595 lines
16 KiB
C
595 lines
16 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 "opt_sched.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/sdt.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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#define KTDSTATE(td) \
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(((td)->td_inhibitors & TDI_SLEEPING) != 0 ? "sleep" : \
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((td)->td_inhibitors & TDI_SUSPENDED) != 0 ? "suspended" : \
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((td)->td_inhibitors & TDI_SWAPPED) != 0 ? "swapped" : \
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((td)->td_inhibitors & TDI_LOCK) != 0 ? "blocked" : \
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((td)->td_inhibitors & TDI_IWAIT) != 0 ? "iwait" : "yielding")
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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,
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NULL);
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int hogticks;
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static uint8_t pause_wchan[MAXCPU];
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static struct callout loadav_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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SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, FSCALE, "");
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static void loadav(void *arg);
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SDT_PROVIDER_DECLARE(sched);
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SDT_PROBE_DEFINE(sched, , , preempt);
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static void
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sleepinit(void *unused)
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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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* vmem tries to lock the sleepq mutexes when free'ing kva, so make sure
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* it is available.
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*/
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SYSINIT(sleepinit, SI_SUB_KMEM, SI_ORDER_ANY, sleepinit, 0);
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/*
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* General sleep call. Suspends the current thread until a wakeup is
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* performed on the specified identifier. The thread will then be made
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* runnable with the specified priority. Sleeps at most sbt units of time
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* (0 means no timeout). If pri includes the PCATCH flag, let signals
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* interrupt the sleep, otherwise ignore them while sleeping. Returns 0 if
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* awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a
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* signal becomes pending, 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 lock argument is unlocked before the caller is suspended, and
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* re-locked before _sleep() returns. If priority includes the PDROP
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* flag the lock is not re-locked before returning.
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*/
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int
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_sleep(void *ident, struct lock_object *lock, int priority,
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const char *wmesg, sbintime_t sbt, sbintime_t pr, int flags)
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{
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struct thread *td;
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struct proc *p;
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struct lock_class *class;
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uintptr_t lock_state;
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int catch, pri, rval, sleepq_flags;
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WITNESS_SAVE_DECL(lock_witness);
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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, wmesg);
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#endif
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
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"Sleeping on \"%s\"", wmesg);
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KASSERT(sbt != 0 || mtx_owned(&Giant) || lock != NULL,
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("sleeping without a lock"));
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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 (priority & PDROP)
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KASSERT(lock != NULL && lock != &Giant.lock_object,
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("PDROP requires a non-Giant lock"));
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if (lock != NULL)
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class = LOCK_CLASS(lock);
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else
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class = NULL;
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if (SCHEDULER_STOPPED()) {
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if (lock != NULL && priority & PDROP)
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class->lc_unlock(lock);
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return (0);
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}
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catch = priority & PCATCH;
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pri = priority & PRIMASK;
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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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if ((uint8_t *)ident >= &pause_wchan[0] &&
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(uint8_t *)ident <= &pause_wchan[MAXCPU - 1])
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sleepq_flags = SLEEPQ_PAUSE;
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else
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sleepq_flags = SLEEPQ_SLEEP;
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if (catch)
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sleepq_flags |= SLEEPQ_INTERRUPTIBLE;
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sleepq_lock(ident);
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CTR5(KTR_PROC, "sleep: thread %ld (pid %ld, %s) on %s (%p)",
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td->td_tid, p->p_pid, td->td_name, wmesg, ident);
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if (lock == &Giant.lock_object)
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mtx_assert(&Giant, MA_OWNED);
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DROP_GIANT();
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if (lock != NULL && lock != &Giant.lock_object &&
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!(class->lc_flags & LC_SLEEPABLE)) {
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WITNESS_SAVE(lock, lock_witness);
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lock_state = class->lc_unlock(lock);
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} else
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/* GCC needs to follow the Yellow Brick Road */
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lock_state = -1;
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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(ident, lock, wmesg, sleepq_flags, 0);
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if (sbt != 0)
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sleepq_set_timeout_sbt(ident, sbt, pr, flags);
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if (lock != NULL && class->lc_flags & LC_SLEEPABLE) {
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sleepq_release(ident);
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WITNESS_SAVE(lock, lock_witness);
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lock_state = class->lc_unlock(lock);
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sleepq_lock(ident);
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}
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if (sbt != 0 && catch)
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rval = sleepq_timedwait_sig(ident, pri);
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else if (sbt != 0)
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rval = sleepq_timedwait(ident, pri);
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else if (catch)
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rval = sleepq_wait_sig(ident, pri);
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else {
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sleepq_wait(ident, pri);
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rval = 0;
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}
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0, wmesg);
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#endif
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PICKUP_GIANT();
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if (lock != NULL && lock != &Giant.lock_object && !(priority & PDROP)) {
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class->lc_lock(lock, lock_state);
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WITNESS_RESTORE(lock, lock_witness);
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}
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return (rval);
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}
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int
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msleep_spin_sbt(void *ident, struct mtx *mtx, const char *wmesg,
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sbintime_t sbt, sbintime_t pr, int flags)
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{
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struct thread *td;
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struct proc *p;
