476 lines
13 KiB
C
476 lines
13 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1990, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)kern_synch.c 8.9 (Berkeley) 5/19/95
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_ktrace.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/condvar.h>
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#include <sys/kdb.h>
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#include <sys/kernel.h>
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#include <sys/ktr.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/resourcevar.h>
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#include <sys/sched.h>
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#include <sys/signalvar.h>
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#include <sys/sleepqueue.h>
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#include <sys/smp.h>
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#include <sys/sx.h>
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#include <sys/sysctl.h>
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#include <sys/sysproto.h>
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#include <sys/vmmeter.h>
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#ifdef KTRACE
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#include <sys/uio.h>
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#include <sys/ktrace.h>
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#endif
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#include <machine/cpu.h>
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static void synch_setup(void *dummy);
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SYSINIT(synch_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, synch_setup, NULL)
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int hogticks;
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int lbolt;
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static struct callout loadav_callout;
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static struct callout lbolt_callout;
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struct loadavg averunnable =
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{ {0, 0, 0}, FSCALE }; /* load average, of runnable procs */
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/*
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* Constants for averages over 1, 5, and 15 minutes
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* when sampling at 5 second intervals.
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*/
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static fixpt_t cexp[3] = {
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0.9200444146293232 * FSCALE, /* exp(-1/12) */
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0.9834714538216174 * FSCALE, /* exp(-1/60) */
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0.9944598480048967 * FSCALE, /* exp(-1/180) */
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};
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/* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */
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static int fscale __unused = FSCALE;
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SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, "");
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static void loadav(void *arg);
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static void lboltcb(void *arg);
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void
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sleepinit(void)
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{
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hogticks = (hz / 10) * 2; /* Default only. */
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init_sleepqueues();
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}
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/*
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* General sleep call. Suspends the current process until a wakeup is
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* performed on the specified identifier. The process will then be made
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* runnable with the specified priority. Sleeps at most timo/hz seconds
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* (0 means no timeout). If pri includes PCATCH flag, signals are checked
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* before and after sleeping, else signals are not checked. Returns 0 if
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* awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a
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* signal needs to be delivered, ERESTART is returned if the current system
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* call should be restarted if possible, and EINTR is returned if the system
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* call should be interrupted by the signal (return EINTR).
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*
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* The mutex argument is exited before the caller is suspended, and
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* entered before msleep returns. If priority includes the PDROP
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* flag the mutex is not entered before returning.
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*/
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int
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msleep(ident, mtx, priority, wmesg, timo)
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void *ident;
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struct mtx *mtx;
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int priority, timo;
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const char *wmesg;
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{
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struct sleepqueue *sq;
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struct thread *td;
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struct proc *p;
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int catch, rval, sig;
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WITNESS_SAVE_DECL(mtx);
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td = curthread;
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p = td->td_proc;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 0);
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#endif
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, mtx == NULL ? NULL :
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&mtx->mtx_object, "Sleeping on \"%s\"", wmesg);
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KASSERT(timo != 0 || mtx_owned(&Giant) || mtx != NULL,
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("sleeping without a mutex"));
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KASSERT(p != NULL, ("msleep1"));
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KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep"));
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if (cold) {
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/*
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* During autoconfiguration, just return;
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* don't run any other threads or panic below,
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* in case this is the idle thread and already asleep.
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* XXX: this used to do "s = splhigh(); splx(safepri);
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* splx(s);" to give interrupts a chance, but there is
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* no way to give interrupts a chance now.
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*/
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if (mtx != NULL && priority & PDROP)
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mtx_unlock(mtx);
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return (0);
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}
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catch = priority & PCATCH;
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rval = 0;
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/*
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* If we are already on a sleep queue, then remove us from that
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* sleep queue first. We have to do this to handle recursive
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* sleeps.
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*/
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if (TD_ON_SLEEPQ(td))
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sleepq_remove(td, td->td_wchan);
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sq = sleepq_lookup(ident);
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mtx_lock_spin(&sched_lock);
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if (p->p_flag & P_SA || p->p_numthreads > 1) {
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/*
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* Just don't bother if we are exiting
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* and not the exiting thread or thread was marked as
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* interrupted.
