Author: markj
Date: Wed May 18 03:50:21 2016
New Revision: 300109
URL: https://svnweb.freebsd.org/changeset/base/300109
Log:
Micro-optimize sleepq_broadcast().
- Avoid a conditional branch on the return value of sleepq_resume_thread()
by ORing its return value into the boolean wakeup_swapper. This is
consistent with other sleepqueue functions which just pass this return
value to their caller.
- sleepq_resume_thread() unconditionally removes the thread from its queue,
so there's no need to maintain a pointer to the next element in the queue.
MFC after: 2 weeks
Modified:
head/sys/kern/subr_sleepqueue.c
Modified: head/sys/kern/subr_sleepqueue.c
==============================================================================
--- head/sys/kern/subr_sleepqueue.c Wed May 18 03:50:18 2016
(r300108)
+++ head/sys/kern/subr_sleepqueue.c Wed May 18 03:50:21 2016
(r300109)
@@ -865,7 +865,7 @@ int
sleepq_broadcast(void *wchan, int flags, int pri, int queue)
{
struct sleepqueue *sq;
- struct thread *td, *tdn;
+ struct thread *td;
int wakeup_swapper;
CTR2(KTR_PROC, "sleepq_broadcast(%p, %d)", wchan, flags);
@@ -879,10 +879,9 @@ sleepq_broadcast(void *wchan, int flags,
/* Resume all blocked threads on the sleep queue. */
wakeup_swapper = 0;
- TAILQ_FOREACH_SAFE(td, &sq->sq_blocked[queue], td_slpq, tdn) {
+ while ((td = TAILQ_FIRST(&sq->sq_blocked[queue])) != NULL) {
thread_lock(td);
- if (sleepq_resume_thread(sq, td, pri))
- wakeup_swapper = 1;
+ wakeup_swapper |= sleepq_resume_thread(sq, td, pri);
thread_unlock(td);
}
return (wakeup_swapper);
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