/*- * Copyright (c) 1982, 1986, 1990, 1991, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)kern_synch.c 8.9 (Berkeley) 5/19/95 */ #include __FBSDID("$FreeBSD$"); #include "opt_ktrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef KTRACE #include #include #endif #include static void synch_setup(void *dummy); SYSINIT(synch_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, synch_setup, NULL); int hogticks; int lbolt; static int pause_wchan; static struct callout loadav_callout; static struct callout lbolt_callout; struct loadavg averunnable = { {0, 0, 0}, FSCALE }; /* load average, of runnable procs */ /* * Constants for averages over 1, 5, and 15 minutes * when sampling at 5 second intervals. */ static fixpt_t cexp[3] = { 0.9200444146293232 * FSCALE, /* exp(-1/12) */ 0.9834714538216174 * FSCALE, /* exp(-1/60) */ 0.9944598480048967 * FSCALE, /* exp(-1/180) */ }; /* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */ static int fscale __unused = FSCALE; SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, ""); static void loadav(void *arg); static void lboltcb(void *arg); void sleepinit(void) { hogticks = (hz / 10) * 2; /* Default only. */ init_sleepqueues(); } /* * General sleep call. Suspends the current thread until a wakeup is * performed on the specified identifier. The thread will then be made * runnable with the specified priority. Sleeps at most timo/hz seconds * (0 means no timeout). If pri includes PCATCH flag, signals are checked * before and after sleeping, else signals are not checked. Returns 0 if * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a * signal needs to be delivered, ERESTART is returned if the current system * call should be restarted if possible, and EINTR is returned if the system * call should be interrupted by the signal (return EINTR). * * The lock argument is unlocked before the caller is suspended, and * re-locked before _sleep() returns. If priority includes the PDROP * flag the lock is not re-locked before returning. */ int _sleep(ident, lock, priority, wmesg, timo) void *ident; struct lock_object *lock; int priority, timo; const char *wmesg; { struct thread *td; struct proc *p; struct lock_class *class; int catch, flags, lock_state, pri, rval; WITNESS_SAVE_DECL(lock_witness); td = curthread; p = td->td_proc; #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(1, 0); #endif WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, "Sleeping on \"%s\"", wmesg); KASSERT(timo != 0 || mtx_owned(&Giant) || lock != NULL || ident == &lbolt, ("sleeping without a lock")); KASSERT(p != NULL, ("msleep1")); KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); if (lock != NULL) class = LOCK_CLASS(lock); else class = NULL; if (cold) { /* * During autoconfiguration, just return; * don't run any other threads or panic below, * in case this is the idle thread and already asleep. * XXX: this used to do "s = splhigh(); splx(safepri); * splx(s);" to give interrupts a chance, but there is * no way to give interrupts a chance now. */ if (lock != NULL && priority & PDROP) class->lc_unlock(lock); return (0); } catch = priority & PCATCH; pri = priority & PRIMASK; rval = 0; /* * If we are already on a sleep queue, then remove us from that * sleep queue first. We have to do this to handle recursive * sleeps. */ if (TD_ON_SLEEPQ(td)) sleepq_remove(td, td->td_wchan); if (ident == &pause_wchan) flags = SLEEPQ_PAUSE; else flags = SLEEPQ_SLEEP; if (catch) flags |= SLEEPQ_INTERRUPTIBLE; sleepq_lock(ident); CTR5(KTR_PROC, "sleep: thread %ld (pid %ld, %s) on %s (%p)", td->td_tid, p->p_pid, td->td_name, wmesg, ident); DROP_GIANT(); if (lock != NULL && !