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int rval;
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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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KASSERT(mtx != NULL, ("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 (SCHEDULER_STOPPED())
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return (0);
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sleepq_lock(ident);
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CTR5(KTR_PROC, "msleep_spin: thread %ld (pid %ld, %s) on %s (%p)",
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td->td_tid, p->p_pid, td->td_name, wmesg, ident);
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DROP_GIANT();
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mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED);
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WITNESS_SAVE(&mtx->lock_object, mtx);
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mtx_unlock_spin(mtx);
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/*
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* We put ourselves on the sleep queue and start our timeout.
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*/
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sleepq_add(ident, &mtx->lock_object, wmesg, SLEEPQ_SLEEP, 0);
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if (sbt != 0)
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sleepq_set_timeout_sbt(ident, sbt, pr, flags);
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/*
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* Can't call ktrace with any spin locks held so it can lock the
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* ktrace_mtx lock, and WITNESS_WARN considers it an error to hold
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* any spin lock. Thus, we have to drop the sleepq spin lock while
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* we handle those requests. This is safe since we have placed our
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* thread on the sleep queue already.
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*/
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW)) {
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sleepq_release(ident);
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ktrcsw(1, 0, wmesg);
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sleepq_lock(ident);
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}
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#endif
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#ifdef WITNESS
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sleepq_release(ident);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "Sleeping on \"%s\"",
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wmesg);
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sleepq_lock(ident);
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#endif
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if (sbt != 0)
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rval = sleepq_timedwait(ident, 0);
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else {
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sleepq_wait(ident, 0);
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rval = 0;
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}
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0, wmesg);
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#endif
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PICKUP_GIANT();
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mtx_lock_spin(mtx);
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WITNESS_RESTORE(&mtx->lock_object, mtx);
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return (rval);
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}
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/*
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* pause() delays the calling thread by the given number of system ticks.
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* During cold bootup, pause() uses the DELAY() function instead of
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* the tsleep() function to do the waiting. The "timo" argument must be
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* greater than or equal to zero. A "timo" value of zero is equivalent
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* to a "timo" value of one.
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*/
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int
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pause_sbt(const char *wmesg, sbintime_t sbt, sbintime_t pr, int flags)
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{
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KASSERT(sbt >= 0, ("pause: timeout must be >= 0"));
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/* silently convert invalid timeouts */
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if (sbt == 0)
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sbt = tick_sbt;
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if (cold || kdb_active || SCHEDULER_STOPPED()) {
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/*
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* We delay one second at a time to avoid overflowing the
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* system specific DELAY() function(s):
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*/
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while (sbt >= SBT_1S) {
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DELAY(1000000);
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sbt -= SBT_1S;
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}
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/* Do the delay remainder, if any */
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sbt = howmany(sbt, SBT_1US);
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if (sbt > 0)
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DELAY(sbt);
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return (0);
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}
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return (_sleep(&pause_wchan[curcpu], NULL, 0, wmesg, sbt, pr, flags));
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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(void *ident)
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{
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int wakeup_swapper;
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sleepq_lock(ident);
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wakeup_swapper = sleepq_broadcast(ident, SLEEPQ_SLEEP, 0, 0);
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sleepq_release(ident);
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if (wakeup_swapper) {
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KASSERT(ident != &proc0,
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("wakeup and wakeup_swapper and proc0"));
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kick_proc0();
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}
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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(void *ident)
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{
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int wakeup_swapper;
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sleepq_lock(ident);
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wakeup_swapper = sleepq_signal(ident, SLEEPQ_SLEEP, 0, 0);
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sleepq_release(ident);
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if (wakeup_swapper)
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kick_proc0();
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}
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static void
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kdb_switch(void)
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{
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thread_unlock(curthread);
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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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* 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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uint64_t runtime, new_switchtime;
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struct thread *td;
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td = curthread; /* XXX */
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THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
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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 || panicstr,
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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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/*
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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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kdb_switch();
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if (SCHEDULER_STOPPED())
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return;
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if (flags & SW_VOL) {
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td->td_ru.ru_nvcsw++;
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td->td_swvoltick = ticks;
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} else {
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td->td_ru.ru_nivcsw++;
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td->td_swinvoltick = ticks;
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}
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#ifdef SCHED_STATS
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SCHED_STAT_INC(sched_switch_stats[flags & SW_TYPE_MASK]);
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#endif
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/*
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* Compute the amount of time during which the current
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* thread was running, and add that to its total so far.
