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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 1.82 2007/03/12 21:08:15 corecode 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;
81 static struct callout loadav_callout;
82 static struct callout schedcpu_callout;
83 MALLOC_DEFINE(M_TSLEEP, "tslpque", "tsleep queues");
85 #if !defined(KTR_TSLEEP)
86 #define KTR_TSLEEP KTR_ALL
88 KTR_INFO_MASTER(tsleep);
89 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_beg, 0, "tsleep enter", 0);
90 KTR_INFO(KTR_TSLEEP, tsleep, tsleep_end, 0, "tsleep exit", 0);
91 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_beg, 0, "wakeup enter", 0);
92 KTR_INFO(KTR_TSLEEP, tsleep, wakeup_end, 0, "wakeup exit", 0);
93 #define logtsleep(name) KTR_LOG(tsleep_ ## name)
95 struct loadavg averunnable =
96 { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */
98 * Constants for averages over 1, 5, and 15 minutes
99 * when sampling at 5 second intervals.
101 static fixpt_t cexp[3] = {
102 0.9200444146293232 * FSCALE, /* exp(-1/12) */
103 0.9834714538216174 * FSCALE, /* exp(-1/60) */
104 0.9944598480048967 * FSCALE, /* exp(-1/180) */
107 static void endtsleep (void *);
108 static void unsleep_and_wakeup_thread(struct thread *td);
109 static void loadav (void *arg);
110 static void schedcpu (void *arg);
113 * Adjust the scheduler quantum. The quantum is specified in microseconds.
114 * Note that 'tick' is in microseconds per tick.
117 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
121 new_val = sched_quantum * tick;
122 error = sysctl_handle_int(oidp, &new_val, 0, req);
123 if (error != 0 || req->newptr == NULL)
127 sched_quantum = new_val / tick;
128 hogticks = 2 * sched_quantum;
132 SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW,
133 0, sizeof sched_quantum, sysctl_kern_quantum, "I", "");
136 * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
137 * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
138 * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
140 * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
141 * 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
143 * If you don't want to bother with the faster/more-accurate formula, you
144 * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
145 * (more general) method of calculating the %age of CPU used by a process.
147 * decay 95% of `lwp_pctcpu' in 60 seconds; see CCPU_SHIFT before changing
149 #define CCPU_SHIFT 11
151 static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
152 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
155 * kernel uses `FSCALE', userland (SHOULD) use kern.fscale
157 int fscale __unused = FSCALE; /* exported to systat */
158 SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, "");
161 * Recompute process priorities, once a second.
163 * Since the userland schedulers are typically event oriented, if the
164 * estcpu calculation at wakeup() time is not sufficient to make a
165 * process runnable relative to other processes in the system we have
166 * a 1-second recalc to help out.
168 * This code also allows us to store sysclock_t data in the process structure
169 * without fear of an overrun, since sysclock_t are guarenteed to hold
170 * several seconds worth of count.
172 * WARNING! callouts can preempt normal threads. However, they will not
173 * preempt a thread holding a spinlock so we *can* safely use spinlocks.
175 static int schedcpu_stats(struct proc *p, void *data __unused);
176 static int schedcpu_resource(struct proc *p, void *data __unused);
181 allproc_scan(schedcpu_stats, NULL);
182 allproc_scan(schedcpu_resource, NULL);
183 wakeup((caddr_t)&lbolt);
184 wakeup((caddr_t)&lbolt_syncer);
185 callout_reset(&schedcpu_callout, hz, schedcpu, NULL);
189 * General process statistics once a second
192 schedcpu_stats(struct proc *p, void *data __unused)
198 FOREACH_LWP_IN_PROC(lp, p) {
199 if (lp->lwp_stat == LSSLEEP)
203 * Only recalculate processes that are active or have slept
204 * less then 2 seconds. The schedulers understand this.
