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38 * @(#)kern_synch.c 8.9 (Berkeley) 5/19/95
39 * $FreeBSD: src/sys/kern/kern_synch.c,v 1.87.2.6 2002/10/13 07:29:53 kbyanc Exp $
40 * $DragonFly: src/sys/kern/kern_synch.c,v 1.84 2007/05/01 00:05:18 dillon Exp $
43 #include "opt_ktrace.h"
45 #include <sys/param.h>
46 #include <sys/systm.h>
48 #include <sys/kernel.h>
49 #include <sys/signalvar.h>
50 #include <sys/signal2.h>
51 #include <sys/resourcevar.h>
52 #include <sys/vmmeter.h>
53 #include <sys/sysctl.h>
57 #include <sys/ktrace.h>
59 #include <sys/xwait.h>
62 #include <sys/thread2.h>
63 #include <sys/spinlock2.h>
65 #include <machine/cpu.h>
66 #include <machine/smp.h>
68 TAILQ_HEAD(tslpque, thread);
70 static void sched_setup (void *dummy);
71 SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL)
76 int sched_quantum; /* Roundrobin scheduling quantum in ticks. */
78 int ncpus2, ncpus2_shift, ncpus2_mask;
79 int ncpus_fit, ncpus_fit_mask;
83 static struct callout loadav_callout;
84 static struct callout schedcpu_callout;
85 MALLOC_DEFINE(M_TSLEEP, "tslpque", "tsleep queues");
87 #if !defined(KTR_TSLEEP)
88 #define KTR_TSLEEP KTR_ALL
90 KTR_INFO_MASTER(tsleep);
91 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_beg, 0, "tsleep enter", 0);
92 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_end, 0, "tsleep exit", 0);
93 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_beg, 0, "wakeup enter", 0);
94 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_end, 0, "wakeup exit", 0);
95 #define logtsleep(name) KTR_LOG(tsleep_ ## name)
97 struct loadavg averunnable =
98 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */
100 * Constants for averages over 1, 5, and 15 minutes
101 * when sampling at 5 second intervals.
103 static fixpt_t cexp[3] = {
104 0.9200444146293232 * FSCALE, /* exp(-1/12) */
105 0.9834714538216174 * FSCALE, /* exp(-1/60) */
106 0.9944598480048967 * FSCALE, /* exp(-1/180) */
109 static void endtsleep (void *);
110 static void unsleep_and_wakeup_thread(struct thread *td);
111 static void loadav (void *arg);
112 static void schedcpu (void *arg);
115 * Adjust the scheduler quantum. The quantum is specified in microseconds.
116 * Note that 'tick' is in microseconds per tick.
119 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
123 new_val = sched_quantum * tick;
124 error = sysctl_handle_int(oidp, &new_val, 0, req);
125 if (error != 0 || req->newptr == NULL)
129 sched_quantum = new_val / tick;
130 hogticks = 2 * sched_quantum;
134 SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW,
135 0, sizeof sched_quantum, sysctl_kern_quantum, "I", "");
138 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
139 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
140 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
142 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
143 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
145 * If you don't want to bother with the faster/more-accurate formula, you
146 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
147 * (more general) method of calculating the %age of CPU used by a process.
149 * decay 95% of `lwp_pctcpu' in 60 seconds; see CCPU_SHIFT before changing
151 #define CCPU_SHIFT 11
153 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
154 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
157 * kernel uses `FSCALE', userland (SHOULD) use kern.fscale
159 int fscale __unused = FSCALE; /* exported to systat */
160 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, "");
163 * Recompute process priorities, once a second.
165 * Since the userland schedulers are typically event oriented, if the
166 * estcpu calculation at wakeup() time is not sufficient to make a
167 * process runnable relative to other processes in the system we have
168 * a 1-second recalc to help out.
170 * This code also allows us to store sysclock_t data in the process structure
171 * without fear of an overrun, since sysclock_t are guarenteed to hold
172 * several seconds worth of count.
174 * WARNING! callouts can preempt normal threads. However, they will not
175 * preempt a thread holding a spinlock so we *can* safely use spinlocks.
