freebsd-skq/sys/kern/kern_condvar.c
jake 55d5108ac5 Implement a unified run queue and adjust priority levels accordingly.
- All processes go into the same array of queues, with different
  scheduling classes using different portions of the array.  This
  allows user processes to have their priorities propogated up into
  interrupt thread range if need be.
- I chose 64 run queues as an arbitrary number that is greater than
  32.  We used to have 4 separate arrays of 32 queues each, so this
  may not be optimal.  The new run queue code was written with this
  in mind; changing the number of run queues only requires changing
  constants in runq.h and adjusting the priority levels.
- The new run queue code takes the run queue as a parameter.  This
  is intended to be used to create per-cpu run queues.  Implement
  wrappers for compatibility with the old interface which pass in
  the global run queue structure.
- Group the priority level, user priority, native priority (before
  propogation) and the scheduling class into a struct priority.
- Change any hard coded priority levels that I found to use
  symbolic constants (TTIPRI and TTOPRI).
- Remove the curpriority global variable and use that of curproc.
  This was used to detect when a process' priority had lowered and
  it should yield.  We now effectively yield on every interrupt.
- Activate propogate_priority().  It should now have the desired
  effect without needing to also propogate the scheduling class.
- Temporarily comment out the call to vm_page_zero_idle() in the
  idle loop.  It interfered with propogate_priority() because
  the idle process needed to do a non-blocking acquire of Giant
  and then other processes would try to propogate their priority
  onto it.  The idle process should not do anything except idle.
  vm_page_zero_idle() will return in the form of an idle priority
  kernel thread which is woken up at apprioriate times by the vm
  system.
- Update struct kinfo_proc to the new priority interface.  Deliberately
  change its size by adjusting the spare fields.  It remained the same
  size, but the layout has changed, so userland processes that use it
  would parse the data incorrectly.  The size constraint should really
  be changed to an arbitrary version number.  Also add a debug.sizeof
  sysctl node for struct kinfo_proc.
2001-02-12 00:20:08 +00:00

543 lines
13 KiB
C

/*-
* Copyright (c) 2000 Jake Burkholder <jake@freebsd.org>.
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
#include "opt_ktrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/condvar.h>
#include <sys/mutex.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
#ifdef KTRACE
#include <sys/uio.h>
#include <sys/ktrace.h>
#endif
/*
* Common sanity checks for cv_wait* functions.
*/
#define CV_ASSERT(cvp, mp, p) do { \
KASSERT((p) != NULL, ("%s: curproc NULL", __FUNCTION__)); \
KASSERT((p)->p_stat == SRUN, ("%s: not SRUN", __FUNCTION__)); \
KASSERT((cvp) != NULL, ("%s: cvp NULL", __FUNCTION__)); \
KASSERT((mp) != NULL, ("%s: mp NULL", __FUNCTION__)); \
mtx_assert((mp), MA_OWNED | MA_NOTRECURSED); \
} while (0)
#ifdef CV_DEBUG
#define CV_WAIT_VALIDATE(cvp, mp) do { \
if (TAILQ_EMPTY(&(cvp)->cv_waitq)) { \
/* Only waiter. */ \
(cvp)->cv_mtx = (mp); \
} else { \
/* \
* Other waiter; assert that we're using the \
* same mutex. \
*/ \
KASSERT((cvp)->cv_mtx == (mp), \
("%s: Multiple mutexes", __FUNCTION__)); \
} \
} while (0)
#define CV_SIGNAL_VALIDATE(cvp) do { \
if (!TAILQ_EMPTY(&(cvp)->cv_waitq)) { \
KASSERT(mtx_owned((cvp)->cv_mtx), \
("%s: Mutex not owned", __FUNCTION__)); \
} \
} while (0)
#else
#define CV_WAIT_VALIDATE(cvp, mp)
#define CV_SIGNAL_VALIDATE(cvp)
#endif
static void cv_timedwait_end(void *arg);
/*
* Initialize a condition variable. Must be called before use.