206 if (lp->lwp_slptime <= 1) {
207 p->p_usched->recalculate(lp);
209 lp->lwp_pctcpu = (lp->lwp_pctcpu * ccpu) >> FSHIFT;
217 * Resource checks. XXX break out since ksignal/killproc can block,
218 * limiting us to one process killed per second. There is probably
222 schedcpu_resource(struct proc *p, void *data __unused)
228 if (p->p_stat == SIDL ||
229 p->p_stat == SZOMB ||
237 FOREACH_LWP_IN_PROC(lp, p) {
238 ttime += lp->lwp_thread->td_sticks;
239 ttime += lp->lwp_thread->td_uticks;
242 switch(plimit_testcpulimit(p->p_limit, ttime)) {
243 case PLIMIT_TESTCPU_KILL:
244 killproc(p, "exceeded maximum CPU limit");
246 case PLIMIT_TESTCPU_XCPU:
247 if ((p->p_flag & P_XCPU) == 0) {
260 * This is only used by ps. Generate a cpu percentage use over
261 * a period of one second.
266 updatepcpu(struct lwp *lp, int cpticks, int ttlticks)
271 acc = (cpticks << FSHIFT) / ttlticks;
272 if (ttlticks >= ESTCPUFREQ) {
273 lp->lwp_pctcpu = acc;
275 remticks = ESTCPUFREQ - ttlticks;
276 lp->lwp_pctcpu = (acc * ttlticks + lp->lwp_pctcpu * remticks) /
282 * We're only looking at 7 bits of the address; everything is
283 * aligned to 4, lots of things are aligned to greater powers
284 * of 2. Shift right by 8, i.e. drop the bottom 256 worth.
286 #define TABLESIZE 128
287 #define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1))
289 static cpumask_t slpque_cpumasks[TABLESIZE];
292 * General scheduler initialization. We force a reschedule 25 times
293 * a second by default. Note that cpu0 is initialized in early boot and
294 * cannot make any high level calls.
296 * Each cpu has its own sleep queue.
299 sleep_gdinit(globaldata_t gd)
301 static struct tslpque slpque_cpu0[TABLESIZE];
304 if (gd->gd_cpuid == 0) {
305 sched_quantum = (hz + 24) / 25;
306 hogticks = 2 * sched_quantum;
308 gd->gd_tsleep_hash = slpque_cpu0;
310 gd->gd_tsleep_hash = kmalloc(sizeof(slpque_cpu0),
311 M_TSLEEP, M_WAITOK | M_ZERO);
313 for (i = 0; i < TABLESIZE; ++i)
314 TAILQ_INIT(&gd->gd_tsleep_hash[i]);
318 * General sleep call. Suspends the current process until a wakeup is
319 * performed on the specified identifier. The process will then be made
320 * runnable with the specified priority. Sleeps at most timo/hz seconds
321 * (0 means no timeout). If flags includes PCATCH flag, signals are checked
322 * before and after sleeping, else signals are not checked. Returns 0 if
323 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a
324 * signal needs to be delivered, ERESTART is returned if the current system
325 * call should be restarted if possible, and EINTR is returned if the system
326 * call should be interrupted by the signal (return EINTR).
328 * Note that if we are a process, we release_curproc() before messing with
329 * the LWKT scheduler.
331 * During autoconfiguration or after a panic, a sleep will simply
332 * lower the priority briefly to allow interrupts, then return.
335 tsleep(void *ident, int flags, const char *wmesg, int timo)
337 struct thread *td = curthread;
338 struct lwp *lp = td->td_lwp;
339 struct proc *p = td->td_proc; /* may be NULL */
346 struct callout thandle;
349 * NOTE: removed KTRPOINT, it could cause races due to blocking
350 * even in stable. Just scrap it for now.
352 if (cold || panicstr) {
354 * After a panic, or during autoconfiguration,
355 * just give interrupts a chance, then just return;
356 * don't run any other procs or panic below,
357 * in case this is the idle process and already asleep.
360 oldpri = td->td_pri & TDPRI_MASK;
361 lwkt_setpri_self(safepri);
363 lwkt_setpri_self(oldpri);
366 logtsleep(tsleep_beg);
368 KKASSERT(td != &gd->gd_idlethread); /* you must be kidding! */
371 * NOTE: all of this occurs on the current cpu, including any
372 * callout-based wakeups, so a critical section is a sufficient
375 * The entire sequence through to where we actually sleep must
376 * run without breaking the critical section.
379 catch = flags & PCATCH;
383 crit_enter_quick(td);
385 KASSERT(ident != NULL, ("tsleep: no ident"));
386 KASSERT(lp == NULL ||
387 lp->lwp_stat == LSRUN || /* Obvious */
388 lp->lwp_stat == LSSTOP, /* Set in tstop */
390 ident, wmesg, lp->lwp_stat));
393 * Setup for the current process (if this is a process).