(class->lc_flags & LC_SLEEPABLE)) { WITNESS_SAVE(lock, lock_witness); lock_state = class->lc_unlock(lock); } else /* GCC needs to follow the Yellow Brick Road */ lock_state = -1; /* * We put ourselves on the sleep queue and start our timeout * before calling thread_suspend_check, as we could stop there, * and a wakeup or a SIGCONT (or both) could occur while we were * stopped without resuming us. Thus, we must be ready for sleep * when cursig() is called. If the wakeup happens while we're * stopped, then td will no longer be on a sleep queue upon * return from cursig(). */ sleepq_add(ident, ident == &lbolt ? NULL : lock, wmesg, flags, 0); if (timo) sleepq_set_timeout(ident, timo); if (lock != NULL && class->lc_flags & LC_SLEEPABLE) { sleepq_release(ident); WITNESS_SAVE(lock, lock_witness); lock_state = class->lc_unlock(lock); sleepq_lock(ident); } if (timo && catch) rval = sleepq_timedwait_sig(ident, pri); else if (timo) rval = sleepq_timedwait(ident, pri); else if (catch) rval = sleepq_wait_sig(ident, pri); else { sleepq_wait(ident, pri); rval = 0; } #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(0, 0); #endif PICKUP_GIANT(); if (lock != NULL && !(priority & PDROP)) { class->lc_lock(lock, lock_state); WITNESS_RESTORE(lock, lock_witness); } return (rval); } int msleep_spin(ident, mtx, wmesg, timo) void *ident; struct mtx *mtx; const char *wmesg; int timo; { struct thread *td; struct proc *p; int rval; WITNESS_SAVE_DECL(mtx); td = curthread; p = td->td_proc; KASSERT(mtx != NULL, ("sleeping without a mutex")); KASSERT(p != NULL, ("msleep1")); KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); if (cold) { /* * During autoconfiguration, just return; * don't run any other threads or panic below, * in case this is the idle thread and already asleep. * XXX: this used to do "s = splhigh(); splx(safepri); * splx(s);" to give interrupts a chance, but there is * no way to give interrupts a chance now. */ return (0); } sleepq_lock(ident); CTR5(KTR_PROC, "msleep_spin: thread %ld (pid %ld, %s) on %s (%p)", td->td_tid, p->p_pid, td->td_name, wmesg, ident); DROP_GIANT(); mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); WITNESS_SAVE(&mtx->lock_object, mtx); mtx_unlock_spin(mtx); /* * We put ourselves on the sleep queue and start our timeout. */ sleepq_add(ident, &mtx->lock_object, wmesg, SLEEPQ_SLEEP, 0); if (timo) sleepq_set_timeout(ident, timo); /* * Can't call ktrace with any spin locks held so it can lock the * ktrace_mtx lock, and WITNESS_WARN considers it an error to hold * any spin lock. Thus, we have to drop the sleepq spin lock while * we handle those requests. This is safe since we have placed our * thread on the sleep queue already. */ #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) { sleepq_release(ident); ktrcsw(1, 0); sleepq_lock(ident); } #endif #ifdef WITNESS sleepq_release(ident); WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "Sleeping on \"%s\"", wmesg); sleepq_lock(ident); #endif if (timo) rval = sleepq_timedwait(ident, 0); else { sleepq_wait(ident, 0); rval = 0; } #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(0, 0); #endif PICKUP_GIANT(); mtx_lock_spin(mtx); WITNESS_RESTORE(&mtx->lock_object, mtx); return (rval); } /* * pause() is like tsleep() except that the intention is to not be * explicitly woken up by another thread. Instead, the current thread * simply wishes to sleep until the timeout expires. It is * implemented using a dummy wait channel. */ int pause(wmesg, timo) const char *wmesg; int timo; { KASSERT(timo != 0, ("pause: timeout required")); return (tsleep(&pause_wchan, 0, wmesg, timo)); } /* * Make all threads sleeping on the specified identifier runnable. */ void wakeup(ident) register void *ident; { sleepq_lock(ident); sleepq_broadcast(ident, SLEEPQ_SLEEP, 0, 0); sleepq_release(ident); } /* * Make a thread sleeping on the specified identifier runnable. * May wake more than one thread if a target thread is currently * swapped out. */ void wakeup_one(ident) register void *ident; { sleepq_lock(ident); sleepq_signal(ident, SLEEPQ_SLEEP, 0, 0); sleepq_release(ident); } static void kdb_switch(void) { thread_unlock(curthread); kdb_backtrace(); kdb_reenter(); panic("%s: did not reenter debugger", __func__); } /* * The machine independent parts of context switching. */ void mi_switch(int flags, struct thread *newtd) { uint64_t runtime, new_switchtime; struct thread *td; struct proc *p; td = curthread; /* XXX */ THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED); p = td->td_proc; /* XXX */ KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code")); #ifdef