*/
void
cv_init(struct cv *cvp, const char *desc)
{
TAILQ_INIT(&cvp->cv_waitq);
cvp->cv_mtx = NULL;
cvp->cv_description = desc;
}
/*
* Destroy a condition variable. The condition variable must be re-initialized
* in order to be re-used.
*/
void
cv_destroy(struct cv *cvp)
{
KASSERT(cv_waitq_empty(cvp), ("%s: cv_waitq non-empty", __FUNCTION__));
}
/*
* Common code for cv_wait* functions. All require sched_lock.
*/
/*
* Switch context.
*/
static __inline void
cv_switch(struct proc *p)
{
p->p_stat = SSLEEP;
p->p_stats->p_ru.ru_nvcsw++;
mi_switch();
CTR3(KTR_PROC, "cv_switch: resume proc %p (pid %d, %s)", p, p->p_pid,
p->p_comm);
}
/*
* Switch context, catching signals.
*/
static __inline int
cv_switch_catch(struct proc *p)
{
int sig;
/*
* We put ourselves on the sleep queue and start our timeout before
* calling CURSIG, as we could stop there, and a wakeup or a SIGCONT (or
* both) could occur while we were stopped. A SIGCONT would cause us to
* be marked as SSLEEP without resuming us, thus we must be ready for
* sleep when CURSIG is called. If the wakeup happens while we're
* stopped, p->p_wchan will be 0 upon return from CURSIG.
*/
p->p_sflag |= PS_SINTR;
mtx_unlock_spin(&sched_lock);
sig = CURSIG(p);
mtx_lock_spin(&sched_lock);
if (sig != 0) {
if (p->p_wchan != NULL)
cv_waitq_remove(p);
p->p_stat = SRUN;
} else if (p->p_wchan != NULL) {
cv_switch(p);
}
p->p_sflag &= ~PS_SINTR;
return sig;
}
/*
* Add a process to the wait queue of a condition variable.
*/
static __inline void
cv_waitq_add(struct cv *cvp, struct proc *p)
{
/*
* Process may be sitting on a slpque if asleep() was called, remove it
* before re-adding.
*/
if (p->p_wchan != NULL)
unsleep(p);
p->p_sflag |= PS_CVWAITQ;
p->p_wchan = cvp;
p->p_wmesg = cvp->cv_description;
p->p_slptime = 0;
p->p_pri.pri_native = p->p_pri.pri_level;
CTR3(KTR_PROC, "cv_waitq_add: proc %p (pid %d, %s)", p, p->p_pid,
p->p_comm);
TAILQ_INSERT_TAIL(&cvp->cv_waitq, p, p_slpq);
}
/*
* Wait on a condition variable. The current process is placed on the condition
* variable's wait queue and suspended. A cv_signal or cv_broadcast on the same
* condition variable will resume the process. The mutex is released before
* sleeping and will be held on return. It is recommended that the mutex be
* held when cv_signal or cv_broadcast are called.
*/
void
cv_wait(struct cv *cvp, struct mtx *mp)
{
struct proc *p;
WITNESS_SAVE_DECL(mp);
p = CURPROC;
#ifdef KTRACE
if (p && KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 1, 0);
#endif
CV_ASSERT(cvp, mp, p);
WITNESS_SLEEP(0, mp);
WITNESS_SAVE(mp, mp);
mtx_lock_spin(&sched_lock);
if (cold || panicstr) {
/*
* After a panic, or 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.
*/
mtx_unlock_spin(&sched_lock);
return;
}
CV_WAIT_VALIDATE(cvp, mp);
DROP_GIANT_NOSWITCH();
mtx_unlock_flags(mp, MTX_NOSWITCH);
cv_waitq_add(cvp, p);
cv_switch(p);
mtx_unlock_spin(&sched_lock);
#ifdef KTRACE
if (KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 0, 0);
#endif
PICKUP_GIANT();
mtx_lock(mp);
WITNESS_RESTORE(mp, mp);
}
/*
* Wait on a condition variable, allowing interruption by signals. Return 0 if
* the process was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if
* a signal was caught. If ERESTART is returned the system call should be
* restarted if possible.
