else
849 sched_lend_prio(td, prio);
850}
851
852void
853sched_prio(struct thread *td, u_char prio)
854{
855 u_char oldprio;
856
857 /* First, update the base priority. */
858 td->td_base_pri = prio;
859
860 /*
861 * If the thread is borrowing another thread's priority, don't ever
862 * lower the priority.
863 */
864 if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
865 return;
866
867 /* Change the real priority. */
868 oldprio = td->td_priority;
869 sched_priority(td, prio);
870
871 /*
872 * If the thread is on a turnstile, then let the turnstile update
873 * its state.
874 */
875 if (TD_ON_LOCK(td) && oldprio != prio)
876 turnstile_adjust(td, oldprio);
877}
878
879void
880sched_user_prio(struct thread *td, u_char prio)
881{
882 u_char oldprio;
883
884 THREAD_LOCK_ASSERT(td, MA_OWNED);
885 td->td_base_user_pri = prio;
886 if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio)
887 return;
888 oldprio = td->td_user_pri;
889 td->td_user_pri = prio;
890}
891
892void
893sched_lend_user_prio(struct thread *td, u_char prio)
894{
895 u_char oldprio;
896
897 THREAD_LOCK_ASSERT(td, MA_OWNED);
898 td->td_flags |= TDF_UBORROWING;
899 oldprio = td->td_user_pri;
900 td->td_user_pri = prio;
901}
902
903void
904sched_unlend_user_prio(struct thread *td, u_char prio)
905{
906 u_char base_pri;
907
908 THREAD_LOCK_ASSERT(td, MA_OWNED);
909 base_pri = td->td_base_user_pri;
910 if (prio >= base_pri) {
911 td->td_flags &= ~TDF_UBORROWING;
912 sched_user_prio(td, base_pri);
913 } else {
914 sched_lend_user_prio(td, prio);
915 }
916}
917
918void
919sched_sleep(struct thread *td, int pri)
920{
921
922 THREAD_LOCK_ASSERT(td, MA_OWNED);
923 td->td_slptick = ticks;
924 td->td_sched->ts_slptime = 0;
925 if (pri)
926 sched_prio(td, pri);
927 if (TD_IS_SUSPENDED(td) || pri >= PSOCK)
928 td->td_flags |= TDF_CANSWAP;
929}
930
931void
932sched_switch(struct thread *td, struct thread *newtd, int flags)
933{
934 struct mtx *tmtx;
935 struct td_sched *ts;
936 struct proc *p;
937
938 tmtx = NULL;
939 ts = td->td_sched;
940 p = td->td_proc;
941
942 THREAD_LOCK_ASSERT(td, MA_OWNED);
943
944 /*
945 * Switch to the sched lock to fix things up and pick
946 * a new thread.
947 * Block the td_lock in order to avoid breaking the critical path.
948 */
949 if (td->td_lock != &sched_lock) {
950 mtx_lock_spin(&sched_lock);
951 tmtx = thread_lock_block(td);
952 }
953
954 if ((td->td_flags & TDF_NOLOAD) == 0)
955 sched_load_rem();
956
957 if (newtd) {
958 MPASS(newtd->td_lock == &sched_lock);
959 newtd->td_flags |= (td->td_flags & TDF_NEEDRESCHED);
960 }
961
962 td->td_lastcpu = td->td_oncpu;
963 td->td_flags &= ~TDF_NEEDRESCHED;
964 td->td_owepreempt = 0;
965 td->td_oncpu = NOCPU;
966
967 /*
968 * At the last moment, if this thread is still marked RUNNING,
969 * then put it back on the run queue as it has not been suspended
970 * or stopped or any thing else similar. We never put the idle
971 * threads on the run queue, however.
972 */
973 if (td->td_flags & TDF_IDLETD) {
974 TD_SET_CAN_RUN(td);
975#ifdef SMP
976 idle_cpus_mask &= ~PCPU_GET(cpumask);
977#endif
978 } else {
979 if (TD_IS_RUNNING(td)) {
980 /* Put us back on the run queue. */
981 sched_add(td, (flags & SW_PREEMPT) ?
982 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
983 SRQ_OURSELF|SRQ_YIELDING);
984 }
985 }
986 if (newtd) {
987 /*
988 * The thread we are about to run needs to be counted
989 * as if it had been added to the run queue and selected.
990 * It came from:
991 * * A preemption
992 * * An upcall
993 * * A followon
994 */
995 KASSERT((newtd->td_inhibitors == 0),
996 ("trying to run inhibited thread"));
997 newtd->td_flags |= TDF_DIDRUN;
998 TD_SET_RUNNING(newtd);
999 if ((newtd->td_flags & TDF_NOLOAD) == 0)
1000 sched_load_add();
1001 } else {
1002 newtd = choosethread();
1003 MPASS(newtd->td_lock == &sched_lock);
1004 }
1005
1006 if (td != newtd) {
1007#ifdef HWPMC_HOOKS
1008 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1009 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1010#endif
1011 /* I feel sleepy */
1012 lock_profile_release_lock(&sched_lock.lock_object);
1013#ifdef KDTRACE_HOOKS
1014 /*
1015 * If DTrace has set the active vtime enum to anything
1016 * other than INACTIVE (0), then it should have set the
1017 * function to call.
1018 */
1019 if (dtrace_vtime_active)
1020 (*dtrace_vtime_switch_func)(newtd);
1021#endif
1022
1023 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock);
1024 lock_profile_obtain_lock_success(&sched_lock.lock_object,
1025 0, 0, __FILE__, __LINE__);
1026 /*
1027 * Where am I? What year is it?
1028 * We are in the same thread that went to sleep above,
1029 * but any amount of time may have passed. All our context
1030 * will still be available as will local variables.
1031 * PCPU values however may have changed as we may have
1032 * changed CPU so don't trust cached values of them.
1033 * New threads will go to fork_exit() instead of here
1034 * so if you change things here you may need to change
1035 * things there too.
1036 *
1037 * If the thread above was exiting it will never wake
1038 * up again here, so either it has saved everything it
1039 * needed to, or the thread_wait() or wait() will
1040 * need to reap it.
1041 */
1042#ifdef HWPMC_HOOKS
1043 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1044 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
1045#endif
1046 }
1047
1048#ifdef SMP
1049 if (td->td_flags & TDF_IDLETD)
1050 idle_cpus_mask |= PCPU_GET(cpumask);
1051#endif
1052 sched_lock.mtx_lock = (uintptr_t)td;
1053 td->td_oncpu = PCPU_GET(cpuid);
1054 MPASS(td->td_lock == &sched_lock);
1055}
1056
1057void
1058sched_wakeup(struct thread *td)
1059{
1060 struct td_sched *ts;
1061
1062 THREAD_LOCK_ASSERT(td, MA_OWNED);
1063 ts = td->td_sched;
1064 td->td_flags &= ~TDF_CANSWAP;
1065 if (ts->ts_slptime > 1) {
1066 updatepri(td);
1067 resetpriority(td);
1068 }
1069 td->td_slptick = 0;
1070 ts->ts_slptime = 0;
1071 sched_add(td, SRQ_BORING);
1072}
1073
1074#ifdef SMP
1075static int
1076forward_wakeup(int cpunum)
1077{
1078 struct pcpu *pc;
1079 cpumask_t dontuse, id, map, map2, map3, me;
1080
1081 mtx_assert(&sched_lock, MA_OWNED);
1082
1083 CTR0(KTR_RUNQ, "forward_wakeup()");
1084
1085 if ((!forward_wakeup_enabled) ||
1086 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0))
1087 return (0);
1088 if (!smp_started || cold || panicstr)
1089 return (0);
1090
1091 forward_wakeups_requested++;
1092
1093 /*
1094 * Check the idle mask we received against what we calculated
1095 * before in the old version.