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*/
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if (catch) {
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if ((p->p_flag & P_SINGLE_EXIT) && p->p_singlethread != td) {
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mtx_unlock_spin(&sched_lock);
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sleepq_release(ident);
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return (EINTR);
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}
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if (td->td_flags & TDF_INTERRUPT) {
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mtx_unlock_spin(&sched_lock);
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sleepq_release(ident);
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return (td->td_intrval);
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}
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}
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}
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mtx_unlock_spin(&sched_lock);
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CTR5(KTR_PROC, "msleep: thread %p (pid %ld, %s) on %s (%p)",
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(void *)td, (long)p->p_pid, p->p_comm, wmesg, ident);
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DROP_GIANT();
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if (mtx != NULL) {
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mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED);
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WITNESS_SAVE(&mtx->mtx_object, mtx);
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mtx_unlock(mtx);
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}
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/*
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* We put ourselves on the sleep queue and start our timeout
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* before calling thread_suspend_check, as we could stop there,
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* and a wakeup or a SIGCONT (or both) could occur while we were
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* stopped without resuming us. Thus, we must be ready for sleep
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* when cursig() is called. If the wakeup happens while we're
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* stopped, then td will no longer be on a sleep queue upon
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* return from cursig().
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*/
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sleepq_add(sq, ident, mtx, wmesg, 0);
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if (timo)
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sleepq_set_timeout(ident, timo);
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if (catch) {
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sig = sleepq_catch_signals(ident);
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if (sig == 0 && !TD_ON_SLEEPQ(td)) {
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mtx_lock_spin(&sched_lock);
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td->td_flags &= ~TDF_SINTR;
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mtx_unlock_spin(&sched_lock);
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catch = 0;
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}
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} else
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sig = 0;
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/*
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* Adjust this thread's priority.
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*
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* XXX: do we need to save priority in td_base_pri?
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*/
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mtx_lock_spin(&sched_lock);
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sched_prio(td, priority & PRIMASK);
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mtx_unlock_spin(&sched_lock);
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if (timo && catch)
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rval = sleepq_timedwait_sig(ident, sig != 0);
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else if (timo)
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rval = sleepq_timedwait(ident);
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else if (catch)
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rval = sleepq_wait_sig(ident);
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else {
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sleepq_wait(ident);
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rval = 0;
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}
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if (rval == 0 && catch)
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rval = sleepq_calc_signal_retval(sig);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0);
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#endif
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PICKUP_GIANT();
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if (mtx != NULL && !(priority & PDROP)) {
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mtx_lock(mtx);
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WITNESS_RESTORE(&mtx->mtx_object, mtx);
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}
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return (rval);
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}
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/*
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* Make all threads sleeping on the specified identifier runnable.
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*/
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void
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wakeup(ident)
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register void *ident;
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{
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sleepq_broadcast(ident, 0, -1);
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}
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/*
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* Make a thread sleeping on the specified identifier runnable.
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* May wake more than one thread if a target thread is currently
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* swapped out.
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*/
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void
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wakeup_one(ident)
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register void *ident;
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{
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sleepq_signal(ident, 0, -1);
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}
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/*
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* The machine independent parts of context switching.
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*/
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void
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mi_switch(int flags, struct thread *newtd)
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{
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struct bintime new_switchtime;
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struct thread *td;
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struct proc *p;
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mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED);
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td = curthread; /* XXX */
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p = td->td_proc; /* XXX */
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KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code"));
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#ifdef INVARIANTS
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if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td))
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mtx_assert(&Giant, MA_NOTOWNED);
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#endif
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KASSERT(td->td_critnest == 1 || (td->td_critnest == 2 &&
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(td->td_pflags & TDP_OWEPREEMPT) != 0 && (flags & SW_INVOL) != 0 &&
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newtd == NULL),
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("mi_switch: switch in a critical section"));
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KASSERT((flags & (SW_INVOL | SW_VOL)) != 0,
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("mi_switch: switch must be voluntary or involuntary"));
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KASSERT(newtd != curthread, ("mi_switch: preempting back to ourself"));
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if (flags & SW_VOL)
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p->p_stats->p_ru.ru_nvcsw++;
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else
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p->p_stats->p_ru.ru_nivcsw++;
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/*
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* Compute the amount of time during which the current
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* process was running, and add that to its total so far.
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*/
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binuptime(&new_switchtime);
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bintime_add(&p->p_runtime, &new_switchtime);
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bintime_sub(&p->p_runtime, PCPU_PTR(switchtime));
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td->td_generation++; /* bump preempt-detect counter */
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/*
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* Don't perform context switches from the debugger.
