freebsd-dev/sys/kern/kern_synch.c
Jeff Roberson 8df78c41d6 - Make SCHED_STATS more generic by adding a wrapper to create the
variables and sysctl nodes.
 - In reset walk the children of kern_sched_stats and reset the counters
   via the oid_arg1 pointer.  This allows us to add arbitrary counters to
   the tree and still reset them properly.
 - Define a set of switch types to be passed with flags to mi_switch().
   These types are named SWT_*.  These types correspond to SCHED_STATS
   counters and are automatically handled in this way.
 - Make the new SWT_ types more specific than the older switch stats.
   There are now stats for idle switches, remote idle wakeups, remote
   preemption ithreads idling, etc.
 - Add switch statistics for ULE's pickcpu algorithm.  These stats include
   how much migration there is, how often affinity was successful, how
   often threads were migrated to the local cpu on wakeup, etc.

Sponsored by:	Nokia
2008-04-17 04:20:10 +00:00

545 lines
15 KiB
C

/*-
* 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ktrace.h"
#include "opt_sched.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/condvar.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/signalvar.h>
#include <sys/sleepqueue.h>
#include <sys/smp.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/vmmeter.h>
#ifdef KTRACE
#include <sys/uio.h>
#include <sys/ktrace.h>
#endif
#include <machine/cpu.h>
static void synch_setup(void *dummy);
SYSINIT(synch_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, synch_setup,
NULL);
int hogticks;
int lbolt;
static int pause_wchan;
static struct callout loadav_callout;
static struct callout lbolt_callout;
struct loadavg averunnable =
{ {0, 0, 0}, FSCALE }; /* load average, of runnable procs */
/*
* Constants for averages over 1, 5, and 15 minutes
* when sampling at 5 second intervals.
*/
static fixpt_t cexp[3] = {
0.9200444146293232 * FSCALE, /* exp(-1/12) */
0.9834714538216174 * FSCALE, /* exp(-1/60) */
0.9944598480048967 * FSCALE, /* exp(-1/180) */
};
/* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */
static int fscale __unused = FSCALE;
SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, "");
static void loadav(void *arg);
static void lboltcb(void *arg);
void
sleepinit(void)
{
hogticks = (hz / 10) * 2; /* Default only. */
init_sleepqueues();
}
/*
* General sleep call. Suspends the current thread until a wakeup is
* performed on the specified identifier. The thread will then be made
* runnable with the specified priority. Sleeps at most timo/hz seconds
* (0 means no timeout). If pri includes PCATCH flag, signals are checked
* before and after sleeping, else signals are not checked. Returns 0 if
* awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a
* signal needs to be delivered, ERESTART is returned if the current system
* call should be restarted if possible, and EINTR is returned if the system
* call should be interrupted by the signal (return EINTR).
*
* The lock argument is unlocked before the caller is suspended, and
* re-locked before _sleep() returns. If priority includes the PDROP
* flag the lock is not re-locked before returning.
*/
int
_sleep(void *ident, struct lock_object *lock, int priority,
const char *wmesg, int timo)
{
struct thread *td;
struct proc *p;
struct lock_class *class;
int catch, flags, lock_state, pri, rval;
WITNESS_SAVE_DECL(lock_witness);
td = curthread;
p = td->td_proc;
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(1, 0);
#endif
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
"Sleeping on \"%s\"", wmesg);
KASSERT(timo != 0 || mtx_owned(&Giant) || lock != NULL ||
ident == &lbolt, ("sleeping without a lock"));
KASSERT(p != NULL, ("msleep1"));
KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep"));
if (lock != NULL)
class = LOCK_CLASS(lock);
else
class = NULL;
if (cold) {
/*
* During autoconfiguration, just return;
* don't run any other threads or panic below,
* in case this is the idle thread and already asleep.
* XXX: this used to do "s = splhigh(); splx(safepri);
* splx(s);" to give interrupts a chance, but there is
* no way to give interrupts a chance now.
*/
if (lock != NULL && priority & PDROP)
class->lc_unlock(lock);
return (0);
}
catch = priority & PCATCH;
pri = priority & PRIMASK;
rval = 0;
/*
* If we are already on a sleep queue, then remove us from that
* sleep queue first. We have to do this to handle recursive
* sleeps.
*/
if (TD_ON_SLEEPQ(td))
sleepq_remove(td, td->td_wchan);
if (ident == &pause_wchan)
flags = SLEEPQ_PAUSE;
else
flags = SLEEPQ_SLEEP;
if (catch)
flags |= SLEEPQ_INTERRUPTIBLE;
sleepq_lock(ident);
CTR5(KTR_PROC, "sleep: thread %ld (pid %ld, %s) on %s (%p)",
td->td_tid, p->p_pid, td->td_name, wmesg, ident);
DROP_GIANT();
if (lock != NULL && !(class->lc_flags & LC_SLEEPABLE)) {
WITNESS_SAVE(lock, lock_witness);
lock_state = class->lc_unlock(lock);
} else
/* GCC needs to follow the Yellow Brick Road */
lock_state = -1;
/*
* We put ourselves on the sleep queue and start our timeout
* before calling thread_suspend_check, as we could stop there,
* and a wakeup or a SIGCONT (or both) could occur while we were
* stopped without resuming us. Thus, we must be ready for sleep
* when cursig() is called. If the wakeup happens while we're
* stopped, then td will no longer be on a sleep queue upon
* return from cursig().