*/
int
cv_wait_sig(struct cv *cvp, struct mtx *mp)
{
struct proc *p;
int rval;
int sig;
WITNESS_SAVE_DECL(mp);
p = CURPROC;
rval = 0;
#ifdef KTRACE
if (p && KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 1, 0);
#endif
CV_ASSERT(cvp, mp, p);
WITNESS_SLEEP(0, mp);
WITNESS_SAVE(mp, mp);
mtx_lock_spin(&sched_lock);
if (cold || panicstr) {
/*
* After a panic, or 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.
*/
mtx_unlock_spin(&sched_lock);
return 0;
}
CV_WAIT_VALIDATE(cvp, mp);
DROP_GIANT_NOSWITCH();
mtx_unlock_flags(mp, MTX_NOSWITCH);
cv_waitq_add(cvp, p);
sig = cv_switch_catch(p);
mtx_unlock_spin(&sched_lock);
PICKUP_GIANT();
/* proc_lock(p); */
if (sig == 0)
sig = CURSIG(p);
if (sig != 0) {
if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
rval = EINTR;
else
rval = ERESTART;
}
/* proc_unlock(p); */
#ifdef KTRACE
if (KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 0, 0);
#endif
mtx_lock(mp);
WITNESS_RESTORE(mp, mp);
return (rval);
}
/*
* Wait on a condition variable for at most timo/hz seconds. Returns 0 if the
* process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout
* expires.
*/
int
cv_timedwait(struct cv *cvp, struct mtx *mp, int timo)
{
struct proc *p;
int rval;
WITNESS_SAVE_DECL(mp);
p = CURPROC;
rval = 0;
#ifdef KTRACE
if (p && KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 1, 0);
#endif
CV_ASSERT(cvp, mp, p);
WITNESS_SLEEP(0, mp);
WITNESS_SAVE(mp, mp);
mtx_lock_spin(&sched_lock);
if (cold || panicstr) {
/*
* After a panic, or 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.
*/
mtx_unlock_spin(&sched_lock);
return 0;
}
CV_WAIT_VALIDATE(cvp, mp);
DROP_GIANT_NOSWITCH();
mtx_unlock_flags(mp, MTX_NOSWITCH);
cv_waitq_add(cvp, p);
callout_reset(&p->p_slpcallout, timo, cv_timedwait_end, p);
cv_switch(p);
if (p->p_sflag & PS_TIMEOUT) {
p->p_sflag &= ~PS_TIMEOUT;
rval = EWOULDBLOCK;
} else
callout_stop(&p->p_slpcallout);
mtx_unlock_spin(&sched_lock);
#ifdef KTRACE
if (KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 0, 0);
#endif
PICKUP_GIANT();
mtx_lock(mp);
WITNESS_RESTORE(mp, mp);
return (rval);
}
/*
* Wait on a condition variable for at most timo/hz seconds, allowing
* interruption by signals. Returns 0 if the process was resumed by cv_signal
* or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if
* a signal was caught.
*/
int
cv_timedwait_sig(struct cv *cvp, struct mtx *mp, int timo)
{
struct proc *p;
int rval;
int sig;
WITNESS_SAVE_DECL(mp);
p = CURPROC;
rval = 0;
#ifdef KTRACE
if (p && KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 1, 0);
#endif
CV_ASSERT(cvp, mp, p);
WITNESS_SLEEP(0, mp);
WITNESS_SAVE(mp, mp);
mtx_lock_spin(&sched_lock);
if (cold || panicstr) {
/*
* After a panic, or 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.
*/
mtx_unlock_spin(&sched_lock);
return 0;
}
CV_WAIT_VALIDATE(cvp, mp);
DROP_GIANT_NOSWITCH();
mtx_unlock_flags(mp, MTX_NOSWITCH);
cv_waitq_add(cvp, p);
callout_reset(&p->p_slpcallout, timo, cv_timedwait_end, p);
sig = cv_switch_catch(p);
if (p->p_sflag & PS_TIMEOUT) {
p->p_sflag &= ~PS_TIMEOUT;
rval = EWOULDBLOCK;
} else
callout_stop(&p->p_slpcallout);
mtx_unlock_spin(&sched_lock);
PICKUP_GIANT();
/* proc_lock(p); */
if (sig == 0)
sig = CURSIG(p);
if (sig != 0) {
if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
rval = EINTR;
else
rval = ERESTART;
}
/* proc_unlock(p); */
#ifdef KTRACE
if (KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 0, 0);
#endif
mtx_lock(mp);
WITNESS_RESTORE(mp, mp);
return (rval);
}
/*
* Common code for signal and broadcast. Assumes waitq is not empty. Must be
* called with sched_lock held.
