/*- * 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 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 116963 2003-06-28 08:29:05Z davidxu $"); #include "opt_ddb.h" #include "opt_ktrace.h" #ifdef __i386__ #include "opt_swtch.h" #endif #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 sched_setup(void *dummy); SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_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 endtsleep(void *); static void loadav(void *arg); static void lboltcb(void *arg); /* * We're only looking at 7 bits of the address; everything is * aligned to 4, lots of things are aligned to greater powers * of 2. Shift right by 8, i.e. drop the bottom 256 worth. */ #define TABLESIZE 128 static TAILQ_HEAD(slpquehead, thread) slpque[TABLESIZE]; #define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1)) void sleepinit(void) { int i; hogticks = (hz / 10) * 2; /* Default only. */ for (i = 0; i < TABLESIZE; i++) TAILQ_INIT(&slpque[i]); } /* * 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 thread *td = curthread; struct proc *p = td->td_proc; int sig, catch = priority & PCATCH; int rval = 0; WITNESS_SAVE_DECL(mtx); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(1, 0); #endif /* XXX: mtx == NULL ?? */ WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mtx->mtx_object, "Sleeping on \"%s\"", wmesg); KASSERT(timo != 0 || mtx_owned(&Giant) || mtx != NULL, ("sleeping without a mutex")); /* * If we are capable of async syscalls and there isn't already * another one ready to return, start a new thread * and queue it as ready to run. Note that there is danger here * because we need to make sure that we don't sleep allocating * the thread (recursion here might be bad). */ 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); return (EINTR); } if (td->td_flags & TDF_INTERRUPT) { mtx_unlock_spin(&sched_lock); return (td->td_intrval); } } } if (cold ) { /* * During autoconfiguration, just give interrupts * a chance, then just return. * Don't run any other procs or panic below, * in case this is the idle process and already asleep. */ if (mtx != NULL && priority & PDROP) mtx_unlock(mtx); mtx_unlock_spin(&sched_lock); return (0); } DROP_GIANT(); if (mtx != NULL) { mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED); WITNESS_SAVE(&mtx->mtx_object, mtx); mtx_unlock(mtx); if (priority & PDROP) mtx = NULL; } KASSERT(p != NULL, ("msleep1")); KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep")); CTR5(KTR_PROC, "msleep: thread %p (pid %d, %s) on %s (%p)", td, p->p_pid, p->p_comm, wmesg, ident); td->td_wchan = ident; td->td_wmesg = wmesg; TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], td, td_slpq); TD_SET_ON_SLEEPQ(td); if (timo) callout_reset(&td->td_slpcallout, timo, endtsleep, td); /* * 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, td->td_wchan will be 0 upon return from cursig. */ if (catch) { CTR3(KTR_PROC, "msleep caught: thread %p (pid %d, %s)", td, p->p_pid, p->p_comm); td->td_flags |= TDF_SINTR; mtx_unlock_spin(&sched_lock); PROC_LOCK(p); mtx_lock(&p->p_sigacts->ps_mtx); sig = cursig(td); mtx_unlock(&p->p_sigacts->ps_mtx); if (sig == 0 && thread_suspend_check(1)) sig = SIGSTOP; mtx_lock_spin(&sched_lock); PROC_UNLOCK(p); if (sig != 0) { if (TD_ON_SLEEPQ(td)) unsleep(td); } else if (!TD_ON_SLEEPQ(td)) catch = 0; } else sig = 0; /* * Let the scheduler know we're about to voluntarily go to sleep. */ sched_sleep(td, priority & PRIMASK); if (TD_ON_SLEEPQ(td)) { p->p_stats->p_ru.ru_nvcsw++; TD_SET_SLEEPING(td); mi_switch(); } /* * We're awake from voluntary sleep. */ CTR3(KTR_PROC, "msleep resume: thread %p (pid %d, %s)", td, p->p_pid, p->p_comm); KASSERT(TD_IS_RUNNING(td), ("running but not TDS_RUNNING")); td->td_flags &= ~TDF_SINTR; if (td->td_flags & TDF_TIMEOUT) { td->td_flags &= ~TDF_TIMEOUT; if (sig == 0) rval = EWOULDBLOCK; } else if (td->td_flags & TDF_TIMOFAIL) { td->td_flags &= ~TDF_TIMOFAIL; } else if (timo && callout_stop(&td->td_slpcallout) == 0) { /* * This isn't supposed to be pretty. If we are here, then * the endtsleep() callout is currently executing on another * CPU and is either spinning on the sched_lock or will be * soon. If we don't synchronize here, there is a chance * that this process may msleep() again before the callout * has a chance to run and the callout may end up waking up * the wrong msleep(). Yuck. */ TD_SET_SLEEPING(td); p->p_stats->p_ru.ru_nivcsw++; mi_switch(); td->td_flags &= ~TDF_TIMOFAIL; } if ((td->td_flags & TDF_INTERRUPT) && (priority & PCATCH) && (rval == 0)) { rval = td->td_intrval; } mtx_unlock_spin(&sched_lock); if (rval == 0 && catch) { PROC_LOCK(p); /* XXX: shouldn't we always be calling cursig() */ mtx_lock(&p->p_sigacts->ps_mtx); if (sig != 0 || (sig = cursig(td))) { if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig)) rval = EINTR; else rval = ERESTART; } mtx_unlock(&p->p_sigacts->ps_mtx); PROC_UNLOCK(p); } #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(0, 0); #endif PICKUP_GIANT(); if (mtx != NULL) { mtx_lock(mtx); WITNESS_RESTORE(&mtx->mtx_object, mtx); } return (rval); } /* * Implement timeout for msleep() * * If process hasn't been awakened (wchan non-zero), * set timeout flag and undo the sleep. If proc * is stopped, just unsleep so it will remain stopped. * MP-safe, called without the Giant mutex. */ static void endtsleep(arg) void *arg; { register struct thread *td = arg; CTR3(KTR_PROC, "endtsleep: thread %p (pid %d, %s)", td, td->td_proc->p_pid, td->td_proc->p_comm); mtx_lock_spin(&sched_lock); /* * This is the other half of the synchronization with msleep() * described above. If the TDS_TIMEOUT flag is set, we lost the * race and just need to put the process back on the runqueue. */ if (TD_ON_SLEEPQ(td)) { TAILQ_REMOVE(&slpque[LOOKUP(td->td_wchan)], td, td_slpq); TD_CLR_ON_SLEEPQ(td); td->td_flags |= TDF_TIMEOUT; td->td_wmesg = NULL; } else { td->td_flags |= TDF_TIMOFAIL; } TD_CLR_SLEEPING(td); setrunnable(td); mtx_unlock_spin(&sched_lock); } /* * Abort a thread, as if an interrupt had occured. Only abort * interruptable waits (unfortunatly it isn't only safe to abort others). * This is about identical to cv_abort(). * Think about merging them? * Also, whatever the signal code does... */ void abortsleep(struct thread *td) { mtx_assert(&sched_lock, MA_OWNED); /* * If the TDF_TIMEOUT flag is set, just leave. A * timeout is scheduled anyhow. */ if ((td->td_flags & (TDF_TIMEOUT | TDF_SINTR)) == TDF_SINTR) { if (TD_ON_SLEEPQ(td)) { unsleep(td); TD_CLR_SLEEPING(td); setrunnable(td); } } } /* * Remove a process from its wait queue */ void unsleep(struct thread *td) { mtx_lock_spin(&sched_lock); if (TD_ON_SLEEPQ(td)) { TAILQ_REMOVE(&slpque[LOOKUP(td->td_wchan)], td, td_slpq); TD_CLR_ON_SLEEPQ(td); td->td_wmesg = NULL; } mtx_unlock_spin(&sched_lock); } /* * Make all processes sleeping on the specified identifier runnable. */ void wakeup(ident) register void *ident; { register