*/
sleepq_add(ident, ident == &lbolt ? NULL : lock, wmesg, flags, 0);
if (timo)
sleepq_set_timeout(ident, timo);
if (lock != NULL && class->lc_flags & LC_SLEEPABLE) {
sleepq_release(ident);
WITNESS_SAVE(lock, lock_witness);
lock_state = class->lc_unlock(lock);
sleepq_lock(ident);
}
if (timo && catch)
rval = sleepq_timedwait_sig(ident, pri);
else if (timo)
rval = sleepq_timedwait(ident, pri);
else if (catch)
rval = sleepq_wait_sig(ident, pri);
else {
sleepq_wait(ident, pri);
rval = 0;
}
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(0, 0);
#endif
PICKUP_GIANT();
if (lock != NULL && !(priority & PDROP)) {
class->lc_lock(lock, lock_state);
WITNESS_RESTORE(lock, lock_witness);
}
return (rval);
}
int
msleep_spin(void *ident, struct mtx *mtx, const char *wmesg, int timo)
{
struct thread *td;
struct proc *p;
int rval;
WITNESS_SAVE_DECL(mtx);
td = curthread;
p = td->td_proc;
KASSERT(mtx != NULL, ("sleeping without a mutex"));
KASSERT(p != NULL, ("msleep1"));
KASSERT(ident != NULL && TD_IS_RUNNING(td), ("msleep"));
if (cold) {
/*
* During autoconfiguration, just return;
* don't run any other threads or panic below,
* in case this is the idle thread and already asleep.
* XXX: this used to do "s = splhigh(); splx(safepri);
* splx(s);" to give interrupts a chance, but there is
* no way to give interrupts a chance now.
*/
return (0);
}
sleepq_lock(ident);
CTR5(KTR_PROC, "msleep_spin: thread %ld (pid %ld, %s) on %s (%p)",
td->td_tid, p->p_pid, td->td_name, wmesg, ident);
DROP_GIANT();
mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED);
WITNESS_SAVE(&mtx->lock_object, mtx);
mtx_unlock_spin(mtx);
/*
* We put ourselves on the sleep queue and start our timeout.
*/
sleepq_add(ident, &mtx->lock_object, wmesg, SLEEPQ_SLEEP, 0);
if (timo)
sleepq_set_timeout(ident, timo);
/*
* Can't call ktrace with any spin locks held so it can lock the
* ktrace_mtx lock, and WITNESS_WARN considers it an error to hold
* any spin lock. Thus, we have to drop the sleepq spin lock while
* we handle those requests. This is safe since we have placed our
* thread on the sleep queue already.
*/
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW)) {
sleepq_release(ident);
ktrcsw(1, 0);
sleepq_lock(ident);
}
#endif
#ifdef WITNESS
sleepq_release(ident);
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "Sleeping on \"%s\"",
wmesg);
sleepq_lock(ident);
#endif
if (timo)
rval = sleepq_timedwait(ident, 0);
else {
sleepq_wait(ident, 0);
rval = 0;
}
#ifdef KTRACE
if (KTRPOINT(td, KTR_CSW))
ktrcsw(0, 0);
#endif
PICKUP_GIANT();
mtx_lock_spin(mtx);
WITNESS_RESTORE(&mtx->lock_object, mtx);
return (rval);
}
/*
* pause() is like tsleep() except that the intention is to not be
* explicitly woken up by another thread. Instead, the current thread
* simply wishes to sleep until the timeout expires. It is
* implemented using a dummy wait channel.
*/
int
pause(const char *wmesg, int timo)
{
KASSERT(timo != 0, ("pause: timeout required"));
return (tsleep(&pause_wchan, 0, wmesg, timo));
}
/*
* Make all threads sleeping on the specified identifier runnable.
*/
void
wakeup(void *ident)
{
sleepq_lock(ident);
sleepq_broadcast(ident, SLEEPQ_SLEEP, 0, 0);
sleepq_release(ident);
}
/*
* Make a thread sleeping on the specified identifier runnable.
* May wake more than one thread if a target thread is currently
* swapped out.
*/
void
wakeup_one(void *ident)
{
sleepq_lock(ident);
sleepq_signal(ident, SLEEPQ_SLEEP, 0, 0);
sleepq_release(ident);
}
static void
kdb_switch(void)
{
thread_unlock(curthread);
kdb_backtrace();
kdb_reenter();
panic("%s: did not reenter debugger", __func__);
}
/*
* The machine independent parts of context switching.