398 * Early termination if PCATCH was set and a
399 * signal is pending, interlocked with the
402 * Early termination only occurs when tsleep() is
403 * entered while in a normal LSRUN state.
405 if ((sig = CURSIG(lp)) != 0)
409 * Early termination if PCATCH was set and a
410 * mailbox signal was possibly delivered prior to
411 * the system call even being made, in order to
412 * allow the user to interlock without having to
413 * make additional system calls.
415 if (p->p_flag & P_MAILBOX)
419 * Causes ksignal to wake us up when.
421 lp->lwp_flag |= LWP_SINTR;
425 * Make sure the current process has been untangled from
426 * the userland scheduler and initialize slptime to start
429 if (flags & PNORESCHED)
430 td->td_flags |= TDF_NORESCHED;
431 p->p_usched->release_curproc(lp);
436 * Move our thread to the correct queue and setup our wchan, etc.
438 lwkt_deschedule_self(td);
439 td->td_flags |= TDF_TSLEEPQ;
440 TAILQ_INSERT_TAIL(&gd->gd_tsleep_hash[id], td, td_threadq);
441 atomic_set_int(&slpque_cpumasks[id], gd->gd_cpumask);
443 td->td_wchan = ident;
444 td->td_wmesg = wmesg;
445 td->td_wdomain = flags & PDOMAIN_MASK;
448 * Setup the timeout, if any
451 callout_init(&thandle);
452 callout_reset(&thandle, timo, endtsleep, td);
460 * Ok, we are sleeping. Place us in the SSLEEP state.
462 KKASSERT((lp->lwp_flag & LWP_ONRUNQ) == 0);
464 * tstop() sets LSSTOP, so don't fiddle with that.
466 if (lp->lwp_stat != LSSTOP)
467 lp->lwp_stat = LSSLEEP;
468 lp->lwp_ru.ru_nvcsw++;
472 * And when we are woken up, put us back in LSRUN. If we
473 * slept for over a second, recalculate our estcpu.
475 lp->lwp_stat = LSRUN;
477 p->p_usched->recalculate(lp);
484 * Make sure we haven't switched cpus while we were asleep. It's
485 * not supposed to happen. Cleanup our temporary flags.
487 KKASSERT(gd == td->td_gd);
488 td->td_flags &= ~TDF_NORESCHED;
491 * Cleanup the timeout.
494 if (td->td_flags & TDF_TIMEOUT) {
495 td->td_flags &= ~TDF_TIMEOUT;
498 callout_stop(&thandle);
503 * Since td_threadq is used both for our run queue AND for the
504 * tsleep hash queue, we can't still be on it at this point because
505 * we've gotten cpu back.
507 KASSERT((td->td_flags & TDF_TSLEEPQ) == 0, ("tsleep: impossible thread flags %08x", td->td_flags));
513 * Figure out the correct error return. If interrupted by a
514 * signal we want to return EINTR or ERESTART.
516 * If P_MAILBOX is set no automatic system call restart occurs
517 * and we return EINTR. P_MAILBOX is meant to be used as an
518 * interlock, the user must poll it prior to any system call
519 * that it wishes to interlock a mailbox signal against since
520 * the flag is cleared on *any* system call that sleeps.
524 if (catch && error == 0) {
525 if ((p->p_flag & P_MAILBOX) && sig == 0) {
527 } else if (sig != 0 || (sig = CURSIG(lp))) {
528 if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
534 lp->lwp_flag &= ~(LWP_BREAKTSLEEP | LWP_SINTR);
535 p->p_flag &= ~P_MAILBOX;
537 logtsleep(tsleep_end);
543 * This is a dandy function that allows us to interlock tsleep/wakeup
544 * operations with unspecified upper level locks, such as lockmgr locks,
545 * simply by holding a critical section. The sequence is:
547 * (enter critical section)
548 * (acquire upper level lock)
549 * tsleep_interlock(blah)
550 * (release upper level lock)
552 * (exit critical section)
554 * Basically this function sets our cpumask for the ident which informs
555 * other cpus that our cpu 'might' be waiting (or about to wait on) the
556 * hash index related to the ident. The critical section prevents another
557 * cpu's wakeup() from being processed on our cpu until we are actually
558 * able to enter the tsleep(). Thus, no race occurs between our attempt
559 * to release a resource and sleep, and another cpu's attempt to acquire
560 * a resource and call wakeup.