1096 */
1097 me = PCPU_GET(cpumask);
1098
1099 /* Don't bother if we should be doing it ourself. */
1100 if ((me & idle_cpus_mask) && (cpunum == NOCPU || me == (1 << cpunum)))
1101 return (0);
1102
1103 dontuse = me | stopped_cpus | hlt_cpus_mask;
1104 map3 = 0;
1105 if (forward_wakeup_use_loop) {
1106 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
1107 id = pc->pc_cpumask;
1108 if ((id & dontuse) == 0 &&
1109 pc->pc_curthread == pc->pc_idlethread) {
1110 map3 |= id;
1111 }
1112 }
1113 }
1114
1115 if (forward_wakeup_use_mask) {
1116 map = 0;
1117 map = idle_cpus_mask & ~dontuse;
1118
1119 /* If they are both on, compare and use loop if different. */
1120 if (forward_wakeup_use_loop) {
1121 if (map != map3) {
1122 printf("map (%02X) != map3 (%02X)\n", map,
1123 map3);
1124 map = map3;
1125 }
1126 }
1127 } else {
1128 map = map3;
1129 }
1130
1131 /* If we only allow a specific CPU, then mask off all the others. */
1132 if (cpunum != NOCPU) {
1133 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum."));
1134 map &= (1 << cpunum);
1135 } else {
1136 /* Try choose an idle die. */
1137 if (forward_wakeup_use_htt) {
1138 map2 = (map & (map >> 1)) & 0x5555;
1139 if (map2) {
1140 map = map2;
1141 }
1142 }
1143
1144 /* Set only one bit. */
1145 if (forward_wakeup_use_single) {
1146 map = map & ((~map) + 1);
1147 }
1148 }
1149 if (map) {
1150 forward_wakeups_delivered++;
1151 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
1152 id = pc->pc_cpumask;
1153 if ((map & id) == 0)
1154 continue;
1155 if (cpu_idle_wakeup(pc->pc_cpuid))
1156 map &= ~id;
1157 }
1158 if (map)
1159 ipi_selected(map, IPI_AST);
1160 return (1);
1161 }
1162 if (cpunum == NOCPU)
1163 printf("forward_wakeup: Idle processor not found\n");
1164 return (0);
1165}
1166
1167static void
1168kick_other_cpu(int pri, int cpuid)
1169{
1170 struct pcpu *pcpu;
1171 int cpri;
1172
1173 pcpu = pcpu_find(cpuid);
1174 if (idle_cpus_mask & pcpu->pc_cpumask) {
1175 forward_wakeups_delivered++;
1176 if (!cpu_idle_wakeup(cpuid))
1177 ipi_cpu(cpuid, IPI_AST);
1178 return;
1179 }
1180
1181 cpri = pcpu->pc_curthread->td_priority;
1182 if (pri >= cpri)
1183 return;
1184
1185#if defined(IPI_PREEMPTION) && defined(PREEMPTION)
1186#if !defined(FULL_PREEMPTION)
1187 if (pri <= PRI_MAX_ITHD)
1188#endif /* ! FULL_PREEMPTION */
1189 {
1190 ipi_cpu(cpuid, IPI_PREEMPT);
1191 return;
1192 }
1193#endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */
1194
1195 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED;
1196 ipi_cpu(cpuid, IPI_AST);
1197 return;
1198}
1199#endif /* SMP */
1200
1201#ifdef SMP
1202static int
1203sched_pickcpu(struct thread *td)
1204{
1205 int best, cpu;
1206
1207 mtx_assert(&sched_lock, MA_OWNED);
1208
1209 if (THREAD_CAN_SCHED(td, td->td_lastcpu))
1210 best = td->td_lastcpu;
1211 else
1212 best = NOCPU;
1213 CPU_FOREACH(cpu) {
1214 if (!THREAD_CAN_SCHED(td, cpu))
1215 continue;
1216
1217 if (best == NOCPU)
1218 best = cpu;
1219 else if (runq_length[cpu] < runq_length[best])
1220 best = cpu;
1221 }
1222 KASSERT(best != NOCPU, ("no valid CPUs"));
1223
1224 return (best);
1225}
1226#endif
1227
1228void
1229sched_add(struct thread *td, int flags)
1230#ifdef SMP
1231{
1232 struct td_sched *ts;
1233 int forwarded = 0;
1234 int cpu;
1235 int single_cpu = 0;
1236
1237 ts = td->td_sched;
1238 THREAD_LOCK_ASSERT(td, MA_OWNED);
1239 KASSERT((td->td_inhibitors == 0),
1240 ("sched_add: trying to run inhibited thread"));
1241 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
1242 ("sched_add: bad thread state"));
1243 KASSERT(td->td_flags & TDF_INMEM,
1244 ("sched_add: thread swapped out"));
1245
1246 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
1247 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1248 sched_tdname(curthread));
1249 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
1250 KTR_ATTR_LINKED, sched_tdname(td));
1251
1252
1253 /*
1254 * Now that the thread is moving to the run-queue, set the lock
1255 * to the scheduler's lock.
1256 */
1257 if (td->td_lock != &sched_lock) {
1258 mtx_lock_spin(&sched_lock);
1259 thread_lock_set(td, &sched_lock);
1260 }
1261 TD_SET_RUNQ(td);
1262
1263 if (td->td_pinned != 0) {
1264 cpu = td->td_lastcpu;
1265 ts->ts_runq = &runq_pcpu[cpu];
1266 single_cpu = 1;
1267 CTR3(KTR_RUNQ,
1268 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
1269 cpu);
1270 } else if (td->td_flags & TDF_BOUND) {
1271 /* Find CPU from bound runq. */
1272 KASSERT(SKE_RUNQ_PCPU(ts),
1273 ("sched_add: bound td_sched not on cpu runq"));
1274 cpu = ts->ts_runq - &runq_pcpu[0];
1275 single_cpu = 1;
1276 CTR3(KTR_RUNQ,
1277 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
1278 cpu);
1279 } else if (ts->ts_flags & TSF_AFFINITY) {
1280 /* Find a valid CPU for our cpuset */
1281 cpu = sched_pickcpu(td);
1282 ts->ts_runq = &runq_pcpu[cpu];
1283 single_cpu = 1;
1284 CTR3(KTR_RUNQ,
1285 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
1286 cpu);
1287 } else {
1288 CTR2(KTR_RUNQ,
1289 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts,
1290 td);
1291 cpu = NOCPU;
1292 ts->ts_runq = &runq;
1293 }
1294
1295 if (single_cpu && (cpu != PCPU_GET(cpuid))) {
1296 kick_other_cpu(td->td_priority, cpu);
1297 } else {
1298 if (!single_cpu) {
1299 cpumask_t me = PCPU_GET(cpumask);
1300 cpumask_t idle = idle_cpus_mask & me;
1301
1302 if (!idle && ((flags & SRQ_INTR) == 0) &&
1303 (idle_cpus_mask & ~(hlt_cpus_mask | me)))
1304 forwarded = forward_wakeup(cpu);
1305 }
1306
1307 if (!forwarded) {
1308 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td))
1309 return;
1310 else
1311 maybe_resched(td);
1312 }
1313 }
1314
1315 if ((td->td_flags & TDF_NOLOAD) == 0)
1316 sched_load_add();
1317 runq_add(ts->ts_runq, td, flags);
1318 if (cpu != NOCPU)
1319 runq_length[cpu]++;
1320}
1321#else /* SMP */
1322{
1323 struct td_sched *ts;
1324
1325 ts = td->td_sched;
1326 THREAD_LOCK_ASSERT(td, MA_OWNED);
1327 KASSERT((td->td_inhibitors == 0),
1328 ("sched_add: trying to run inhibited thread"));
1329 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
1330 ("sched_add: bad thread state"));
1331 KASSERT(td->td_flags & TDF_INMEM,
1332 ("sched_add: thread swapped out"));
1333 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
1334 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1335 sched_tdname(curthread));
1336 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
1337 KTR_ATTR_LINKED, sched_tdname(td));
1338
1339 /*
1340 * Now that the thread is moving to the run-queue, set the lock
1341 * to the scheduler's lock.
1342 */
1343 if (td->td_lock != &sched_lock) {
1344 mtx_lock_spin(&sched_lock);
1345 thread_lock_set(td, &sched_lock);
1346 }
1347 TD_SET_RUNQ(td);
1348 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td);
1349 ts->ts_runq = &runq;
1350
1351 /*
1352 * If we are yielding (on the way out anyhow) or the thread
1353 * being saved is US, then don't try be smart about preemption
1354 * or kicking off another CPU as it won't help and may hinder.
1355 * In the YIEDLING case, we are about to run whoever is being
1356 * put in the queue anyhow, and in the OURSELF case, we are
1357 * puting ourself on the run queue which also only happens
1358 * when we are about to yield.
1359 */
1360 if ((flags & SRQ_YIELDING) == 0) {
1361 if (maybe_preempt(td))
1362 return;
1363 }
1364 if ((td->td_flags & TDF_NOLOAD) == 0)
1365 sched_load_add();
1366 runq_add(ts->ts_runq, td, flags);
1367 maybe_resched(td);
1368}
1369#endif /* SMP */
1370
1371void
1372sched_rem(struct thread *td)
1373{
1374 struct td_sched *ts;
1375
1376 ts = td->td_sched;
1377 KASSERT(td->td_flags & TDF_INMEM,
1378 ("sched_rem: thread swapped out"));
1379 KASSERT(TD_ON_RUNQ(td),
1380 ("sched_rem: thread not on run queue"));
1381 mtx_assert(&sched_lock, MA_OWNED);
1382 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
1383 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1384 sched_tdname(curthread));
1385
1386 if ((td->td_flags & TDF_NOLOAD) == 0)
1387 sched_load_rem();
1388#ifdef SMP
1389 if (ts->ts_runq != &runq)
1390 runq_length[ts->ts_runq - runq_pcpu]--;
1391#endif
1392 runq_remove(ts->ts_runq, td);
1393 TD_SET_CAN_RUN(td);
1394}
1395
1396/*
1397 * Select threads to run. Note that running threads still consume a
1398 * slot.