177 static int schedcpu_stats(struct proc *p, void *data __unused);
178 static int schedcpu_resource(struct proc *p, void *data __unused);
183 allproc_scan(schedcpu_stats, NULL);
184 allproc_scan(schedcpu_resource, NULL);
185 wakeup((caddr_t)&lbolt);
186 wakeup((caddr_t)&lbolt_syncer);
187 callout_reset(&schedcpu_callout, hz, schedcpu, NULL);
191 * General process statistics once a second
194 schedcpu_stats(struct proc *p, void *data __unused)
200 FOREACH_LWP_IN_PROC(lp, p) {
201 if (lp->lwp_stat == LSSLEEP)
205 * Only recalculate processes that are active or have slept
206 * less then 2 seconds. The schedulers understand this.
208 if (lp->lwp_slptime <= 1) {
209 p->p_usched->recalculate(lp);
211 lp->lwp_pctcpu = (lp->lwp_pctcpu * ccpu) >> FSHIFT;
219 * Resource checks. XXX break out since ksignal/killproc can block,
220 * limiting us to one process killed per second. There is probably
224 schedcpu_resource(struct proc *p, void *data __unused)
230 if (p->p_stat == SIDL ||
231 p->p_stat == SZOMB ||
239 FOREACH_LWP_IN_PROC(lp, p) {
240 ttime += lp->lwp_thread->td_sticks;
241 ttime += lp->lwp_thread->td_uticks;
244 switch(plimit_testcpulimit(p->p_limit, ttime)) {
245 case PLIMIT_TESTCPU_KILL:
246 killproc(p, "exceeded maximum CPU limit");
248 case PLIMIT_TESTCPU_XCPU:
249 if ((p->p_flag & P_XCPU) == 0) {
262 * This is only used by ps. Generate a cpu percentage use over
263 * a period of one second.
268 updatepcpu(struct lwp *lp, int cpticks, int ttlticks)
273 acc = (cpticks << FSHIFT) / ttlticks;
274 if (ttlticks >= ESTCPUFREQ) {
275 lp->lwp_pctcpu = acc;
277 remticks = ESTCPUFREQ - ttlticks;
278 lp->lwp_pctcpu = (acc * ttlticks + lp->lwp_pctcpu * remticks) /
284 * We're only looking at 7 bits of the address; everything is
285 * aligned to 4, lots of things are aligned to greater powers
286 * of 2. Shift right by 8, i.e. drop the bottom 256 worth.
288 #define TABLESIZE 128
289 #define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1))
291 static cpumask_t slpque_cpumasks[TABLESIZE];
294 * General scheduler initialization. We force a reschedule 25 times
295 * a second by default. Note that cpu0 is initialized in early boot and
296 * cannot make any high level calls.
298 * Each cpu has its own sleep queue.
301 sleep_gdinit(globaldata_t gd)
303 static struct tslpque slpque_cpu0[TABLESIZE];
306 if (gd->gd_cpuid == 0) {
307 sched_quantum = (hz + 24) / 25;
308 hogticks = 2 * sched_quantum;
310 gd->gd_tsleep_hash = slpque_cpu0;
312 gd->gd_tsleep_hash = kmalloc(sizeof(slpque_cpu0),
313 M_TSLEEP, M_WAITOK | M_ZERO);
315 for (i = 0; i < TABLESIZE; ++i)
316 TAILQ_INIT(&gd->gd_tsleep_hash[i]);
320 * General sleep call. Suspends the current process until a wakeup is
321 * performed on the specified identifier. The process will then be made
322 * runnable with the specified priority. Sleeps at most timo/hz seconds
323 * (0 means no timeout). If flags includes PCATCH flag, signals are checked
324 * before and after sleeping, else signals are not checked. Returns 0 if
325 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a
326 * signal needs to be delivered, ERESTART is returned if the current system
327 * call should be restarted if possible, and EINTR is returned if the system
328 * call should be interrupted by the signal (return EINTR).
330 * Note that if we are a process, we release_curproc() before messing with
331 * the LWKT scheduler.
333 * During autoconfiguration or after a panic, a sleep will simply
334 * lower the priority briefly to allow interrupts, then return.
337 tsleep(void *ident, int flags, const char *wmesg, int timo)
339 struct thread *td = curthread;
340 struct lwp *lp = td->td_lwp;
341 struct proc *p = td->td_proc; /* may be NULL */
348 struct callout thandle;
351 * NOTE: removed KTRPOINT, it could cause races due to blocking
352 * even in stable. Just scrap it for now.
354 if (tsleep_now_works == 0 || panicstr) {
356 * After a panic, or before we actually have an operational
357 * softclock, just give interrupts a chance, then just return;
359 * don't run any other procs or panic below,
360 * in case this is the idle process and already asleep.