*/
void
mi_switch(int flags, struct thread *newtd)
{
uint64_t runtime, new_switchtime;
struct thread *td;
struct proc *p;
td = curthread; /* XXX */
THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
p = td->td_proc; /* XXX */
KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code"));
#ifdef INVARIANTS
if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td))
mtx_assert(&Giant, MA_NOTOWNED);
#endif
KASSERT(td->td_critnest == 1 || (td->td_critnest == 2 &&
(td->td_owepreempt) && (flags & SW_INVOL) != 0 &&
newtd == NULL) || panicstr,
("mi_switch: switch in a critical section"));
KASSERT((flags & (SW_INVOL | SW_VOL)) != 0,
("mi_switch: switch must be voluntary or involuntary"));
KASSERT(newtd != curthread, ("mi_switch: preempting back to ourself"));
/*
* Don't perform context switches from the debugger.
*/
if (kdb_active)
kdb_switch();
if (flags & SW_VOL)
td->td_ru.ru_nvcsw++;
else
td->td_ru.ru_nivcsw++;
#ifdef SCHED_STATS
SCHED_STAT_INC(sched_switch_stats[flags & SW_TYPE_MASK]);
#endif
/*
* Compute the amount of time during which the current
* thread was running, and add that to its total so far.
*/
new_switchtime = cpu_ticks();
runtime = new_switchtime - PCPU_GET(switchtime);
td->td_runtime += runtime;
td->td_incruntime += runtime;
PCPU_SET(switchtime, new_switchtime);
td->td_generation++; /* bump preempt-detect counter */
PCPU_INC(cnt.v_swtch);
PCPU_SET(switchticks, ticks);
CTR4(KTR_PROC, "mi_switch: old thread %ld (td_sched %p, pid %ld, %s)",
td->td_tid, td->td_sched, p->p_pid, td->td_name);
#if (KTR_COMPILE & KTR_SCHED) != 0
if (TD_IS_IDLETHREAD(td))
CTR3(KTR_SCHED, "mi_switch: %p(%s) prio %d idle",
td, td->td_name, td->td_priority);
else if (newtd != NULL)
CTR5(KTR_SCHED,
"mi_switch: %p(%s) prio %d preempted by %p(%s)",
td, td->td_name, td->td_priority, newtd,
newtd->td_name);
else
CTR6(KTR_SCHED,
"mi_switch: %p(%s) prio %d inhibit %d wmesg %s lock %s",
td, td->td_name, td->td_priority,
td->td_inhibitors, td->td_wmesg, td->td_lockname);
#endif
sched_switch(td, newtd, flags);
CTR3(KTR_SCHED, "mi_switch: running %p(%s) prio %d",
td, td->td_name, td->td_priority);
CTR4(KTR_PROC, "mi_switch: new thread %ld (td_sched %p, pid %ld, %s)",
td->td_tid, td->td_sched, p->p_pid, td->td_name);
/*
* If the last thread was exiting, finish cleaning it up.
*/
if ((td = PCPU_GET(deadthread))) {
PCPU_SET(deadthread, NULL);
thread_stash(td);
}
}
/*
* Change process state to be runnable,
* placing it on the run queue if it is in memory,
* and awakening the swapper if it isn't in memory.
*/
void
setrunnable(struct thread *td)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
KASSERT(td->td_proc->p_state != PRS_ZOMBIE,
("setrunnable: pid %d is a zombie", td->td_proc->p_pid));
switch (td->td_state) {
case TDS_RUNNING:
case TDS_RUNQ:
return;
case TDS_INHIBITED:
/*
* If we are only inhibited because we are swapped out
* then arange to swap in this process. Otherwise just return.
*/
if (td->td_inhibitors != TDI_SWAPPED)
return;
/* XXX: intentional fall-through ? */
case TDS_CAN_RUN:
break;
default:
printf("state is 0x%x", td->td_state);
panic("setrunnable(2)");
}
if ((td->td_flags & TDF_INMEM) == 0) {
if ((td->td_flags & TDF_SWAPINREQ) == 0) {
td->td_flags |= TDF_SWAPINREQ;
/*
* due to a LOR between the thread lock and
* the sleepqueue chain locks, use
* lower level scheduling functions.
*/
kick_proc0();
}
} else
sched_wakeup(td);
}
/*
* Compute a tenex style load average of a quantity on
* 1, 5 and 15 minute intervals.
*/
static void
loadav(void *arg)
{
int i, nrun;
struct loadavg *avg;
nrun = sched_load();
avg = &averunnable;
for (i = 0; i < 3; i++)
avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
/*
* Schedule the next update to occur after 5 seconds, but add a
* random variation to avoid synchronisation with processes that
* run at regular intervals.
*/
callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)),
loadav, NULL);
}
static void
lboltcb(void *arg)
{
wakeup(&lbolt);
callout_reset(&lbolt_callout, hz, lboltcb, NULL);
}
/* ARGSUSED */
static void
synch_setup(void *dummy)
{
callout_init(&loadav_callout, CALLOUT_MPSAFE);
callout_init(&lbolt_callout, CALLOUT_MPSAFE);
/* Kick off timeout driven events by calling first time. */
loadav(NULL);
lboltcb(NULL);
}
/*
* General purpose yield system call.
*/
int
yield(struct thread *td, struct yield_args *uap)
{
thread_lock(td);
sched_prio(td, PRI_MAX_TIMESHARE);
mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
thread_unlock(td);
td->td_retval[0] = 0;
return (0);
}