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*/
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if (kdb_active) {
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mtx_unlock_spin(&sched_lock);
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kdb_backtrace();
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kdb_reenter();
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panic("%s: did not reenter debugger", __func__);
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}
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/*
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* Check if the process exceeds its cpu resource allocation. If
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* over max, arrange to kill the process in ast().
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*/
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if (p->p_cpulimit != RLIM_INFINITY &&
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p->p_runtime.sec > p->p_cpulimit) {
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p->p_sflag |= PS_XCPU;
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td->td_flags |= TDF_ASTPENDING;
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}
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/*
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* Finish up stats for outgoing thread.
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*/
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cnt.v_swtch++;
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PCPU_SET(switchtime, new_switchtime);
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PCPU_SET(switchticks, ticks);
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CTR3(KTR_PROC, "mi_switch: old thread %p (pid %ld, %s)",
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(void *)td, (long)p->p_pid, p->p_comm);
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if (td->td_proc->p_flag & P_SA)
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thread_switchout(td);
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sched_switch(td, newtd);
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CTR3(KTR_PROC, "mi_switch: new thread %p (pid %ld, %s)",
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(void *)td, (long)p->p_pid, p->p_comm);
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/*
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* If the last thread was exiting, finish cleaning it up.
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*/
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if ((td = PCPU_GET(deadthread))) {
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PCPU_SET(deadthread, NULL);
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thread_stash(td);
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}
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}
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/*
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* Change process state to be runnable,
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* placing it on the run queue if it is in memory,
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* and awakening the swapper if it isn't in memory.
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*/
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void
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setrunnable(struct thread *td)
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{
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struct proc *p;
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p = td->td_proc;
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mtx_assert(&sched_lock, MA_OWNED);
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switch (p->p_state) {
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case PRS_ZOMBIE:
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panic("setrunnable(1)");
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default:
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break;
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}
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switch (td->td_state) {
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case TDS_RUNNING:
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case TDS_RUNQ:
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return;
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case TDS_INHIBITED:
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/*
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* If we are only inhibited because we are swapped out
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* then arange to swap in this process. Otherwise just return.
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*/
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if (td->td_inhibitors != TDI_SWAPPED)
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return;
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/* XXX: intentional fall-through ? */
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case TDS_CAN_RUN:
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break;
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default:
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printf("state is 0x%x", td->td_state);
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panic("setrunnable(2)");
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}
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if ((p->p_sflag & PS_INMEM) == 0) {
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if ((p->p_sflag & PS_SWAPPINGIN) == 0) {
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p->p_sflag |= PS_SWAPINREQ;
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wakeup(&proc0);
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}
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} else
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sched_wakeup(td);
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}
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/*
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* Compute a tenex style load average of a quantity on
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* 1, 5 and 15 minute intervals.
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* XXXKSE Needs complete rewrite when correct info is available.
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* Completely Bogus.. only works with 1:1 (but compiles ok now :-)
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*/
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static void
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loadav(void *arg)
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{
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int i, nrun;
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struct loadavg *avg;
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nrun = sched_load();
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avg = &averunnable;
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for (i = 0; i < 3; i++)
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avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
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nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
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/*
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* Schedule the next update to occur after 5 seconds, but add a
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* random variation to avoid synchronisation with processes that
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* run at regular intervals.
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*/
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callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)),
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loadav, NULL);
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}
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static void
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lboltcb(void *arg)
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{
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wakeup(&lbolt);
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callout_reset(&lbolt_callout, hz, lboltcb, NULL);
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}
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/* ARGSUSED */
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static void
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synch_setup(dummy)
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void *dummy;
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{
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callout_init(&loadav_callout, CALLOUT_MPSAFE);
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callout_init(&lbolt_callout, CALLOUT_MPSAFE);
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/* Kick off timeout driven events by calling first time. */
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loadav(NULL);
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lboltcb(NULL);
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}
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/*
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* General purpose yield system call
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*/
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int
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yield(struct thread *td, struct yield_args *uap)
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{
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struct ksegrp *kg;
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kg = td->td_ksegrp;
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mtx_assert(&Giant, MA_NOTOWNED);
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mtx_lock_spin(&sched_lock);
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sched_prio(td, PRI_MAX_TIMESHARE);
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mi_switch(SW_VOL, NULL);
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mtx_unlock_spin(&sched_lock);
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td->td_retval[0] = 0;
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return (0);
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}
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