363 oldpri = td->td_pri & TDPRI_MASK;
364 lwkt_setpri_self(safepri);
366 lwkt_setpri_self(oldpri);
369 logtsleep(tsleep_beg);
371 KKASSERT(td != &gd->gd_idlethread); /* you must be kidding! */
374 * NOTE: all of this occurs on the current cpu, including any
375 * callout-based wakeups, so a critical section is a sufficient
378 * The entire sequence through to where we actually sleep must
379 * run without breaking the critical section.
382 catch = flags & PCATCH;
386 crit_enter_quick(td);
388 KASSERT(ident != NULL, ("tsleep: no ident"));
389 KASSERT(lp == NULL ||
390 lp->lwp_stat == LSRUN || /* Obvious */
391 lp->lwp_stat == LSSTOP, /* Set in tstop */
393 ident, wmesg, lp->lwp_stat));
396 * Setup for the current process (if this is a process).
401 * Early termination if PCATCH was set and a
402 * signal is pending, interlocked with the
405 * Early termination only occurs when tsleep() is
406 * entered while in a normal LSRUN state.
408 if ((sig = CURSIG(lp)) != 0)
412 * Early termination if PCATCH was set and a
413 * mailbox signal was possibly delivered prior to
414 * the system call even being made, in order to
415 * allow the user to interlock without having to
416 * make additional system calls.
418 if (p->p_flag & P_MAILBOX)
422 * Causes ksignal to wake us up when.
424 lp->lwp_flag |= LWP_SINTR;
428 * Make sure the current process has been untangled from
429 * the userland scheduler and initialize slptime to start
432 if (flags & PNORESCHED)
433 td->td_flags |= TDF_NORESCHED;
434 p->p_usched->release_curproc(lp);
439 * Move our thread to the correct queue and setup our wchan, etc.
441 lwkt_deschedule_self(td);
442 td->td_flags |= TDF_TSLEEPQ;
443 TAILQ_INSERT_TAIL(&gd->gd_tsleep_hash[id], td, td_threadq);
444 atomic_set_int(&slpque_cpumasks[id], gd->gd_cpumask);
446 td->td_wchan = ident;
447 td->td_wmesg = wmesg;
448 td->td_wdomain = flags & PDOMAIN_MASK;
451 * Setup the timeout, if any
454 callout_init(&thandle);
455 callout_reset(&thandle, timo, endtsleep, td);
463 * Ok, we are sleeping. Place us in the SSLEEP state.
465 KKASSERT((lp->lwp_flag & LWP_ONRUNQ) == 0);
467 * tstop() sets LSSTOP, so don't fiddle with that.
469 if (lp->lwp_stat != LSSTOP)
470 lp->lwp_stat = LSSLEEP;
471 lp->lwp_ru.ru_nvcsw++;
475 * And when we are woken up, put us back in LSRUN. If we
476 * slept for over a second, recalculate our estcpu.
478 lp->lwp_stat = LSRUN;
480 p->p_usched->recalculate(lp);
487 * Make sure we haven't switched cpus while we were asleep. It's
488 * not supposed to happen. Cleanup our temporary flags.
490 KKASSERT(gd == td->td_gd);
491 td->td_flags &= ~TDF_NORESCHED;
494 * Cleanup the timeout.
497 if (td->td_flags & TDF_TIMEOUT) {
498 td->td_flags &= ~TDF_TIMEOUT;
501 callout_stop(&thandle);
506 * Since td_threadq is used both for our run queue AND for the
507 * tsleep hash queue, we can't still be on it at this point because
508 * we've gotten cpu back.
510 KASSERT((td->td_flags & TDF_TSLEEPQ) == 0, ("tsleep: impossible thread flags %08x", td->td_flags));
516 * Figure out the correct error return. If interrupted by a
517 * signal we want to return EINTR or ERESTART.
519 * If P_MAILBOX is set no automatic system call restart occurs
520 * and we return EINTR. P_MAILBOX is meant to be used as an
521 * interlock, the user must poll it prior to any system call
522 * that it wishes to interlock a mailbox signal against since
523 * the flag is cleared on *any* system call that sleeps.