1399 */
1400struct thread *
1401sched_choose(void)
1402{
1403 struct thread *td;
1404 struct runq *rq;
1405
1406 mtx_assert(&sched_lock, MA_OWNED);
1407#ifdef SMP
1408 struct thread *tdcpu;
1409
1410 rq = &runq;
1411 td = runq_choose_fuzz(&runq, runq_fuzz);
1412 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]);
1413
1414 if (td == NULL ||
1415 (tdcpu != NULL &&
1416 tdcpu->td_priority < td->td_priority)) {
1417 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu,
1418 PCPU_GET(cpuid));
1419 td = tdcpu;
1420 rq = &runq_pcpu[PCPU_GET(cpuid)];
1421 } else {
1422 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td);
1423 }
1424
1425#else
1426 rq = &runq;
1427 td = runq_choose(&runq);
1428#endif
1429
1430 if (td) {
1431#ifdef SMP
1432 if (td == tdcpu)
1433 runq_length[PCPU_GET(cpuid)]--;
1434#endif
1435 runq_remove(rq, td);
1436 td->td_flags |= TDF_DIDRUN;
1437
1438 KASSERT(td->td_flags & TDF_INMEM,
1439 ("sched_choose: thread swapped out"));
1440 return (td);
1441 }
1442 return (PCPU_GET(idlethread));
1443}
1444
1445void
1446sched_preempt(struct thread *td)
1447{
1448 thread_lock(td);
1449 if (td->td_critnest > 1)
1450 td->td_owepreempt = 1;
1451 else
1452 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL);
1453 thread_unlock(td);
1454}
1455
1456void
1457sched_userret(struct thread *td)
1458{
1459 /*
1460 * XXX we cheat slightly on the locking here to avoid locking in
1461 * the usual case. Setting td_priority here is essentially an
1462 * incomplete workaround for not setting it properly elsewhere.
1463 * Now that some interrupt handlers are threads, not setting it
1464 * properly elsewhere can clobber it in the window between setting
1465 * it here and returning to user mode, so don't waste time setting
1466 * it perfectly here.
1467 */
1468 KASSERT((td->td_flags & TDF_BORROWING) == 0,
1469 ("thread with borrowed priority returning to userland"));
1470 if (td->td_priority != td->td_user_pri) {
1471 thread_lock(td);
1472 td->td_priority = td->td_user_pri;
1473 td->td_base_pri = td->td_user_pri;
1474 thread_unlock(td);
1475 }
1476}
1477
1478void
1479sched_bind(struct thread *td, int cpu)
1480{
1481 struct td_sched *ts;
1482
1483 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
1484 KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
1485
1486 ts = td->td_sched;
1487
1488 td->td_flags |= TDF_BOUND;
1489#ifdef SMP
1490 ts->ts_runq = &runq_pcpu[cpu];
1491 if (PCPU_GET(cpuid) == cpu)
1492 return;
1493
1494 mi_switch(SW_VOL, NULL);
1495#endif
1496}
1497
1498void
1499sched_unbind(struct thread* td)
1500{
1501 THREAD_LOCK_ASSERT(td, MA_OWNED);
1502 KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
1503 td->td_flags &= ~TDF_BOUND;
1504}
1505
1506int
1507sched_is_bound(struct thread *td)
1508{
1509 THREAD_LOCK_ASSERT(td, MA_OWNED);
1510 return (td->td_flags & TDF_BOUND);
1511}
1512
1513void
1514sched_relinquish(struct thread *td)
1515{
1516 thread_lock(td);
1517 mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
1518 thread_unlock(td);
1519}
1520
1521int
1522sched_load(void)
1523{
1524 return (sched_tdcnt);
1525}
1526
1527int
1528sched_sizeof_proc(void)
1529{
1530 return (sizeof(struct proc));
1531}
1532
1533int
1534sched_sizeof_thread(void)
1535{
1536 return (sizeof(struct thread) + sizeof(struct td_sched));
1537}
1538
1539fixpt_t
1540sched_pctcpu(struct thread *td)
1541{
1542 struct td_sched *ts;
1543
1544 THREAD_LOCK_ASSERT(td, MA_OWNED);
1545 ts = td->td_sched;
1546 return (ts->ts_pctcpu);
1547}
1548
1549void
1550sched_tick(int cnt)
1551{
1552}
1553
1554/*
1555 * The actual idle process.
1556 */
1557void
1558sched_idletd(void *dummy)
1559{
1560 struct pcpuidlestat *stat;
1561
1562 stat = DPCPU_PTR(idlestat);
1563 for (;;) {
1564 mtx_assert(&Giant, MA_NOTOWNED);
1565
1566 while (sched_runnable() == 0) {
1567 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64);
1568 stat->idlecalls++;
1569 }
1570
1571 mtx_lock_spin(&sched_lock);
1572 mi_switch(SW_VOL | SWT_IDLE, NULL);
1573 mtx_unlock_spin(&sched_lock);
1574 }
1575}
1576
1577/*
1578 * A CPU is entering for the first time or a thread is exiting.
1579 */
1580void
1581sched_throw(struct thread *td)
1582{
1583 /*
1584 * Correct spinlock nesting. The idle thread context that we are
1585 * borrowing was created so that it would start out with a single
1586 * spin lock (sched_lock) held in fork_trampoline(). Since we've
1587 * explicitly acquired locks in this function, the nesting count
1588 * is now 2 rather than 1. Since we are nested, calling
1589 * spinlock_exit() will simply adjust the counts without allowing
1590 * spin lock using code to interrupt us.
1591 */
1592 if (td == NULL) {
1593 mtx_lock_spin(&sched_lock);
1594 spinlock_exit();
1595 } else {
1596 lock_profile_release_lock(&sched_lock.lock_object);
1597 MPASS(td->td_lock == &sched_lock);
1598 }
1599 mtx_assert(&sched_lock, MA_OWNED);
1600 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
1601 PCPU_SET(switchtime, cpu_ticks());
1602 PCPU_SET(switchticks, ticks);
1603 cpu_throw(td, choosethread()); /* doesn't return */
1604}
1605
1606void
1607sched_fork_exit(struct thread *td)
1608{
1609
1610 /*
1611 * Finish setting up thread glue so that it begins execution in a
1612 * non-nested critical section with sched_lock held but not recursed.
1613 */
1614 td->td_oncpu = PCPU_GET(cpuid);
1615 sched_lock.mtx_lock = (uintptr_t)td;
1616 lock_profile_obtain_lock_success(&sched_lock.lock_object,
1617 0, 0, __FILE__, __LINE__);
1618 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
1619}
1620
1621char *
1622sched_tdname(struct thread *td)
1623{
1624#ifdef KTR
1625 struct td_sched *ts;
1626
1627 ts = td->td_sched;
1628 if (ts->ts_name[0] == '\0')
1629 snprintf(ts->ts_name, sizeof(ts->ts_name),
1630 "%s tid %d", td->td_name, td->td_tid);
1631 return (ts->ts_name);
1632#else
1633 return (td->td_name);
1634#endif
1635}
1636
1637void
1638sched_affinity(struct thread *td)
1639{
1640#ifdef SMP
1641 struct td_sched *ts;
1642 int cpu;
1643
1644 THREAD_LOCK_ASSERT(td, MA_OWNED);
1645
1646 /*
1647 * Set the TSF_AFFINITY flag if there is at least one CPU this
1648 * thread can't run on.
1649 */
1650 ts = td->td_sched;
1651 ts->ts_flags &= ~TSF_AFFINITY;
1652 CPU_FOREACH(cpu) {
1653 if (!THREAD_CAN_SCHED(td, cpu)) {
1654 ts->ts_flags |= TSF_AFFINITY;
1655 break;
1656 }
1657 }
1658
1659 /*
1660 * If this thread can run on all CPUs, nothing else to do.
1661 */
1662 if (!(ts->ts_flags & TSF_AFFINITY))
1663 return;
1664
1665 /* Pinned threads and bound threads should be left alone. */
1666 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND)
1667 return;
1668
1669 switch (td->td_state) {
1670 case TDS_RUNQ:
1671 /*
1672 * If we are on a per-CPU runqueue that is in the set,
1673 * then nothing needs to be done.
1674 */
1675 if (ts->ts_runq != &runq &&
1676 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu))
1677 return;
1678
1679 /* Put this thread on a valid per-CPU runqueue. */
1680 sched_rem(td);
1681 sched_add(td, SRQ_BORING);
1682 break;
1683 case TDS_RUNNING:
1684 /*
1685 * See if our current CPU is in the set. If not, force a
1686 * context switch.