struct slpquehead *qp; register struct thread *td; struct thread *ntd; struct proc *p; mtx_lock_spin(&sched_lock); qp = &slpque[LOOKUP(ident)]; restart: for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) { ntd = TAILQ_NEXT(td, td_slpq); if (td->td_wchan == ident) { unsleep(td); TD_CLR_SLEEPING(td); setrunnable(td); p = td->td_proc; CTR3(KTR_PROC,"wakeup: thread %p (pid %d, %s)", td, p->p_pid, p->p_comm); goto restart; } } mtx_unlock_spin(&sched_lock); } /* * Make a process sleeping on the specified identifier runnable. * May wake more than one process if a target process is currently * swapped out. */ void wakeup_one(ident) register void *ident; { register struct slpquehead *qp; register struct thread *td; register struct proc *p; struct thread *ntd; mtx_lock_spin(&sched_lock); qp = &slpque[LOOKUP(ident)]; for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) { ntd = TAILQ_NEXT(td, td_slpq); if (td->td_wchan == ident) { unsleep(td); TD_CLR_SLEEPING(td); setrunnable(td); p = td->td_proc; CTR3(KTR_PROC,"wakeup1: thread %p (pid %d, %s)", td, p->p_pid, p->p_comm); break; } } mtx_unlock_spin(&sched_lock); } /* * The machine independent parts of mi_switch(). */ void mi_switch(void) { struct bintime new_switchtime; struct thread *td; #if !defined(__alpha__) && !defined(__powerpc__) struct thread *newtd; #endif struct proc *p; u_int sched_nest; 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, ("mi_switch: switch in a critical section")); /* * 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)); #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); CTR3(KTR_PROC, "mi_switch: old thread %p (pid %d, %s)", td, p->p_pid, p->p_comm); sched_nest = sched_lock.mtx_recurse; if (td->td_proc->p_flag & P_SA) thread_switchout(td); sched_switchout(td); #if !defined(__alpha__) && !defined(__powerpc__) newtd = choosethread(); if (td != newtd) cpu_switch(td, newtd); /* SHAZAM!! */ #else cpu_switch(); /* SHAZAM!!*/ #endif sched_lock.mtx_recurse = sched_nest; sched_lock.mtx_lock = (uintptr_t)td; sched_switchin(td); /* * Start setting up stats etc. for the incoming thread. * Similar code in fork_exit() is returned to by cpu_switch() * in the case of a new thread/process. */ CTR3(KTR_PROC, "mi_switch: new thread %p (pid %d, %s)", td, p->p_pid, p->p_comm); if (PCPU_GET(switchtime.sec) == 0) binuptime(PCPU_PTR(switchtime)); PCPU_SET(switchticks, ticks); /* * Call the switchin function while still holding the scheduler lock * (used by the idlezero code and the general page-zeroing code) */ if (td->td_switchin) td->td_switchin(); /* * 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 = 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; struct proc *p; struct thread *td; avg = &averunnable; sx_slock(&allproc_lock); nrun = 0; FOREACH_PROC_IN_SYSTEM(p) { FOREACH_THREAD_IN_PROC(p, td) { switch (td->td_state) { case TDS_RUNQ: case TDS_RUNNING: if ((p->p_flag & P_NOLOAD) != 0) goto nextproc; nrun++; /* XXXKSE */ default: break; } nextproc: continue; } } sx_sunlock(&allproc_lock); 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 sched_setup(dummy) void *dummy; { callout_init(&loadav_callout, 0); callout_init(&lbolt_callout, 1); /* 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 = td->td_ksegrp; mtx_assert(&Giant, MA_NOTOWNED); mtx_lock_spin(&sched_lock); kg->kg_proc->p_stats->p_ru.ru_nvcsw++; sched_prio(td, PRI_MAX_TIMESHARE); mi_switch(); mtx_unlock_spin(&sched_lock); td->td_retval[0] = 0; return (0); }