527 if (catch && error == 0) {
528 if ((p->p_flag & P_MAILBOX) && sig == 0) {
530 } else if (sig != 0 || (sig = CURSIG(lp))) {
531 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
537 lp->lwp_flag &= ~(LWP_BREAKTSLEEP | LWP_SINTR);
538 p->p_flag &= ~P_MAILBOX;
540 logtsleep(tsleep_end);
546 * This is a dandy function that allows us to interlock tsleep/wakeup
547 * operations with unspecified upper level locks, such as lockmgr locks,
548 * simply by holding a critical section. The sequence is:
550 * (enter critical section)
551 * (acquire upper level lock)
552 * tsleep_interlock(blah)
553 * (release upper level lock)
555 * (exit critical section)
557 * Basically this function sets our cpumask for the ident which informs
558 * other cpus that our cpu 'might' be waiting (or about to wait on) the
559 * hash index related to the ident. The critical section prevents another
560 * cpu's wakeup() from being processed on our cpu until we are actually
561 * able to enter the tsleep(). Thus, no race occurs between our attempt
562 * to release a resource and sleep, and another cpu's attempt to acquire
563 * a resource and call wakeup.
565 * There isn't much of a point to this function unless you call it while
566 * holding a critical section.
569 _tsleep_interlock(globaldata_t gd, void *ident)
571 int id = LOOKUP(ident);
573 atomic_set_int(&slpque_cpumasks[id], gd->gd_cpumask);
577 tsleep_interlock(void *ident)
579 _tsleep_interlock(mycpu, ident);
583 * Interlocked spinlock sleep. An exclusively held spinlock must
584 * be passed to msleep(). The function will atomically release the
585 * spinlock and tsleep on the ident, then reacquire the spinlock and
588 * This routine is fairly important along the critical path, so optimize it
592 msleep(void *ident, struct spinlock *spin, int flags,
593 const char *wmesg, int timo)
595 globaldata_t gd = mycpu;
599 _tsleep_interlock(gd, ident);
600 spin_unlock_wr_quick(gd, spin);
601 error = tsleep(ident, flags, wmesg, timo);
602 spin_lock_wr_quick(gd, spin);
609 * Implement the timeout for tsleep.
611 * We set LWP_BREAKTSLEEP to indicate that an event has occured, but
612 * we only call setrunnable if the process is not stopped.
614 * This type of callout timeout is scheduled on the same cpu the process
615 * is sleeping on. Also, at the moment, the MP lock is held.
623 ASSERT_MP_LOCK_HELD(curthread);
627 * cpu interlock. Thread flags are only manipulated on
628 * the cpu owning the thread. proc flags are only manipulated
629 * by the older of the MP lock. We have both.
631 if (td->td_flags & TDF_TSLEEPQ) {
632 td->td_flags |= TDF_TIMEOUT;
634 if ((lp = td->td_lwp) != NULL) {
635 lp->lwp_flag |= LWP_BREAKTSLEEP;
636 if (lp->lwp_proc->p_stat != SSTOP)
639 unsleep_and_wakeup_thread(td);
646 * Unsleep and wakeup a thread. This function runs without the MP lock
647 * which means that it can only manipulate thread state on the owning cpu,
648 * and cannot touch the process state at all.
652 unsleep_and_wakeup_thread(struct thread *td)
654 globaldata_t gd = mycpu;
658 if (td->td_gd != gd) {
659 lwkt_send_ipiq(td->td_gd, (ipifunc1_t)unsleep_and_wakeup_thread, td);
664 if (td->td_flags & TDF_TSLEEPQ) {
665 td->td_flags &= ~TDF_TSLEEPQ;
666 id = LOOKUP(td->td_wchan);
667 TAILQ_REMOVE(&gd->gd_tsleep_hash[id], td, td_threadq);
668 if (TAILQ_FIRST(&gd->gd_tsleep_hash[id]) == NULL)
669 atomic_clear_int(&slpque_cpumasks[id], gd->gd_cpumask);
676 * Make all processes sleeping on the specified identifier runnable.
677 * count may be zero or one only.
679 * The domain encodes the sleep/wakeup domain AND the first cpu to check
680 * (which is always the current cpu). As we iterate across cpus
682 * This call may run without the MP lock held. We can only manipulate thread
683 * state on the cpu owning the thread. We CANNOT manipulate process state
687 _wakeup(void *ident, int domain)
702 logtsleep(wakeup_beg);
705 qp = &gd->gd_tsleep_hash[id];
707 for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) {
708 ntd = TAILQ_NEXT(td, td_threadq);
709 if (td->td_wchan == ident &&
710 td->td_wdomain == (domain & PDOMAIN_MASK)
712 KKASSERT(td->td_flags & TDF_TSLEEPQ);
713 td->td_flags &= ~TDF_TSLEEPQ;
714 TAILQ_REMOVE(qp, td, td_threadq);
715 if (TAILQ_FIRST(qp) == NULL) {
716 atomic_clear_int(&slpque_cpumasks[id],
720 if (domain & PWAKEUP_ONE)
728 * We finished checking the current cpu but there still may be
729 * more work to do. Either wakeup_one was requested and no matching
730 * thread was found, or a normal wakeup was requested and we have
731 * to continue checking cpus.