1687 */
1688 if (THREAD_CAN_SCHED(td, td->td_oncpu))
1689 return;
1690
1691 td->td_flags |= TDF_NEEDRESCHED;
1692 if (td != curthread)
1693 ipi_cpu(cpu, IPI_AST);
1694 break;
1695 default:
1696 break;
1697 }
1698#endif
1699}
| 165
166static void
167setup_runqs(void)
168{
169#ifdef SMP
170 int i;
171
172 for (i = 0; i < MAXCPU; ++i)
173 runq_init(&runq_pcpu[i]);
174#endif
175
176 runq_init(&runq);
177}
178
179static int
180sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
181{
182 int error, new_val;
183
184 new_val = sched_quantum * tick;
185 error = sysctl_handle_int(oidp, &new_val, 0, req);
186 if (error != 0 || req->newptr == NULL)
187 return (error);
188 if (new_val < tick)
189 return (EINVAL);
190 sched_quantum = new_val / tick;
191 hogticks = 2 * sched_quantum;
192 return (0);
193}
194
195SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler");
196
197SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0,
198 "Scheduler name");
199
200SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
201 0, sizeof sched_quantum, sysctl_kern_quantum, "I",
202 "Roundrobin scheduling quantum in microseconds");
203
204#ifdef SMP
205/* Enable forwarding of wakeups to all other cpus */
206SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP");
207
208static int runq_fuzz = 1;
209SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, "");
210
211static int forward_wakeup_enabled = 1;
212SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW,
213 &forward_wakeup_enabled, 0,
214 "Forwarding of wakeup to idle CPUs");
215
216static int forward_wakeups_requested = 0;
217SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD,
218 &forward_wakeups_requested, 0,
219 "Requests for Forwarding of wakeup to idle CPUs");
220
221static int forward_wakeups_delivered = 0;
222SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD,
223 &forward_wakeups_delivered, 0,
224 "Completed Forwarding of wakeup to idle CPUs");
225
226static int forward_wakeup_use_mask = 1;
227SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW,
228 &forward_wakeup_use_mask, 0,
229 "Use the mask of idle cpus");
230
231static int forward_wakeup_use_loop = 0;
232SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW,
233 &forward_wakeup_use_loop, 0,
234 "Use a loop to find idle cpus");
235
236static int forward_wakeup_use_single = 0;
237SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, onecpu, CTLFLAG_RW,
238 &forward_wakeup_use_single, 0,
239 "Only signal one idle cpu");
240
241static int forward_wakeup_use_htt = 0;
242SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, htt2, CTLFLAG_RW,
243 &forward_wakeup_use_htt, 0,
244 "account for htt");
245
246#endif
247#if 0
248static int sched_followon = 0;
249SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW,
250 &sched_followon, 0,
251 "allow threads to share a quantum");
252#endif
253
254static __inline void
255sched_load_add(void)
256{
257
258 sched_tdcnt++;
259 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
260}
261
262static __inline void
263sched_load_rem(void)
264{
265
266 sched_tdcnt--;
267 KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
268}
269/*
270 * Arrange to reschedule if necessary, taking the priorities and
271 * schedulers into account.
272 */
273static void
274maybe_resched(struct thread *td)
275{
276
277 THREAD_LOCK_ASSERT(td, MA_OWNED);
278 if (td->td_priority < curthread->td_priority)
279 curthread->td_flags |= TDF_NEEDRESCHED;
280}
281
282/*
283 * This function is called when a thread is about to be put on run queue
284 * because it has been made runnable or its priority has been adjusted. It
285 * determines if the new thread should be immediately preempted to. If so,
286 * it switches to it and eventually returns true. If not, it returns false
287 * so that the caller may place the thread on an appropriate run queue.
288 */
289int
290maybe_preempt(struct thread *td)
291{
292#ifdef PREEMPTION
293 struct thread *ctd;
294 int cpri, pri;
295
296 /*
297 * The new thread should not preempt the current thread if any of the
298 * following conditions are true:
299 *
300 * - The kernel is in the throes of crashing (panicstr).
301 * - The current thread has a higher (numerically lower) or
302 * equivalent priority. Note that this prevents curthread from
303 * trying to preempt to itself.
304 * - It is too early in the boot for context switches (cold is set).
305 * - The current thread has an inhibitor set or is in the process of
306 * exiting. In this case, the current thread is about to switch
307 * out anyways, so there's no point in preempting. If we did,
308 * the current thread would not be properly resumed as well, so
309 * just avoid that whole landmine.
310 * - If the new thread's priority is not a realtime priority and
311 * the current thread's priority is not an idle priority and
312 * FULL_PREEMPTION is disabled.
313 *
314 * If all of these conditions are false, but the current thread is in
315 * a nested critical section, then we have to defer the preemption
316 * until we exit the critical section. Otherwise, switch immediately
317 * to the new thread.
318 */
319 ctd = curthread;
320 THREAD_LOCK_ASSERT(td, MA_OWNED);
321 KASSERT((td->td_inhibitors == 0),
322 ("maybe_preempt: trying to run inhibited thread"));
323 pri = td->td_priority;
324 cpri = ctd->td_priority;
325 if (panicstr != NULL || pri >= cpri || cold /* || dumping */ ||
326 TD_IS_INHIBITED(ctd))
327 return (0);
328#ifndef FULL_PREEMPTION
329 if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE)
330 return (0);
331#endif
332
333 if (ctd->td_critnest > 1) {
334 CTR1(KTR_PROC, "maybe_preempt: in critical section %d",
335 ctd->td_critnest);
336 ctd->td_owepreempt = 1;
337 return (0);
338 }
339 /*
340 * Thread is runnable but not yet put on system run queue.
341 */
342 MPASS(ctd->td_lock == td->td_lock);
343 MPASS(TD_ON_RUNQ(td));
344 TD_SET_RUNNING(td);
345 CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td,
346 td->td_proc->p_pid, td->td_name);
347 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td);
348 /*
349 * td's lock pointer may have changed. We have to return with it
350 * locked.
351 */
352 spinlock_enter();
353 thread_unlock(ctd);
354 thread_lock(td);
355 spinlock_exit();
356 return (1);
357#else
358 return (0);
359#endif
360}
361
362/*
363 * Constants for digital decay and forget:
364 * 90% of (td_estcpu) usage in 5 * loadav time
365 * 95% of (ts_pctcpu) usage in 60 seconds (load insensitive)
366 * Note that, as ps(1) mentions, this can let percentages
367 * total over 100% (I've seen 137.9% for 3 processes).
368 *
369 * Note that schedclock() updates td_estcpu and p_cpticks asynchronously.
370 *
371 * We wish to decay away 90% of td_estcpu in (5 * loadavg) seconds.
372 * That is, the system wants to compute a value of decay such
373 * that the following for loop:
374 * for (i = 0; i < (5 * loadavg); i++)
375 * td_estcpu *= decay;
376 * will compute
377 * td_estcpu *= 0.1;
378 * for all values of loadavg:
379 *
380 * Mathematically this loop can be expressed by saying:
381 * decay ** (5 * loadavg) ~= .1
382 *
383 * The system computes decay as:
384 * decay = (2 * loadavg) / (2 * loadavg + 1)
385 *
386 * We wish to prove that the system's computation of decay
387 * will always fulfill the equation:
388 * decay ** (5 * loadavg) ~= .1
389 *
390 * If we compute b as:
391 * b = 2 * loadavg
392 * then
393 * decay = b / (b + 1)
394 *
395 * We now need to prove two things:
396 * 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
397 * 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
398 *
399 * Facts:
400 * For x close to zero, exp(x) =~ 1 + x, since
401 * exp(x) = 0! + x**1/1! + x**2/2! + ... .
402 * therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
403 * For x close to zero, ln(1+x) =~ x, since
404 * ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1
405 * therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
406 * ln(.1) =~ -2.30
407 *
408 * Proof of (1):
409 * Solve (factor)**(power) =~ .1 given power (5*loadav):
410 * solving for factor,
411 * ln(factor) =~ (-2.30/5*loadav), or
412 * factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
413 * exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED
414 *
415 * Proof of (2):
416 * Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
417 * solving for power,
418 * power*ln(b/(b+1)) =~ -2.30, or
419 * power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED
420 *
421 * Actual power values for the implemented algorithm are as follows:
422 * loadav: 1 2 3 4
423 * power: 5.68 10.32 14.94 19.55
424 */
425
426/* calculations for digital decay to forget 90% of usage in 5*loadav sec */
427#define loadfactor(loadav) (2 * (loadav))
428#define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE))
429
430/* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
431static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
432SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
433
434/*
435 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
436 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
437 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
438 *
439 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
440 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
441 *
442 * If you don't want to bother with the faster/more-accurate formula, you
443 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
444 * (more general) method of calculating the %age of CPU used by a process.
445 */
446#define CCPU_SHIFT 11
447
448/*
449 * Recompute process priorities, every hz ticks.
450 * MP-safe, called without the Giant mutex.
451 */
452/* ARGSUSED */
453static void
454schedcpu(void)
455{
456 register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
457 struct thread *td;
458 struct proc *p;
459 struct td_sched *ts;
460 int awake, realstathz;
461
462 realstathz = stathz ? stathz : hz;
463 sx_slock(&allproc_lock);
464 FOREACH_PROC_IN_SYSTEM(p) {
465 PROC_LOCK(p);
466 FOREACH_THREAD_IN_PROC(p, td) {
467 awake = 0;
468 thread_lock(td);
469 ts = td->td_sched;
470 /*
471 * Increment sleep time (if sleeping). We
472 * ignore overflow, as above.
473 */
474 /*
475 * The td_sched slptimes are not touched in wakeup
476 * because the thread may not HAVE everything in
477 * memory? XXX I think this is out of date.
478 */
479 if (TD_ON_RUNQ(td)) {
480 awake = 1;
481 td->td_flags &= ~TDF_DIDRUN;
482 } else if (TD_IS_RUNNING(td)) {
483 awake = 1;
484 /* Do not clear TDF_DIDRUN */
485 } else if (td->td_flags & TDF_DIDRUN) {
486 awake = 1;
487 td->td_flags &= ~TDF_DIDRUN;
488 }
489
490 /*
491 * ts_pctcpu is only for ps and ttyinfo().
492 */
493 ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT;
494 /*
495 * If the td_sched has been idle the entire second,
496 * stop recalculating its priority until
497 * it wakes up.
