Author: mjg
Date: Tue Sep 6 17:16:59 2016
New Revision: 305482
URL: https://svnweb.freebsd.org/changeset/base/305482
Log:
cv: do a lockless check for no waiters in cv_signal and cv_broadcastpri
In case of some consumers like zfs there are no waiters vast majority of
the time
Reviewed by: jhb
MFC after: 1 week
Modified:
head/sys/kern/kern_condvar.c
Modified: head/sys/kern/kern_condvar.c
==============================================================================
--- head/sys/kern/kern_condvar.c Tue Sep 6 17:08:31 2016
(r305481)
+++ head/sys/kern/kern_condvar.c Tue Sep 6 17:16:59 2016
(r305482)
@@ -397,6 +397,8 @@ cv_signal(struct cv *cvp)
{
int wakeup_swapper;
+ if (cvp->cv_waiters == 0)
+ return;
wakeup_swapper = 0;
sleepq_lock(cvp);
if (cvp->cv_waiters > 0) {
@@ -424,6 +426,8 @@ cv_broadcastpri(struct cv *cvp, int pri)
{
int wakeup_swapper;
+ if (cvp->cv_waiters == 0)
+ return;
/*
* XXX sleepq_broadcast pri argument changed from -1 meaning
* no pri to 0 meaning no pri.
_______________________________________________
svn-src-all@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