INVARIANTS if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td)) mtx_assert(&Giant, MA_NOTOWNED); #endif KASSERT(td->td_critnest == 1 || (td->td_critnest == 2 && (td->td_owepreempt) && (flags & SW_INVOL) != 0 && newtd == NULL) || panicstr, ("mi_switch: switch in a critical section")); KASSERT((flags & (SW_INVOL | SW_VOL)) != 0, ("mi_switch: switch must be voluntary or involuntary")); KASSERT(newtd != curthread, ("mi_switch: preempting back to ourself")); /* * Don't perform context switches from the debugger. */ if (kdb_active) kdb_switch(); if (flags & SW_VOL) td->td_ru.ru_nvcsw++; else td->td_ru.ru_nivcsw++; /* * Compute the amount of time during which the current * thread was running, and add that to its total so far. */ new_switchtime = cpu_ticks(); runtime = new_switchtime - PCPU_GET(switchtime); td->td_runtime += runtime; td->td_incruntime += runtime; PCPU_SET(switchtime, new_switchtime); td->td_generation++; /* bump preempt-detect counter */ PCPU_INC(cnt.v_swtch); PCPU_SET(switchticks, ticks); CTR4(KTR_PROC, "mi_switch: old thread %ld (td_sched %p, pid %ld, %s)", td->td_tid, td->td_sched, p->p_pid, td->td_name); #if (KTR_COMPILE & KTR_SCHED) != 0 if (TD_IS_IDLETHREAD(td)) CTR3(KTR_SCHED, "mi_switch: %p(%s) prio %d idle", td, td->td_name, td->td_priority); else if (newtd != NULL) CTR5(KTR_SCHED, "mi_switch: %p(%s) prio %d preempted by %p(%s)", td, td->td_name, td->td_priority, newtd, newtd->td_name); else CTR6(KTR_SCHED, "mi_switch: %p(%s) prio %d inhibit %d wmesg %s lock %s", td, td->td_name, td->td_priority, td->td_inhibitors, td->td_wmesg, td->td_lockname); #endif sched_switch(td, newtd, flags); CTR3(KTR_SCHED, "mi_switch: running %p(%s) prio %d", td, td->td_name, td->td_priority); CTR4(KTR_PROC, "mi_switch: new thread %ld (td_sched %p, pid %ld, %s)", td->td_tid, td->td_sched, p->p_pid, td->td_name); /* * If the last thread was exiting, finish cleaning it up. */ if ((td = PCPU_GET(deadthread))) { PCPU_SET(deadthread, NULL); thread_stash(td); } } /* * Change process state to be runnable, * placing it on the run queue if it is in memory, * and awakening the swapper if it isn't in memory. */ void setrunnable(struct thread *td) { THREAD_LOCK_ASSERT(td, MA_OWNED); KASSERT(td->td_proc->p_state != PRS_ZOMBIE, ("setrunnable: pid %d is a zombie", td->td_proc->p_pid)); switch (td->td_state) { case TDS_RUNNING: case TDS_RUNQ: return; case TDS_INHIBITED: /* * If we are only inhibited because we are swapped out * then arange to swap in this process. Otherwise just return. */ if (td->td_inhibitors != TDI_SWAPPED) return; /* XXX: intentional fall-through ? */ case TDS_CAN_RUN: break; default: printf("state is 0x%x", td->td_state); panic("setrunnable(2)"); } if ((td->td_flags & TDF_INMEM) == 0) { if ((td->td_flags & TDF_SWAPINREQ) == 0) { td->td_flags |= TDF_SWAPINREQ; /* * due to a LOR between the thread lock and * the sleepqueue chain locks, use * lower level scheduling functions. */ kick_proc0(); } } else sched_wakeup(td); } /* * Compute a tenex style load average of a quantity on * 1, 5 and 15 minute intervals. */ static void loadav(void *arg) { int i, nrun; struct loadavg *avg; nrun = sched_load(); avg = &averunnable; for (i = 0; i < 3; i++) avg->ldavg[i] = (cexp[i] * avg->ldavg[i] + nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT; /* * Schedule the next update to occur after 5 seconds, but add a * random variation to avoid synchronisation with processes that * run at regular intervals. */ callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)), loadav, NULL); } static void lboltcb(void *arg) { wakeup(&lbolt); callout_reset(&lbolt_callout, hz, lboltcb, NULL); } /* ARGSUSED */ static void synch_setup(dummy) void *dummy; { callout_init(&loadav_callout, CALLOUT_MPSAFE); callout_init(&lbolt_callout, CALLOUT_MPSAFE); /* Kick off timeout driven events by calling first time. */ loadav(NULL); lboltcb(NULL); } /* * General purpose yield system call. */ int yield(struct thread *td, struct yield_args *uap) { thread_lock(td); sched_prio(td, PRI_MAX_TIMESHARE); mi_switch(SW_VOL, NULL); thread_unlock(td); td->td_retval[0] = 0; return (0); }