498 */
499 if (ts->ts_cpticks != 0) {
500#if (FSHIFT >= CCPU_SHIFT)
501 ts->ts_pctcpu += (realstathz == 100)
502 ? ((fixpt_t) ts->ts_cpticks) <<
503 (FSHIFT - CCPU_SHIFT) :
504 100 * (((fixpt_t) ts->ts_cpticks)
505 << (FSHIFT - CCPU_SHIFT)) / realstathz;
506#else
507 ts->ts_pctcpu += ((FSCALE - ccpu) *
508 (ts->ts_cpticks *
509 FSCALE / realstathz)) >> FSHIFT;
510#endif
511 ts->ts_cpticks = 0;
512 }
513 /*
514 * If there are ANY running threads in this process,
515 * then don't count it as sleeping.
516 * XXX: this is broken.
517 */
518 if (awake) {
519 if (ts->ts_slptime > 1) {
520 /*
521 * In an ideal world, this should not
522 * happen, because whoever woke us
523 * up from the long sleep should have
524 * unwound the slptime and reset our
525 * priority before we run at the stale
526 * priority. Should KASSERT at some
527 * point when all the cases are fixed.
528 */
529 updatepri(td);
530 }
531 ts->ts_slptime = 0;
532 } else
533 ts->ts_slptime++;
534 if (ts->ts_slptime > 1) {
535 thread_unlock(td);
536 continue;
537 }
538 td->td_estcpu = decay_cpu(loadfac, td->td_estcpu);
539 resetpriority(td);
540 resetpriority_thread(td);
541 thread_unlock(td);
542 }
543 PROC_UNLOCK(p);
544 }
545 sx_sunlock(&allproc_lock);
546}
547
548/*
549 * Main loop for a kthread that executes schedcpu once a second.
550 */
551static void
552schedcpu_thread(void)
553{
554
555 for (;;) {
556 schedcpu();
557 pause("-", hz);
558 }
559}
560
561/*
562 * Recalculate the priority of a process after it has slept for a while.
563 * For all load averages >= 1 and max td_estcpu of 255, sleeping for at
564 * least six times the loadfactor will decay td_estcpu to zero.
565 */
566static void
567updatepri(struct thread *td)
568{
569 struct td_sched *ts;
570 fixpt_t loadfac;
571 unsigned int newcpu;
572
573 ts = td->td_sched;
574 loadfac = loadfactor(averunnable.ldavg[0]);
575 if (ts->ts_slptime > 5 * loadfac)
576 td->td_estcpu = 0;
577 else {
578 newcpu = td->td_estcpu;
579 ts->ts_slptime--; /* was incremented in schedcpu() */
580 while (newcpu && --ts->ts_slptime)
581 newcpu = decay_cpu(loadfac, newcpu);
582 td->td_estcpu = newcpu;
583 }
584}
585
586/*
587 * Compute the priority of a process when running in user mode.
588 * Arrange to reschedule if the resulting priority is better
589 * than that of the current process.
590 */
591static void
592resetpriority(struct thread *td)
593{
594 register unsigned int newpriority;
595
596 if (td->td_pri_class == PRI_TIMESHARE) {
597 newpriority = PUSER + td->td_estcpu / INVERSE_ESTCPU_WEIGHT +
598 NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN);
599 newpriority = min(max(newpriority, PRI_MIN_TIMESHARE),
600 PRI_MAX_TIMESHARE);
601 sched_user_prio(td, newpriority);
602 }
603}
604
605/*
606 * Update the thread's priority when the associated process's user
607 * priority changes.
608 */
609static void
610resetpriority_thread(struct thread *td)
611{
612
613 /* Only change threads with a time sharing user priority. */
614 if (td->td_priority < PRI_MIN_TIMESHARE ||
615 td->td_priority > PRI_MAX_TIMESHARE)
616 return;
617
618 /* XXX the whole needresched thing is broken, but not silly. */
619 maybe_resched(td);
620
621 sched_prio(td, td->td_user_pri);
622}
623
624/* ARGSUSED */
625static void
626sched_setup(void *dummy)
627{
628 setup_runqs();
629
630 if (sched_quantum == 0)
631 sched_quantum = SCHED_QUANTUM;
632 hogticks = 2 * sched_quantum;
633
634 /* Account for thread0. */
635 sched_load_add();
636}
637
638/* External interfaces start here */
639
640/*
641 * Very early in the boot some setup of scheduler-specific
642 * parts of proc0 and of some scheduler resources needs to be done.
643 * Called from:
644 * proc0_init()
645 */
646void
647schedinit(void)
648{
649 /*
650 * Set up the scheduler specific parts of proc0.
651 */
652 proc0.p_sched = NULL; /* XXX */
653 thread0.td_sched = &td_sched0;
654 thread0.td_lock = &sched_lock;
655 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
656}
657
658int
659sched_runnable(void)
660{
661#ifdef SMP
662 return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]);
663#else
664 return runq_check(&runq);
665#endif
666}
667
668int
669sched_rr_interval(void)
670{
671 if (sched_quantum == 0)
672 sched_quantum = SCHED_QUANTUM;
673 return (sched_quantum);
674}
675
676/*
677 * We adjust the priority of the current process. The priority of
678 * a process gets worse as it accumulates CPU time. The cpu usage
679 * estimator (td_estcpu) is increased here. resetpriority() will
680 * compute a different priority each time td_estcpu increases by
681 * INVERSE_ESTCPU_WEIGHT
682 * (until MAXPRI is reached). The cpu usage estimator ramps up
683 * quite quickly when the process is running (linearly), and decays
684 * away exponentially, at a rate which is proportionally slower when
685 * the system is busy. The basic principle is that the system will
686 * 90% forget that the process used a lot of CPU time in 5 * loadav
687 * seconds. This causes the system to favor processes which haven't
688 * run much recently, and to round-robin among other processes.
689 */
690void
691sched_clock(struct thread *td)
692{
693 struct pcpuidlestat *stat;
694 struct td_sched *ts;
695
696 THREAD_LOCK_ASSERT(td, MA_OWNED);
697 ts = td->td_sched;
698
699 ts->ts_cpticks++;
700 td->td_estcpu = ESTCPULIM(td->td_estcpu + 1);
701 if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
702 resetpriority(td);
703 resetpriority_thread(td);
704 }
705
706 /*
707 * Force a context switch if the current thread has used up a full
708 * quantum (default quantum is 100ms).
709 */
710 if (!TD_IS_IDLETHREAD(td) &&
711 ticks - PCPU_GET(switchticks) >= sched_quantum)
712 td->td_flags |= TDF_NEEDRESCHED;
713
714 stat = DPCPU_PTR(idlestat);
715 stat->oldidlecalls = stat->idlecalls;
716 stat->idlecalls = 0;
717}
718
719/*
720 * Charge child's scheduling CPU usage to parent.
721 */
722void
723sched_exit(struct proc *p, struct thread *td)
724{
725
726 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit",
727 "prio:td", td->td_priority);
728
729 PROC_LOCK_ASSERT(p, MA_OWNED);
730 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
731}
732
733void
734sched_exit_thread(struct thread *td, struct thread *child)
735{
736
737 KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit",
738 "prio:td", child->td_priority);
739 thread_lock(td);
740 td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu);
741 thread_unlock(td);
742 thread_lock(child);
743 if ((child->td_flags & TDF_NOLOAD) == 0)
744 sched_load_rem();
745 thread_unlock(child);
746}
747
748void
749sched_fork(struct thread *td, struct thread *childtd)
750{
751 sched_fork_thread(td, childtd);
752}
753
754void
755sched_fork_thread(struct thread *td, struct thread *childtd)
756{
757 struct td_sched *ts;
758
759 childtd->td_estcpu = td->td_estcpu;
760 childtd->td_lock = &sched_lock;
761 childtd->td_cpuset = cpuset_ref(td->td_cpuset);
762 ts = childtd->td_sched;
763 bzero(ts, sizeof(*ts));
764 ts->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY);
765}
766
767void
768sched_nice(struct proc *p, int nice)
769{
770 struct thread *td;
771
772 PROC_LOCK_ASSERT(p, MA_OWNED);
773 p->p_nice = nice;
774 FOREACH_THREAD_IN_PROC(p, td) {
775 thread_lock(td);
776 resetpriority(td);
777 resetpriority_thread(td);
778 thread_unlock(td);
779 }
780}
781
782void
783sched_class(struct thread *td, int class)
784{
785 THREAD_LOCK_ASSERT(td, MA_OWNED);
786 td->td_pri_class = class;
787}
788
789/*
790 * Adjust the priority of a thread.
791 */
792static void
793sched_priority(struct thread *td, u_char prio)
794{
795
796
797 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change",
798 "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED,
799 sched_tdname(curthread));
800 if (td != curthread && prio > td->td_priority) {
801 KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
802 "lend prio", "prio:%d", td->td_priority, "new prio:%d",
803 prio, KTR_ATTR_LINKED, sched_tdname(td));
804 }
805 THREAD_LOCK_ASSERT(td, MA_OWNED);
806 if (td->td_priority == prio)
807 return;
808 td->td_priority = prio;
809 if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) {
810 sched_rem(td);
811 sched_add(td, SRQ_BORING);
812 }
813}
814
815/*
816 * Update a thread's priority when it is lent another thread's
817 * priority.
818 */
819void
820sched_lend_prio(struct thread *td, u_char prio)
821{
822
823 td->td_flags |= TDF_BORROWING;
824 sched_priority(td, prio);
825}
826
827/*
828 * Restore a thread's priority when priority propagation is
829 * over. The prio argument is the minimum priority the thread
830 * needs to have to satisfy other possible priority lending
831 * requests. If the thread's regulary priority is less
832 * important than prio the thread will keep a priority boost
833 * of prio.