562 * There isn't much of a point to this function unless you call it while
563 * holding a critical section.
566 _tsleep_interlock(globaldata_t gd, void *ident)
568 int id = LOOKUP(ident);
570 atomic_set_int(&slpque_cpumasks[id], gd->gd_cpumask);
574 tsleep_interlock(void *ident)
576 _tsleep_interlock(mycpu, ident);
580 * Interlocked spinlock sleep. An exclusively held spinlock must
581 * be passed to msleep(). The function will atomically release the
582 * spinlock and tsleep on the ident, then reacquire the spinlock and
585 * This routine is fairly important along the critical path, so optimize it
589 msleep(void *ident, struct spinlock *spin, int flags,
590 const char *wmesg, int timo)
592 globaldata_t gd = mycpu;
596 _tsleep_interlock(gd, ident);
597 spin_unlock_wr_quick(gd, spin);
598 error = tsleep(ident, flags, wmesg, timo);
599 spin_lock_wr_quick(gd, spin);
606 * Implement the timeout for tsleep.
608 * We set LWP_BREAKTSLEEP to indicate that an event has occured, but
609 * we only call setrunnable if the process is not stopped.
611 * This type of callout timeout is scheduled on the same cpu the process
612 * is sleeping on. Also, at the moment, the MP lock is held.
620 ASSERT_MP_LOCK_HELD(curthread);
624 * cpu interlock. Thread flags are only manipulated on
625 * the cpu owning the thread. proc flags are only manipulated
626 * by the older of the MP lock. We have both.
628 if (td->td_flags & TDF_TSLEEPQ) {
629 td->td_flags |= TDF_TIMEOUT;
631 if ((lp = td->td_lwp) != NULL) {
632 lp->lwp_flag |= LWP_BREAKTSLEEP;
633 if (lp->lwp_proc->p_stat != SSTOP)
636 unsleep_and_wakeup_thread(td);
643 * Unsleep and wakeup a thread. This function runs without the MP lock
644 * which means that it can only manipulate thread state on the owning cpu,
645 * and cannot touch the process state at all.
649 unsleep_and_wakeup_thread(struct thread *td)
651 globaldata_t gd = mycpu;
655 if (td->td_gd != gd) {
656 lwkt_send_ipiq(td->td_gd, (ipifunc1_t)unsleep_and_wakeup_thread, td);
661 if (td->td_flags & TDF_TSLEEPQ) {
662 td->td_flags &= ~TDF_TSLEEPQ;
663 id = LOOKUP(td->td_wchan);
664 TAILQ_REMOVE(&gd->gd_tsleep_hash[id], td, td_threadq);
665 if (TAILQ_FIRST(&gd->gd_tsleep_hash[id]) == NULL)
666 atomic_clear_int(&slpque_cpumasks[id], gd->gd_cpumask);
673 * Make all processes sleeping on the specified identifier runnable.
674 * count may be zero or one only.
676 * The domain encodes the sleep/wakeup domain AND the first cpu to check
677 * (which is always the current cpu). As we iterate across cpus
679 * This call may run without the MP lock held. We can only manipulate thread
680 * state on the cpu owning the thread. We CANNOT manipulate process state
684 _wakeup(void *ident, int domain)
699 logtsleep(wakeup_beg);
702 qp = &gd->gd_tsleep_hash[id];
704 for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) {
705 ntd = TAILQ_NEXT(td, td_threadq);
706 if (td->td_wchan == ident &&
707 td->td_wdomain == (domain & PDOMAIN_MASK)
709 KKASSERT(td->td_flags & TDF_TSLEEPQ);
710 td->td_flags &= ~TDF_TSLEEPQ;
711 TAILQ_REMOVE(qp, td, td_threadq);
712 if (TAILQ_FIRST(qp) == NULL) {
713 atomic_clear_int(&slpque_cpumasks[id],
717 if (domain & PWAKEUP_ONE)
725 * We finished checking the current cpu but there still may be
726 * more work to do. Either wakeup_one was requested and no matching
727 * thread was found, or a normal wakeup was requested and we have
728 * to continue checking cpus.