733 * The cpu that started the wakeup sequence is encoded in the domain.
734 * We use this information to determine which cpus still need to be
735 * checked, locate a candidate cpu, and chain the wakeup
736 * asynchronously with an IPI message.
738 * It should be noted that this scheme is actually less expensive then
739 * the old scheme when waking up multiple threads, since we send
740 * only one IPI message per target candidate which may then schedule
741 * multiple threads. Before we could have wound up sending an IPI
742 * message for each thread on the target cpu (!= current cpu) that
743 * needed to be woken up.
745 * NOTE: Wakeups occuring on remote cpus are asynchronous. This
746 * should be ok since we are passing idents in the IPI rather then
749 if ((domain & PWAKEUP_MYCPU) == 0 &&
750 (mask = slpque_cpumasks[id]) != 0
753 * Look for a cpu that might have work to do. Mask out cpus
754 * which have already been processed.
756 * 31xxxxxxxxxxxxxxxxxxxxxxxxxxxxx0
758 * start currentcpu start
761 * 11111111111111110000000000000111 case1
762 * 00000000111111110000000000000000 case2
764 * case1: We started at start_case1 and processed through
765 * to the current cpu. We have to check any bits
766 * after the current cpu, then check bits before
769 * case2: We have already checked all the bits from
770 * start_case2 to the end, and from 0 to the current
771 * cpu. We just have the bits from the current cpu
772 * to start_case2 left to check.
774 startcpu = PWAKEUP_DECODE(domain);
775 if (gd->gd_cpuid >= startcpu) {
779 tmask = mask & ~((gd->gd_cpumask << 1) - 1);
781 nextcpu = bsfl(mask & tmask);
782 lwkt_send_ipiq2(globaldata_find(nextcpu),
783 _wakeup, ident, domain);
785 tmask = (1 << startcpu) - 1;
787 nextcpu = bsfl(mask & tmask);
789 globaldata_find(nextcpu),
790 _wakeup, ident, domain);
797 tmask = ~((gd->gd_cpumask << 1) - 1) &
798 ((1 << startcpu) - 1);
800 nextcpu = bsfl(mask & tmask);
801 lwkt_send_ipiq2(globaldata_find(nextcpu),
802 _wakeup, ident, domain);
808 logtsleep(wakeup_end);
813 * Wakeup all threads tsleep()ing on the specified ident, on all cpus
818 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid));
822 * Wakeup one thread tsleep()ing on the specified ident, on any cpu.
825 wakeup_one(void *ident)
827 /* XXX potentially round-robin the first responding cpu */
828 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid) | PWAKEUP_ONE);
832 * Wakeup threads tsleep()ing on the specified ident on the current cpu
836 wakeup_mycpu(void *ident)
838 _wakeup(ident, PWAKEUP_MYCPU);
842 * Wakeup one thread tsleep()ing on the specified ident on the current cpu
846 wakeup_mycpu_one(void *ident)
848 /* XXX potentially round-robin the first responding cpu */
849 _wakeup(ident, PWAKEUP_MYCPU|PWAKEUP_ONE);
853 * Wakeup all thread tsleep()ing on the specified ident on the specified cpu
857 wakeup_oncpu(globaldata_t gd, void *ident)
861 _wakeup(ident, PWAKEUP_MYCPU);
863 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU);
866 _wakeup(ident, PWAKEUP_MYCPU);
871 * Wakeup one thread tsleep()ing on the specified ident on the specified cpu
875 wakeup_oncpu_one(globaldata_t gd, void *ident)
879 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE);
881 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU | PWAKEUP_ONE);
884 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE);
889 * Wakeup all threads waiting on the specified ident that slept using
890 * the specified domain, on all cpus.
893 wakeup_domain(void *ident, int domain)
895 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid));
899 * Wakeup one thread waiting on the specified ident that slept using
900 * the specified domain, on any cpu.