834 */
835void
836sched_unlend_prio(struct thread *td, u_char prio)
837{
838 u_char base_pri;
839
840 if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
841 td->td_base_pri <= PRI_MAX_TIMESHARE)
842 base_pri = td->td_user_pri;
843 else
844 base_pri = td->td_base_pri;
845 if (prio >= base_pri) {
846 td->td_flags &= ~TDF_BORROWING;
847 sched_prio(td, base_pri);
848 } else
849 sched_lend_prio(td, prio);
850}
851
852void
853sched_prio(struct thread *td, u_char prio)
854{
855 u_char oldprio;
856
857 /* First, update the base priority. */
858 td->td_base_pri = prio;
859
860 /*
861 * If the thread is borrowing another thread's priority, don't ever
862 * lower the priority.
863 */
864 if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
865 return;
866
867 /* Change the real priority. */
868 oldprio = td->td_priority;
869 sched_priority(td, prio);
870
871 /*
872 * If the thread is on a turnstile, then let the turnstile update
873 * its state.
874 */
875 if (TD_ON_LOCK(td) && oldprio != prio)
876 turnstile_adjust(td, oldprio);
877}
878
879void
880sched_user_prio(struct thread *td, u_char prio)
881{
882 u_char oldprio;
883
884 THREAD_LOCK_ASSERT(td, MA_OWNED);
885 td->td_base_user_pri = prio;
886 if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio)
887 return;
888 oldprio = td->td_user_pri;
889 td->td_user_pri = prio;
890}
891
892void
893sched_lend_user_prio(struct thread *td, u_char prio)
894{
895 u_char oldprio;
896
897 THREAD_LOCK_ASSERT(td, MA_OWNED);
898 td->td_flags |= TDF_UBORROWING;
899 oldprio = td->td_user_pri;
900 td->td_user_pri = prio;
901}
902
903void
904sched_unlend_user_prio(struct thread *td, u_char prio)
905{
906 u_char base_pri;
907
908 THREAD_LOCK_ASSERT(td, MA_OWNED);
909 base_pri = td->td_base_user_pri;
910 if (prio >= base_pri) {
911 td->td_flags &= ~TDF_UBORROWING;
912 sched_user_prio(td, base_pri);
913 } else {
914 sched_lend_user_prio(td, prio);
915 }
916}
917
918void
919sched_sleep(struct thread *td, int pri)
920{
921
922 THREAD_LOCK_ASSERT(td, MA_OWNED);
923 td->td_slptick = ticks;
924 td->td_sched->ts_slptime = 0;
925 if (pri)
926 sched_prio(td, pri);
927 if (TD_IS_SUSPENDED(td) || pri >= PSOCK)
928 td->td_flags |= TDF_CANSWAP;
929}
930
931void
932sched_switch(struct thread *td, struct thread *newtd, int flags)
933{
934 struct mtx *tmtx;
935 struct td_sched *ts;
936 struct proc *p;
937
938 tmtx = NULL;
939 ts = td->td_sched;
940 p = td->td_proc;
941
942 THREAD_LOCK_ASSERT(td, MA_OWNED);
943
944 /*
945 * Switch to the sched lock to fix things up and pick
946 * a new thread.
947 * Block the td_lock in order to avoid breaking the critical path.
948 */
949 if (td->td_lock != &sched_lock) {
950 mtx_lock_spin(&sched_lock);
951 tmtx = thread_lock_block(td);
952 }
953
954 if ((td->td_flags & TDF_NOLOAD) == 0)
955 sched_load_rem();
956
957 if (newtd) {
958 MPASS(newtd->td_lock == &sched_lock);
959 newtd->td_flags |= (td->td_flags & TDF_NEEDRESCHED);
960 }
961
962 td->td_lastcpu = td->td_oncpu;
963 td->td_flags &= ~TDF_NEEDRESCHED;
964 td->td_owepreempt = 0;
965 td->td_oncpu = NOCPU;
966
967 /*
968 * At the last moment, if this thread is still marked RUNNING,
969 * then put it back on the run queue as it has not been suspended
970 * or stopped or any thing else similar. We never put the idle
971 * threads on the run queue, however.
972 */
973 if (td->td_flags & TDF_IDLETD) {
974 TD_SET_CAN_RUN(td);
975#ifdef SMP
976 idle_cpus_mask &= ~PCPU_GET(cpumask);
977#endif
978 } else {
979 if (TD_IS_RUNNING(td)) {
980 /* Put us back on the run queue. */
981 sched_add(td, (flags & SW_PREEMPT) ?
982 SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
983 SRQ_OURSELF|SRQ_YIELDING);
984 }
985 }
986 if (newtd) {
987 /*
988 * The thread we are about to run needs to be counted
989 * as if it had been added to the run queue and selected.
990 * It came from:
991 * * A preemption
992 * * An upcall
993 * * A followon
994 */
995 KASSERT((newtd->td_inhibitors == 0),
996 ("trying to run inhibited thread"));
997 newtd->td_flags |= TDF_DIDRUN;
998 TD_SET_RUNNING(newtd);
999 if ((newtd->td_flags & TDF_NOLOAD) == 0)
1000 sched_load_add();
1001 } else {
1002 newtd = choosethread();
1003 MPASS(newtd->td_lock == &sched_lock);
1004 }
1005
1006 if (td != newtd) {
1007#ifdef HWPMC_HOOKS
1008 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1009 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1010#endif
1011 /* I feel sleepy */
1012 lock_profile_release_lock(&sched_lock.lock_object);
1013#ifdef KDTRACE_HOOKS
1014 /*
1015 * If DTrace has set the active vtime enum to anything
1016 * other than INACTIVE (0), then it should have set the
1017 * function to call.
1018 */
1019 if (dtrace_vtime_active)
1020 (*dtrace_vtime_switch_func)(newtd);
1021#endif
1022
1023 cpu_switch(td, newtd, tmtx != NULL ? tmtx : td->td_lock);
1024 lock_profile_obtain_lock_success(&sched_lock.lock_object,
1025 0, 0, __FILE__, __LINE__);
1026 /*
1027 * Where am I? What year is it?
1028 * We are in the same thread that went to sleep above,
1029 * but any amount of time may have passed. All our context
1030 * will still be available as will local variables.
1031 * PCPU values however may have changed as we may have
1032 * changed CPU so don't trust cached values of them.
1033 * New threads will go to fork_exit() instead of here
1034 * so if you change things here you may need to change
1035 * things there too.
1036 *
1037 * If the thread above was exiting it will never wake
1038 * up again here, so either it has saved everything it
1039 * needed to, or the thread_wait() or wait() will
1040 * need to reap it.
1041 */
1042#ifdef HWPMC_HOOKS
1043 if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1044 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
1045#endif
1046 }
1047
1048#ifdef SMP
1049 if (td->td_flags & TDF_IDLETD)
1050 idle_cpus_mask |= PCPU_GET(cpumask);
1051#endif
1052 sched_lock.mtx_lock = (uintptr_t)td;
1053 td->td_oncpu = PCPU_GET(cpuid);
1054 MPASS(td->td_lock == &sched_lock);
1055}
1056
1057void
1058sched_wakeup(struct thread *td)
1059{
1060 struct td_sched *ts;
1061
1062 THREAD_LOCK_ASSERT(td, MA_OWNED);
1063 ts = td->td_sched;
1064 td->td_flags &= ~TDF_CANSWAP;
1065 if (ts->ts_slptime > 1) {
1066 updatepri(td);
1067 resetpriority(td);
1068 }
1069 td->td_slptick = 0;
1070 ts->ts_slptime = 0;
1071 sched_add(td, SRQ_BORING);
1072}
1073
1074#ifdef SMP
1075static int
1076forward_wakeup(int cpunum)
1077{
1078 struct pcpu *pc;
1079 cpumask_t dontuse, id, map, map2, map3, me;
1080
1081 mtx_assert(&sched_lock, MA_OWNED);
1082
1083 CTR0(KTR_RUNQ, "forward_wakeup()");
1084
1085 if ((!forward_wakeup_enabled) ||
1086 (forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0))
1087 return (0);
1088 if (!smp_started || cold || panicstr)
1089 return (0);
1090
1091 forward_wakeups_requested++;
1092
1093 /*
1094 * Check the idle mask we received against what we calculated
1095 * before in the old version.