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*/
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new_switchtime = cpu_ticks();
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runtime = new_switchtime - PCPU_GET(switchtime);
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td->td_runtime += runtime;
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td->td_incruntime += runtime;
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PCPU_SET(switchtime, new_switchtime);
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td->td_generation++; /* bump preempt-detect counter */
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PCPU_INC(cnt.v_swtch);
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PCPU_SET(switchticks, ticks);
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CTR4(KTR_PROC, "mi_switch: old thread %ld (td_sched %p, pid %ld, %s)",
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td->td_tid, td_get_sched(td), td->td_proc->p_pid, td->td_name);
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#if (KTR_COMPILE & KTR_SCHED) != 0
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if (TD_IS_IDLETHREAD(td))
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KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle",
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"prio:%d", td->td_priority);
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else
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KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td),
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"prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg,
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"lockname:\"%s\"", td->td_lockname);
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#endif
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SDT_PROBE0(sched, , , preempt);
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sched_switch(td, newtd, flags);
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KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
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"prio:%d", td->td_priority);
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CTR4(KTR_PROC, "mi_switch: new thread %ld (td_sched %p, pid %ld, %s)",
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td->td_tid, td_get_sched(td), td->td_proc->p_pid, td->td_name);
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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 thread state to be runnable, placing it on the run queue if
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* it is in memory. If it is swapped out, return true so our caller
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* will know to awaken the swapper.
|
|
*/
|
|
int
|
|
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 (0);
|
|
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 (0);
|
|
/* FALLTHROUGH */
|
|
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;
|
|
return (1);
|
|
}
|
|
} else
|
|
sched_wakeup(td);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* 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_sbt(&loadav_callout,
|
|
SBT_1US * (4000000 + (int)(random() % 2000001)), SBT_1US,
|
|
loadav, NULL, C_DIRECT_EXEC | C_PREL(32));
|
|
}
|
|
|
|
/* ARGSUSED */
|
|
static void
|
|
synch_setup(void *dummy)
|
|
{
|
|
callout_init(&loadav_callout, 1);
|
|
|
|
/* Kick off timeout driven events by calling first time. */
|
|
loadav(NULL);
|
|
}
|
|
|
|
int
|
|
should_yield(void)
|
|
{
|
|
|
|
return ((u_int)ticks - (u_int)curthread->td_swvoltick >= hogticks);
|
|
}
|
|
|
|
void
|
|
maybe_yield(void)
|
|
{
|
|
|
|
if (should_yield())
|
|
kern_yield(PRI_USER);
|
|
}
|
|
|
|
void
|
|
kern_yield(int prio)
|
|
{
|
|
struct thread *td;
|
|
|
|
td = curthread;
|
|
DROP_GIANT();
|
|
thread_lock(td);
|
|
if (prio == PRI_USER)
|
|
prio = td->td_user_pri;
|
|
if (prio >= 0)
|
|
sched_prio(td, prio);
|
|
mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
|
|
thread_unlock(td);
|
|
PICKUP_GIANT();
|
|
}
|
|
|
|
/*
|
|
* General purpose yield system call.
|
|
*/
|
|
int
|
|
sys_yield(struct thread *td, struct yield_args *uap)
|
|
{
|
|
|
|
thread_lock(td);
|
|
if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
|
|
sched_prio(td, PRI_MAX_TIMESHARE);
|
|
mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
|
|
thread_unlock(td);
|
|
td->td_retval[0] = 0;
|
|
return (0);
|
|
}
|