903 wakeup_domain_one(void *ident, int domain)
905 /* XXX potentially round-robin the first responding cpu */
906 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid) | PWAKEUP_ONE);
912 * Make a process runnable. The MP lock must be held on call. This only
913 * has an effect if we are in SSLEEP. We only break out of the
914 * tsleep if LWP_BREAKTSLEEP is set, otherwise we just fix-up the state.
916 * NOTE: With the MP lock held we can only safely manipulate the process
917 * structure. We cannot safely manipulate the thread structure.
920 setrunnable(struct lwp *lp)
923 ASSERT_MP_LOCK_HELD(curthread);
924 if (lp->lwp_stat == LSSTOP)
925 lp->lwp_stat = LSSLEEP;
926 if (lp->lwp_stat == LSSLEEP && (lp->lwp_flag & LWP_BREAKTSLEEP))
927 unsleep_and_wakeup_thread(lp->lwp_thread);
932 * The process is stopped due to some condition, usually because p_stat is
933 * set to SSTOP, but also possibly due to being traced.
935 * NOTE! If the caller sets SSTOP, the caller must also clear P_WAITED
936 * because the parent may check the child's status before the child actually
937 * gets to this routine.
939 * This routine is called with the current lwp only, typically just
940 * before returning to userland.
942 * Setting LWP_BREAKTSLEEP before entering the tsleep will cause a passive
943 * SIGCONT to break out of the tsleep.
948 struct lwp *lp = curthread->td_lwp;
949 struct proc *p = lp->lwp_proc;
951 lp->lwp_flag |= LWP_BREAKTSLEEP;
952 lp->lwp_stat = LSSTOP;
955 * If LWP_WSTOP is set, we were sleeping
956 * while our process was stopped. At this point
957 * we were already counted as stopped.
959 if ((lp->lwp_flag & LWP_WSTOP) == 0) {
961 * If we're the last thread to stop, signal
965 lp->lwp_flag |= LWP_WSTOP;
966 if (p->p_nstopped == p->p_nthreads) {
967 p->p_flag &= ~P_WAITED;
969 if ((p->p_pptr->p_sigacts->ps_flag & PS_NOCLDSTOP) == 0)
970 ksignal(p->p_pptr, SIGCHLD);
973 tsleep(lp->lwp_proc, 0, "stop", 0);
979 * Yield / synchronous reschedule. This is a bit tricky because the trap
980 * code might have set a lazy release on the switch function. Setting
981 * P_PASSIVE_ACQ will ensure that the lazy release executes when we call
982 * switch, and that we are given a greater chance of affinity with our
985 * We call lwkt_setpri_self() to rotate our thread to the end of the lwkt
986 * run queue. lwkt_switch() will also execute any assigned passive release
987 * (which usually calls release_curproc()), allowing a same/higher priority
988 * process to be designated as the current process.
990 * While it is possible for a lower priority process to be designated,
991 * it's call to lwkt_maybe_switch() in acquire_curproc() will likely
992 * round-robin back to us and we will be able to re-acquire the current
993 * process designation.
998 struct thread *td = curthread;
999 struct proc *p = td->td_proc;
1001 lwkt_setpri_self(td->td_pri & TDPRI_MASK);
1003 p->p_flag |= P_PASSIVE_ACQ;
1005 p->p_flag &= ~P_PASSIVE_ACQ;
1012 * Compute a tenex style load average of a quantity on
1013 * 1, 5 and 15 minute intervals.
1015 static int loadav_count_runnable(struct lwp *p, void *data);
1020 struct loadavg *avg;
1024 alllwp_scan(loadav_count_runnable, &nrun);
1026 for (i = 0; i < 3; i++) {
1027 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
1028 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
1032 * Schedule the next update to occur after 5 seconds, but add a
1033 * random variation to avoid synchronisation with processes that
1034 * run at regular intervals.
1036 callout_reset(&loadav_callout, hz * 4 + (int)(krandom() % (hz * 2 + 1)),
1041 loadav_count_runnable(struct lwp *lp, void *data)
1046 switch (lp->lwp_stat) {
1048 if ((td = lp->lwp_thread) == NULL)
1050 if (td->td_flags & TDF_BLOCKED)
1062 sched_setup(void *dummy)
1064 callout_init(&loadav_callout);
1065 callout_init(&schedcpu_callout);
1067 /* Kick off timeout driven events by calling first time. */