730 * The cpu that started the wakeup sequence is encoded in the domain.
731 * We use this information to determine which cpus still need to be
732 * checked, locate a candidate cpu, and chain the wakeup
733 * asynchronously with an IPI message.
735 * It should be noted that this scheme is actually less expensive then
736 * the old scheme when waking up multiple threads, since we send
737 * only one IPI message per target candidate which may then schedule
738 * multiple threads. Before we could have wound up sending an IPI
739 * message for each thread on the target cpu (!= current cpu) that
740 * needed to be woken up.
742 * NOTE: Wakeups occuring on remote cpus are asynchronous. This
743 * should be ok since we are passing idents in the IPI rather then
746 if ((domain & PWAKEUP_MYCPU) == 0 &&
747 (mask = slpque_cpumasks[id]) != 0
750 * Look for a cpu that might have work to do. Mask out cpus
751 * which have already been processed.
753 * 31xxxxxxxxxxxxxxxxxxxxxxxxxxxxx0
755 * start currentcpu start
758 * 11111111111111110000000000000111 case1
759 * 00000000111111110000000000000000 case2
761 * case1: We started at start_case1 and processed through
762 * to the current cpu. We have to check any bits
763 * after the current cpu, then check bits before
766 * case2: We have already checked all the bits from
767 * start_case2 to the end, and from 0 to the current
768 * cpu. We just have the bits from the current cpu
769 * to start_case2 left to check.
771 startcpu = PWAKEUP_DECODE(domain);
772 if (gd->gd_cpuid >= startcpu) {
776 tmask = mask & ~((gd->gd_cpumask << 1) - 1);
778 nextcpu = bsfl(mask & tmask);
779 lwkt_send_ipiq2(globaldata_find(nextcpu),
780 _wakeup, ident, domain);
782 tmask = (1 << startcpu) - 1;
784 nextcpu = bsfl(mask & tmask);
786 globaldata_find(nextcpu),
787 _wakeup, ident, domain);
794 tmask = ~((gd->gd_cpumask << 1) - 1) &
795 ((1 << startcpu) - 1);
797 nextcpu = bsfl(mask & tmask);
798 lwkt_send_ipiq2(globaldata_find(nextcpu),
799 _wakeup, ident, domain);
805 logtsleep(wakeup_end);
810 * Wakeup all threads tsleep()ing on the specified ident, on all cpus
815 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid));
819 * Wakeup one thread tsleep()ing on the specified ident, on any cpu.
822 wakeup_one(void *ident)
824 /* XXX potentially round-robin the first responding cpu */
825 _wakeup(ident, PWAKEUP_ENCODE(0, mycpu->gd_cpuid) | PWAKEUP_ONE);
829 * Wakeup threads tsleep()ing on the specified ident on the current cpu
833 wakeup_mycpu(void *ident)
835 _wakeup(ident, PWAKEUP_MYCPU);
839 * Wakeup one thread tsleep()ing on the specified ident on the current cpu
843 wakeup_mycpu_one(void *ident)
845 /* XXX potentially round-robin the first responding cpu */
846 _wakeup(ident, PWAKEUP_MYCPU|PWAKEUP_ONE);
850 * Wakeup all thread tsleep()ing on the specified ident on the specified cpu
854 wakeup_oncpu(globaldata_t gd, void *ident)
858 _wakeup(ident, PWAKEUP_MYCPU);
860 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU);
863 _wakeup(ident, PWAKEUP_MYCPU);
868 * Wakeup one thread tsleep()ing on the specified ident on the specified cpu
872 wakeup_oncpu_one(globaldata_t gd, void *ident)
876 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE);
878 lwkt_send_ipiq2(gd, _wakeup, ident, PWAKEUP_MYCPU | PWAKEUP_ONE);
881 _wakeup(ident, PWAKEUP_MYCPU | PWAKEUP_ONE);
886 * Wakeup all threads waiting on the specified ident that slept using
887 * the specified domain, on all cpus.
890 wakeup_domain(void *ident, int domain)
892 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid));
896 * Wakeup one thread waiting on the specified ident that slept using
897 * the specified domain, on any cpu.
