/*- * 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: head/sys/kern/kern_synch.c 131481 2004-07-02 20:21:44Z jhb $"); #include "opt_ddb.h" #include "opt_ktrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DDB #include #endif #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 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 process until a wakeup is * performed on the specified identifier. The process 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 mutex argument is exited before the caller is suspended, and * entered before msleep returns. If priority includes the PDROP * flag the mutex is not entered before returning. */ int msleep(ident, mtx, priority, wmesg, timo) void *ident; struct mtx *mtx; int priority, timo; const char *wmesg; { struct sleepqueue *sq; struct thread *td; struct proc *p; int catch, rval, sig; WITNESS_SAVE_DECL(mtx); td = curthread; p = td->td_proc; #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(1, 0); #endif WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, mtx == NULL ? NULL : &mtx->mtx_object, "Sleeping on \"%s\"", wmesg); KASSERT(timo != 0 || mtx_owned(&Giant) || 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. */ if (mtx != NULL && priority & PDROP) mtx_unlock(mtx); return (0); } catch = priority & PCATCH; 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); sq = sleepq_lookup(ident); mtx_lock_spin(&sched_lock); if (p->p_flag & P_SA || p->p_numthreads > 1) { /* * Just don't bother if we are exiting * and not the exiting thread or thread was marked as * interrupted. */ if (catch) { if ((p->p_flag & P_WEXIT) && p->p_singlethread != td) { mtx_unlock_spin(&sched_lock); sleepq_release(ident); return (EINTR); } if (td->td_flags & TDF_INTERRUPT) { mtx_unlock_spin(&sched_lock); sleepq_release(ident); return (td->td_intrval); } } } mtx_unlock_spin(&sched_lock); CTR5(KTR_PROC, "msleep: thread %p (pid %ld, %s) on %s (%p)", (void *)td, (long)p->p_pid, p->p_comm, wmesg, ident); DROP_GIANT(); if (mtx != NULL) { mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); WITNESS_SAVE(&mtx->mtx_object, mtx); mtx_unlock(mtx); } /* * 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(sq, ident, mtx, wmesg, 0); if (timo) sleepq_set_timeout(ident, timo); if (catch) { sig = sleepq_catch_signals(ident); if (sig == 0 && !TD_ON_SLEEPQ(td)) { mtx_lock_spin(&sched_lock); td->td_flags &= ~TDF_SINTR; mtx_unlock_spin(&sched_lock); catch = 0; } } else sig = 0; /* * Adjust this thread's priority. * * XXX: do we need to save priority in td_base_pri? */ mtx_lock_spin(&sched_lock); sched_prio(td, priority & PRIMASK); mtx_unlock_spin(&sched_lock); if (timo && catch) rval = sleepq_timedwait_sig(ident, sig != 0); else if (timo) rval = sleepq_timedwait(ident); else if (catch) rval = sleepq_wait_sig(ident); else { sleepq_wait(ident); rval = 0; } if (rval == 0 && catch) rval = sleepq_calc_signal_retval(sig); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(0, 0); #endif PICKUP_GIANT(); if (mtx != NULL && !(priority & PDROP)) { mtx_lock(mtx); WITNESS_RESTORE(&mtx->mtx_object, mtx); } return (rval); } /* * Make all threads sleeping on the specified identifier runnable. */ void wakeup(ident) register void *ident; { sleepq_broadcast(ident, 0, -1); } /* * 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_signal(ident, 0, -1); } /* * The machine independent parts of context switching. */ void mi_switch(int flags, struct thread *newtd) { struct bintime new_switchtime; struct thread *td; struct proc *p; mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED); td = curthread; /* XXX */ 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_flags & TDF_OWEPREEMPT) != 0 && (flags & SW_INVOL) != 0 && newtd == NULL), ("mi_switch: switch in a critical section")); KASSERT((flags & (SW_INVOL | SW_VOL)) != 0, ("mi_switch: switch must be voluntary or involuntary")); if (flags & SW_VOL) p->p_stats->p_ru.ru_nvcsw++; else p->p_stats->p_ru.ru_nivcsw++; /* * Compute the amount of time during which the current * process was running, and add that to its total so far. */ binuptime(&new_switchtime); bintime_add(&p->p_runtime, &new_switchtime); bintime_sub(&p->p_runtime, PCPU_PTR(switchtime)); td->td_generation++; /* bump preempt-detect counter */ #ifdef DDB /* * Don't perform context switches from the debugger. */ if (db_active) { mtx_unlock_spin(&sched_lock); db_print_backtrace(); db_error("Context switches not allowed in the debugger"); } #endif /* * Check if the process exceeds its cpu resource allocation. If * over max, arrange to kill the process in ast(). */ if (p->p_cpulimit != RLIM_INFINITY && p->p_runtime.sec > p->p_cpulimit) { p->p_sflag |= PS_XCPU; td->td_flags |= TDF_ASTPENDING; } /* * Finish up stats for outgoing thread. */ cnt.v_swtch++; PCPU_SET(switchtime, new_switchtime); PCPU_SET(switchticks, ticks); CTR3(KTR_PROC, "mi_switch: old thread %p (pid %ld, %s)", (void *)td, (long)p->p_pid, p->p_comm); if (td->td_proc->p_flag & P_SA) thread_switchout(td); sched_switch(td, newtd); CTR3(KTR_PROC, "mi_switch: new thread %p (pid %ld, %s)", (void *)td, (long)p->p_pid, p->p_comm); /* * 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) { struct proc *p; p = td->td_proc; mtx_assert(&sched_lock, MA_OWNED); switch (p->p_state) { case PRS_ZOMBIE: panic("setrunnable(1)"); default: break; } 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 ((p->p_sflag & PS_INMEM) == 0) { if ((p->p_sflag & PS_SWAPPINGIN) == 0) { p->p_sflag |= PS_SWAPINREQ; wakeup(&proc0); } } else sched_wakeup(td); } /* * Compute a tenex style load average of a quantity on * 1, 5 and 15 minute intervals. * XXXKSE Needs complete rewrite when correct info is available. * Completely Bogus.. only works with 1:1 (but compiles ok now :-) */ 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) { struct ksegrp *kg; kg = td->td_ksegrp; mtx_assert(&Giant, MA_NOTOWNED); mtx_lock_spin(&sched_lock); sched_prio(td, PRI_MAX_TIMESHARE); mi_switch(SW_VOL, NULL); mtx_unlock_spin(&sched_lock); td->td_retval[0] = 0; return (0); }