d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Implement mwakeup, mwakeup_one, cv_signal_drop and cv_broadcast_drop.

Browse Source 
These take an additional mutex argument, which is dropped before any
processes are made runnable.  This can avoid contention on the mutex
if the processes would immediately acquire it, and is done in such a
way that wakeups will not be lost.

Reviewed by:	jhb
This commit is contained in:
jake 2001-07-04 00:32:50 +00:00
parent 0deba2c342
commit 33e85623fa
4 changed files with 58 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
sys/kern/kern_condvar.c
View File

@ -491,6 +491,26 @@ cv_signal(struct cv *cvp)
mtx_unlock_spin(&sched_lock);
}
/*
* Signal a condition variable, dropping the passed in mutex before waking
* a waiting process.
*/
void
cv_signal_drop(struct cv *cvp, struct mtx *mp)
{
KASSERT(cvp != NULL, ("%s: cvp NULL", __FUNCTION__));
KASSERT(mp != NULL, ("%s: mp NULL", __FUNCTION__));
mtx_assert(mp, MA_OWNED | MA_NOTRECURSED);
mtx_lock_spin(&sched_lock);
mtx_unlock_flags(mp, MTX_NOSWITCH);
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.
@ -507,6 +527,25 @@ cv_broadcast(struct cv *cvp)
mtx_unlock_spin(&sched_lock);
}
/*
* Broadcast a signal to a condition variable, dropping the passed in mutex
* before waking any waiting processes.
*/
void
cv_broadcast_drop(struct cv *cvp, struct mtx *mp)
{
KASSERT(cvp != NULL, ("%s: cvp NULL", __FUNCTION__));
KASSERT(mp != NULL, ("%s: mp NULL", __FUNCTION__));
mtx_assert(mp, MA_OWNED | MA_NOTRECURSED);
mtx_lock_spin(&sched_lock);
mtx_unlock_flags(mp, MTX_NOSWITCH);
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.

17
sys/kern/kern_synch.c
View File

@ -709,16 +709,21 @@ unsleep(p)
}
/*
* Make all processes sleeping on the specified identifier runnable.
* Make all processes sleeping on the specified identifier runnable. If
* non-NULL, the specified mutex is dropped before any processes are made
* runnable.
*/
void
wakeup(ident)
mwakeup(ident, mtx)
register void *ident;
register struct mtx *mtx;
{
register struct slpquehead *qp;
register struct proc *p;
mtx_lock_spin(&sched_lock);
if (mtx != NULL)
mtx_unlock_flags(mtx, MTX_NOSWITCH);
qp = &slpque[LOOKUP(ident)];
restart:
TAILQ_FOREACH(p, qp, p_slpq) {
@ -751,16 +756,20 @@ wakeup(ident)
/*
* Make a process sleeping on the specified identifier runnable.
* May wake more than one process if a target process is currently
* swapped out.
* swapped out. If non-NULL, the specified mutex is dropped before
* a process is made runnable.
*/
void
wakeup_one(ident)
mwakeup_one(ident, mtx)
register void *ident;
register struct mtx *mtx;
{
register struct slpquehead *qp;
register struct proc *p;
mtx_lock_spin(&sched_lock);
if (mtx != NULL)
mtx_unlock_flags(mtx, MTX_NOSWITCH);
qp = &slpque[LOOKUP(ident)];
TAILQ_FOREACH(p, qp, p_slpq) {

2
sys/sys/condvar.h
View File

@ -59,7 +59,9 @@ int cv_timedwait(struct cv *cvp, struct mtx *mp, int timo);
int cv_timedwait_sig(struct cv *cvp, struct mtx *mp, int timo);
void cv_signal(struct cv *cvp);
void cv_signal_drop(struct cv *cvp, struct mtx *mp);
void cv_broadcast(struct cv *cvp);
void cv_broadcast_drop(struct cv *cvp, struct mtx *mp);
void cv_waitq_remove(struct proc *p);

6
sys/sys/systm.h
View File

@ -259,8 +259,10 @@ int msleep __P((void *chan, struct mtx *mtx, int pri, const char *wmesg,
int asleep __P((void *chan, int pri, const char *wmesg, int timo));
#define await(pri, timo) mawait(NULL, pri, timo)
int mawait __P((struct mtx *mtx, int pri, int timo));
void wakeup __P((void *chan));
void wakeup_one __P((void *chan));
void mwakeup __P((void *chan, struct mtx *mtx));
#define wakeup(chan) mwakeup(chan, NULL)
void mwakeup_one __P((void *chan, struct mtx *mtx));
#define wakeup_one(chan) mwakeup_one(chan, NULL)
/*
* Common `dev_t' stuff are declared here to avoid #include poisoning