900 wakeup_domain_one(void *ident, int domain)
902 /* XXX potentially round-robin the first responding cpu */
903 _wakeup(ident, PWAKEUP_ENCODE(domain, mycpu->gd_cpuid) | PWAKEUP_ONE);
909 * Make a process runnable. The MP lock must be held on call. This only
910 * has an effect if we are in SSLEEP. We only break out of the
911 * tsleep if LWP_BREAKTSLEEP is set, otherwise we just fix-up the state.
913 * NOTE: With the MP lock held we can only safely manipulate the process
914 * structure. We cannot safely manipulate the thread structure.
917 setrunnable(struct lwp *lp)
920 ASSERT_MP_LOCK_HELD(curthread);
921 if (lp->lwp_stat == LSSTOP)
922 lp->lwp_stat = LSSLEEP;
923 if (lp->lwp_stat == LSSLEEP && (lp->lwp_flag & LWP_BREAKTSLEEP))
924 unsleep_and_wakeup_thread(lp->lwp_thread);
929 * The process is stopped due to some condition, usually because p_stat is
930 * set to SSTOP, but also possibly due to being traced.
932 * NOTE! If the caller sets SSTOP, the caller must also clear P_WAITED
933 * because the parent may check the child's status before the child actually
934 * gets to this routine.
936 * This routine is called with the current lwp only, typically just
937 * before returning to userland.
939 * Setting LWP_BREAKTSLEEP before entering the tsleep will cause a passive
940 * SIGCONT to break out of the tsleep.
945 struct lwp *lp = curthread->td_lwp;
946 struct proc *p = lp->lwp_proc;
948 lp->lwp_flag |= LWP_BREAKTSLEEP;
949 lp->lwp_stat = LSSTOP;
952 * If LWP_WSTOP is set, we were sleeping
953 * while our process was stopped. At this point
954 * we were already counted as stopped.
956 if ((lp->lwp_flag & LWP_WSTOP) == 0) {
958 * If we're the last thread to stop, signal
962 lp->lwp_flag |= LWP_WSTOP;
963 if (p->p_nstopped == p->p_nthreads) {
964 p->p_flag &= ~P_WAITED;
966 if ((p->p_pptr->p_sigacts->ps_flag & PS_NOCLDSTOP) == 0)
967 ksignal(p->p_pptr, SIGCHLD);
970 tsleep(lp->lwp_proc, 0, "stop", 0);
976 * Yield / synchronous reschedule. This is a bit tricky because the trap
977 * code might have set a lazy release on the switch function. Setting
978 * P_PASSIVE_ACQ will ensure that the lazy release executes when we call
979 * switch, and that we are given a greater chance of affinity with our
982 * We call lwkt_setpri_self() to rotate our thread to the end of the lwkt
983 * run queue. lwkt_switch() will also execute any assigned passive release
984 * (which usually calls release_curproc()), allowing a same/higher priority
985 * process to be designated as the current process.
987 * While it is possible for a lower priority process to be designated,
988 * it's call to lwkt_maybe_switch() in acquire_curproc() will likely
989 * round-robin back to us and we will be able to re-acquire the current
990 * process designation.
995 struct thread *td = curthread;
996 struct proc *p = td->td_proc;
998 lwkt_setpri_self(td->td_pri & TDPRI_MASK);
1000 p->p_flag |= P_PASSIVE_ACQ;
1002 p->p_flag &= ~P_PASSIVE_ACQ;
1009 * Compute a tenex style load average of a quantity on
1010 * 1, 5 and 15 minute intervals.
1012 static int loadav_count_runnable(struct lwp *p, void *data);
1017 struct loadavg *avg;
1021 alllwp_scan(loadav_count_runnable, &nrun);
1023 for (i = 0; i < 3; i++) {
1024 avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
1025 nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
1029 * Schedule the next update to occur after 5 seconds, but add a
1030 * random variation to avoid synchronisation with processes that
1031 * run at regular intervals.
1033 callout_reset(&loadav_callout, hz * 4 + (int)(krandom() % (hz * 2 + 1)),
1038 loadav_count_runnable(struct lwp *lp, void *data)
1043 switch (lp->lwp_stat) {
1045 if ((td = lp->lwp_thread) == NULL)
1047 if (td->td_flags & TDF_BLOCKED)
1059 sched_setup(void *dummy)
1061 callout_init(&loadav_callout);
1062 callout_init(&schedcpu_callout);
1064 /* Kick off timeout driven events by calling first time. */