*/
static __inline void
cv_wakeup(struct cv *cvp)
{
struct proc *p;
mtx_assert(&sched_lock, MA_OWNED);
p = TAILQ_FIRST(&cvp->cv_waitq);
KASSERT(p->p_wchan == cvp, ("%s: bogus wchan", __FUNCTION__));
KASSERT(p->p_sflag & PS_CVWAITQ, ("%s: not on waitq", __FUNCTION__));
TAILQ_REMOVE(&cvp->cv_waitq, p, p_slpq);
p->p_sflag &= ~PS_CVWAITQ;
p->p_wchan = 0;
if (p->p_stat == SSLEEP) {
/* OPTIMIZED EXPANSION OF setrunnable(p); */
CTR3(KTR_PROC, "cv_signal: proc %p (pid %d, %s)",
p, p->p_pid, p->p_comm);
if (p->p_slptime > 1)
updatepri(p);
p->p_slptime = 0;
p->p_stat = SRUN;
if (p->p_sflag & PS_INMEM) {
setrunqueue(p);
maybe_resched(p);
} else {
p->p_sflag |= PS_SWAPINREQ;
wakeup(&proc0);
}
/* END INLINE EXPANSION */
}
}
/*
* Signal a condition variable, wakes up one waiting process. Will also wakeup
* the swapper if the process is not in memory, so that it can bring the
* sleeping process in. Note that this may also result in additional processes
* being made runnable. Should be called with the same mutex as was passed to
* cv_wait held.
*/
void
cv_signal(struct cv *cvp)
{
KASSERT(cvp != NULL, ("%s: cvp NULL", __FUNCTION__));
mtx_lock_spin(&sched_lock);
if (!TAILQ_EMPTY(&cvp->cv_waitq)) {
CV_SIGNAL_VALIDATE(cvp);
cv_wakeup(cvp);
}
mtx_unlock_spin(&sched_lock);
}
/*
* Broadcast a signal to a condition variable. Wakes up all waiting processes.
* Should be called with the same mutex as was passed to cv_wait held.
*/
void
cv_broadcast(struct cv *cvp)
{
KASSERT(cvp != NULL, ("%s: cvp NULL", __FUNCTION__));
mtx_lock_spin(&sched_lock);
CV_SIGNAL_VALIDATE(cvp);
while (!TAILQ_EMPTY(&cvp->cv_waitq))
cv_wakeup(cvp);
mtx_unlock_spin(&sched_lock);
}
/*
* Remove a process from the wait queue of its condition variable. This may be
* called externally.
*/
void
cv_waitq_remove(struct proc *p)
{
struct cv *cvp;
mtx_lock_spin(&sched_lock);
if ((cvp = p->p_wchan) != NULL && p->p_sflag & PS_CVWAITQ) {
TAILQ_REMOVE(&cvp->cv_waitq, p, p_slpq);
p->p_sflag &= ~PS_CVWAITQ;
p->p_wchan = NULL;
}
mtx_unlock_spin(&sched_lock);
}
/*
* Timeout function for cv_timedwait. Put the process on the runqueue and set
* its timeout flag.
*/
static void
cv_timedwait_end(void *arg)
{
struct proc *p;
p = arg;
CTR3(KTR_PROC, "cv_timedwait_end: proc %p (pid %d, %s)", p, p->p_pid,
p->p_comm);
mtx_lock_spin(&sched_lock);
if (p->p_wchan != NULL) {
if (p->p_stat == SSLEEP)
setrunnable(p);
else
cv_waitq_remove(p);
p->p_sflag |= PS_TIMEOUT;
}
mtx_unlock_spin(&sched_lock);
}