1096 */
1097 me = PCPU_GET(cpumask);
1098
1099 /* Don't bother if we should be doing it ourself. */
1100 if ((me & idle_cpus_mask) && (cpunum == NOCPU || me == (1 << cpunum)))
1101 return (0);
1102
1103 dontuse = me | stopped_cpus | hlt_cpus_mask;
1104 map3 = 0;
1105 if (forward_wakeup_use_loop) {
1106 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
1107 id = pc->pc_cpumask;
1108 if ((id & dontuse) == 0 &&
1109 pc->pc_curthread == pc->pc_idlethread) {
1110 map3 |= id;
1111 }
1112 }
1113 }
1114
1115 if (forward_wakeup_use_mask) {
1116 map = 0;
1117 map = idle_cpus_mask & ~dontuse;
1118
1119 /* If they are both on, compare and use loop if different. */
1120 if (forward_wakeup_use_loop) {
1121 if (map != map3) {
1122 printf("map (%02X) != map3 (%02X)\n", map,
1123 map3);
1124 map = map3;
1125 }
1126 }
1127 } else {
1128 map = map3;
1129 }
1130
1131 /* If we only allow a specific CPU, then mask off all the others. */
1132 if (cpunum != NOCPU) {
1133 KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum."));
1134 map &= (1 << cpunum);
1135 } else {
1136 /* Try choose an idle die. */
1137 if (forward_wakeup_use_htt) {
1138 map2 = (map & (map >> 1)) & 0x5555;
1139 if (map2) {
1140 map = map2;
1141 }
1142 }
1143
1144 /* Set only one bit. */
1145 if (forward_wakeup_use_single) {
1146 map = map & ((~map) + 1);
1147 }
1148 }
1149 if (map) {
1150 forward_wakeups_delivered++;
1151 SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
1152 id = pc->pc_cpumask;
1153 if ((map & id) == 0)
1154 continue;
1155 if (cpu_idle_wakeup(pc->pc_cpuid))
1156 map &= ~id;
1157 }
1158 if (map)
1159 ipi_selected(map, IPI_AST);
1160 return (1);
1161 }
1162 if (cpunum == NOCPU)
1163 printf("forward_wakeup: Idle processor not found\n");
1164 return (0);
1165}
1166
1167static void
1168kick_other_cpu(int pri, int cpuid)
1169{
1170 struct pcpu *pcpu;
1171 int cpri;
1172
1173 pcpu = pcpu_find(cpuid);
1174 if (idle_cpus_mask & pcpu->pc_cpumask) {
1175 forward_wakeups_delivered++;
1176 if (!cpu_idle_wakeup(cpuid))
1177 ipi_cpu(cpuid, IPI_AST);
1178 return;
1179 }
1180
1181 cpri = pcpu->pc_curthread->td_priority;
1182 if (pri >= cpri)
1183 return;
1184
1185#if defined(IPI_PREEMPTION) && defined(PREEMPTION)
1186#if !defined(FULL_PREEMPTION)
1187 if (pri <= PRI_MAX_ITHD)
1188#endif /* ! FULL_PREEMPTION */
1189 {
1190 ipi_cpu(cpuid, IPI_PREEMPT);
1191 return;
1192 }
1193#endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */
1194
1195 pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED;
1196 ipi_cpu(cpuid, IPI_AST);
1197 return;
1198}
1199#endif /* SMP */
1200
1201#ifdef SMP
1202static int
1203sched_pickcpu(struct thread *td)
1204{
1205 int best, cpu;
1206
1207 mtx_assert(&sched_lock, MA_OWNED);
1208
1209 if (THREAD_CAN_SCHED(td, td->td_lastcpu))
1210 best = td->td_lastcpu;
1211 else
1212 best = NOCPU;
1213 CPU_FOREACH(cpu) {
1214 if (!THREAD_CAN_SCHED(td, cpu))
1215 continue;
1216
1217 if (best == NOCPU)
1218 best = cpu;
1219 else if (runq_length[cpu] < runq_length[best])
1220 best = cpu;
1221 }
1222 KASSERT(best != NOCPU, ("no valid CPUs"));
1223
1224 return (best);
1225}
1226#endif
1227
1228void
1229sched_add(struct thread *td, int flags)
1230#ifdef SMP
1231{
1232 struct td_sched *ts;
1233 int forwarded = 0;
1234 int cpu;
1235 int single_cpu = 0;
1236
1237 ts = td->td_sched;
1238 THREAD_LOCK_ASSERT(td, MA_OWNED);
1239 KASSERT((td->td_inhibitors == 0),
1240 ("sched_add: trying to run inhibited thread"));
1241 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
1242 ("sched_add: bad thread state"));
1243 KASSERT(td->td_flags & TDF_INMEM,
1244 ("sched_add: thread swapped out"));
1245
1246 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
1247 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1248 sched_tdname(curthread));
1249 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
1250 KTR_ATTR_LINKED, sched_tdname(td));
1251
1252
1253 /*
1254 * Now that the thread is moving to the run-queue, set the lock
1255 * to the scheduler's lock.
1256 */
1257 if (td->td_lock != &sched_lock) {
1258 mtx_lock_spin(&sched_lock);
1259 thread_lock_set(td, &sched_lock);
1260 }
1261 TD_SET_RUNQ(td);
1262
1263 if (td->td_pinned != 0) {
1264 cpu = td->td_lastcpu;
1265 ts->ts_runq = &runq_pcpu[cpu];
1266 single_cpu = 1;
1267 CTR3(KTR_RUNQ,
1268 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
1269 cpu);
1270 } else if (td->td_flags & TDF_BOUND) {
1271 /* Find CPU from bound runq. */
1272 KASSERT(SKE_RUNQ_PCPU(ts),
1273 ("sched_add: bound td_sched not on cpu runq"));
1274 cpu = ts->ts_runq - &runq_pcpu[0];
1275 single_cpu = 1;
1276 CTR3(KTR_RUNQ,
1277 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
1278 cpu);
1279 } else if (ts->ts_flags & TSF_AFFINITY) {
1280 /* Find a valid CPU for our cpuset */
1281 cpu = sched_pickcpu(td);
1282 ts->ts_runq = &runq_pcpu[cpu];
1283 single_cpu = 1;
1284 CTR3(KTR_RUNQ,
1285 "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
1286 cpu);
1287 } else {
1288 CTR2(KTR_RUNQ,
1289 "sched_add: adding td_sched:%p (td:%p) to gbl runq", ts,
1290 td);
1291 cpu = NOCPU;
1292 ts->ts_runq = &runq;
1293 }
1294
1295 if (single_cpu && (cpu != PCPU_GET(cpuid))) {
1296 kick_other_cpu(td->td_priority, cpu);
1297 } else {
1298 if (!single_cpu) {
1299 cpumask_t me = PCPU_GET(cpumask);
1300 cpumask_t idle = idle_cpus_mask & me;
1301
1302 if (!idle && ((flags & SRQ_INTR) == 0) &&
1303 (idle_cpus_mask & ~(hlt_cpus_mask | me)))
1304 forwarded = forward_wakeup(cpu);
1305 }
1306
1307 if (!forwarded) {
1308 if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td))
1309 return;
1310 else
1311 maybe_resched(td);
1312 }
1313 }
1314
1315 if ((td->td_flags & TDF_NOLOAD) == 0)
1316 sched_load_add();
1317 runq_add(ts->ts_runq, td, flags);
1318 if (cpu != NOCPU)
1319 runq_length[cpu]++;
1320}
1321#else /* SMP */
1322{
1323 struct td_sched *ts;
1324
1325 ts = td->td_sched;
1326 THREAD_LOCK_ASSERT(td, MA_OWNED);
1327 KASSERT((td->td_inhibitors == 0),
1328 ("sched_add: trying to run inhibited thread"));
1329 KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
1330 ("sched_add: bad thread state"));
1331 KASSERT(td->td_flags & TDF_INMEM,
1332 ("sched_add: thread swapped out"));
1333 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
1334 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1335 sched_tdname(curthread));
1336 KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
1337 KTR_ATTR_LINKED, sched_tdname(td));
1338
1339 /*
1340 * Now that the thread is moving to the run-queue, set the lock
1341 * to the scheduler's lock.
1342 */
1343 if (td->td_lock != &sched_lock) {
1344 mtx_lock_spin(&sched_lock);
1345 thread_lock_set(td, &sched_lock);
1346 }
1347 TD_SET_RUNQ(td);
1348 CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td);
1349 ts->ts_runq = &runq;
1350
1351 /*
1352 * If we are yielding (on the way out anyhow) or the thread
1353 * being saved is US, then don't try be smart about preemption
1354 * or kicking off another CPU as it won't help and may hinder.
1355 * In the YIEDLING case, we are about to run whoever is being
1356 * put in the queue anyhow, and in the OURSELF case, we are
1357 * puting ourself on the run queue which also only happens
1358 * when we are about to yield.
1359 */
1360 if ((flags & SRQ_YIELDING) == 0) {
1361 if (maybe_preempt(td))
1362 return;
1363 }
1364 if ((td->td_flags & TDF_NOLOAD) == 0)
1365 sched_load_add();
1366 runq_add(ts->ts_runq, td, flags);
1367 maybe_resched(td);
1368}
1369#endif /* SMP */
1370
1371void
1372sched_rem(struct thread *td)
1373{
1374 struct td_sched *ts;
1375
1376 ts = td->td_sched;
1377 KASSERT(td->td_flags & TDF_INMEM,
1378 ("sched_rem: thread swapped out"));
1379 KASSERT(TD_ON_RUNQ(td),
1380 ("sched_rem: thread not on run queue"));
1381 mtx_assert(&sched_lock, MA_OWNED);
1382 KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
1383 "prio:%d", td->td_priority, KTR_ATTR_LINKED,
1384 sched_tdname(curthread));
1385
1386 if ((td->td_flags & TDF_NOLOAD) == 0)
1387 sched_load_rem();
1388#ifdef SMP
1389 if (ts->ts_runq != &runq)
1390 runq_length[ts->ts_runq - runq_pcpu]--;
1391#endif
1392 runq_remove(ts->ts_runq, td);
1393 TD_SET_CAN_RUN(td);
1394}
1395
1396/*
1397 * Select threads to run. Note that running threads still consume a
1398 * slot.
1399 */
1400struct thread *
1401sched_choose(void)
1402{
1403 struct thread *td;
1404 struct runq *rq;
1405
1406 mtx_assert(&sched_lock, MA_OWNED);
1407#ifdef SMP
1408 struct thread *tdcpu;
1409
1410 rq = &runq;
1411 td = runq_choose_fuzz(&runq, runq_fuzz);
1412 tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]);
1413
1414 if (td == NULL ||
1415 (tdcpu != NULL &&
1416 tdcpu->td_priority < td->td_priority)) {
1417 CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu,
1418 PCPU_GET(cpuid));
1419 td = tdcpu;
1420 rq = &runq_pcpu[PCPU_GET(cpuid)];
1421 } else {
1422 CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td);
1423 }
1424
1425#else
1426 rq = &runq;
1427 td = runq_choose(&runq);
1428#endif
1429
1430 if (td) {
1431#ifdef SMP
1432 if (td == tdcpu)
1433 runq_length[PCPU_GET(cpuid)]--;
1434#endif
1435 runq_remove(rq, td);
1436 td->td_flags |= TDF_DIDRUN;
1437
1438 KASSERT(td->td_flags & TDF_INMEM,
1439 ("sched_choose: thread swapped out"));
1440 return (td);
1441 }
1442 return (PCPU_GET(idlethread));
1443}
1444
1445void
1446sched_preempt(struct thread *td)
1447{
1448 thread_lock(td);
1449 if (td->td_critnest > 1)
1450 td->td_owepreempt = 1;
1451 else
1452 mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, NULL);
1453 thread_unlock(td);
1454}
1455
1456void
1457sched_userret(struct thread *td)
1458{
1459 /*
1460 * XXX we cheat slightly on the locking here to avoid locking in
1461 * the usual case. Setting td_priority here is essentially an
1462 * incomplete workaround for not setting it properly elsewhere.
1463 * Now that some interrupt handlers are threads, not setting it
1464 * properly elsewhere can clobber it in the window between setting
1465 * it here and returning to user mode, so don't waste time setting
1466 * it perfectly here.
1467 */
1468 KASSERT((td->td_flags & TDF_BORROWING) == 0,
1469 ("thread with borrowed priority returning to userland"));
1470 if (td->td_priority != td->td_user_pri) {
1471 thread_lock(td);
1472 td->td_priority = td->td_user_pri;
1473 td->td_base_pri = td->td_user_pri;
1474 thread_unlock(td);
1475 }
1476}
1477
1478void
1479sched_bind(struct thread *td, int cpu)
1480{
1481 struct td_sched *ts;
1482
1483 THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
1484 KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
1485
1486 ts = td->td_sched;
1487
1488 td->td_flags |= TDF_BOUND;
1489#ifdef SMP
1490 ts->ts_runq = &runq_pcpu[cpu];
1491 if (PCPU_GET(cpuid) == cpu)
1492 return;
1493
1494 mi_switch(SW_VOL, NULL);
1495#endif
1496}
1497
1498void
1499sched_unbind(struct thread* td)
1500{
1501 THREAD_LOCK_ASSERT(td, MA_OWNED);
1502 KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
1503 td->td_flags &= ~TDF_BOUND;
1504}
1505
1506int
1507sched_is_bound(struct thread *td)
1508{
1509 THREAD_LOCK_ASSERT(td, MA_OWNED);
1510 return (td->td_flags & TDF_BOUND);
1511}
1512
1513void
1514sched_relinquish(struct thread *td)
1515{
1516 thread_lock(td);
1517 mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
1518 thread_unlock(td);
1519}
1520
1521int
1522sched_load(void)
1523{
1524 return (sched_tdcnt);
1525}
1526
1527int
1528sched_sizeof_proc(void)
1529{
1530 return (sizeof(struct proc));
1531}
1532
1533int
1534sched_sizeof_thread(void)
1535{
1536 return (sizeof(struct thread) + sizeof(struct td_sched));
1537}
1538
1539fixpt_t
1540sched_pctcpu(struct thread *td)
1541{
1542 struct td_sched *ts;
1543
1544 THREAD_LOCK_ASSERT(td, MA_OWNED);
1545 ts = td->td_sched;
1546 return (ts->ts_pctcpu);
1547}
1548
1549void
1550sched_tick(int cnt)
1551{
1552}
1553
1554/*
1555 * The actual idle process.
1556 */
1557void
1558sched_idletd(void *dummy)
1559{
1560 struct pcpuidlestat *stat;
1561
1562 stat = DPCPU_PTR(idlestat);
1563 for (;;) {
1564 mtx_assert(&Giant, MA_NOTOWNED);
1565
1566 while (sched_runnable() == 0) {
1567 cpu_idle(stat->idlecalls + stat->oldidlecalls > 64);
1568 stat->idlecalls++;
1569 }
1570
1571 mtx_lock_spin(&sched_lock);
1572 mi_switch(SW_VOL | SWT_IDLE, NULL);
1573 mtx_unlock_spin(&sched_lock);
1574 }
1575}
1576
1577/*
1578 * A CPU is entering for the first time or a thread is exiting.
1579 */
1580void
1581sched_throw(struct thread *td)
1582{
1583 /*
1584 * Correct spinlock nesting. The idle thread context that we are
1585 * borrowing was created so that it would start out with a single
1586 * spin lock (sched_lock) held in fork_trampoline(). Since we've
1587 * explicitly acquired locks in this function, the nesting count
1588 * is now 2 rather than 1. Since we are nested, calling
1589 * spinlock_exit() will simply adjust the counts without allowing
1590 * spin lock using code to interrupt us.
1591 */
1592 if (td == NULL) {
1593 mtx_lock_spin(&sched_lock);
1594 spinlock_exit();
1595 } else {
1596 lock_profile_release_lock(&sched_lock.lock_object);
1597 MPASS(td->td_lock == &sched_lock);
1598 }
1599 mtx_assert(&sched_lock, MA_OWNED);
1600 KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
1601 PCPU_SET(switchtime, cpu_ticks());
1602 PCPU_SET(switchticks, ticks);
1603 cpu_throw(td, choosethread()); /* doesn't return */
1604}
1605
1606void
1607sched_fork_exit(struct thread *td)
1608{
1609
1610 /*
1611 * Finish setting up thread glue so that it begins execution in a
1612 * non-nested critical section with sched_lock held but not recursed.
1613 */
1614 td->td_oncpu = PCPU_GET(cpuid);
1615 sched_lock.mtx_lock = (uintptr_t)td;
1616 lock_profile_obtain_lock_success(&sched_lock.lock_object,
1617 0, 0, __FILE__, __LINE__);
1618 THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
1619}
1620
1621char *
1622sched_tdname(struct thread *td)
1623{
1624#ifdef KTR
1625 struct td_sched *ts;
1626
1627 ts = td->td_sched;
1628 if (ts->ts_name[0] == '\0')
1629 snprintf(ts->ts_name, sizeof(ts->ts_name),
1630 "%s tid %d", td->td_name, td->td_tid);
1631 return (ts->ts_name);
1632#else
1633 return (td->td_name);
1634#endif
1635}
1636
1637void
1638sched_affinity(struct thread *td)
1639{
1640#ifdef SMP
1641 struct td_sched *ts;
1642 int cpu;
1643
1644 THREAD_LOCK_ASSERT(td, MA_OWNED);
1645
1646 /*
1647 * Set the TSF_AFFINITY flag if there is at least one CPU this
1648 * thread can't run on.
1649 */
1650 ts = td->td_sched;
1651 ts->ts_flags &= ~TSF_AFFINITY;
1652 CPU_FOREACH(cpu) {
1653 if (!THREAD_CAN_SCHED(td, cpu)) {
1654 ts->ts_flags |= TSF_AFFINITY;
1655 break;
1656 }
1657 }
1658
1659 /*
1660 * If this thread can run on all CPUs, nothing else to do.
1661 */
1662 if (!(ts->ts_flags & TSF_AFFINITY))
1663 return;
1664
1665 /* Pinned threads and bound threads should be left alone. */
1666 if (td->td_pinned != 0 || td->td_flags & TDF_BOUND)
1667 return;
1668
1669 switch (td->td_state) {
1670 case TDS_RUNQ:
1671 /*
1672 * If we are on a per-CPU runqueue that is in the set,
1673 * then nothing needs to be done.
1674 */
1675 if (ts->ts_runq != &runq &&
1676 THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu))
1677 return;
1678
1679 /* Put this thread on a valid per-CPU runqueue. */
1680 sched_rem(td);
1681 sched_add(td, SRQ_BORING);
1682 break;
1683 case TDS_RUNNING:
1684 /*
1685 * See if our current CPU is in the set. If not, force a
1686 * context switch.
1687 */
1688 if (THREAD_CAN_SCHED(td, td->td_oncpu))
1689 return;
1690
1691 td->td_flags |= TDF_NEEDRESCHED;
1692 if (td != curthread)
1693 ipi_cpu(cpu, IPI_AST);
1694 break;
1695 default:
1696 break;
1697 }
1698#endif
1699}
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