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From: Mark Johnston <markj@FreeBSD.org>
Date: Sun, 4 Sep 2016 00:29:49 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r305368 - head/sys/kern
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Author: markj
Date: Sun Sep  4 00:29:48 2016
New Revision: 305368
URL: https://svnweb.freebsd.org/changeset/base/305368

Log:
  Micro-optimize sleepq_signal().
  
  Lift a comparison out of the loop that finds the highest-priority thread
  on the queue.
  
  MFC after:	1 week

Modified:
  head/sys/kern/subr_sleepqueue.c

Modified: head/sys/kern/subr_sleepqueue.c
==============================================================================
--- head/sys/kern/subr_sleepqueue.c	Sun Sep  4 00:25:49 2016	(r305367)
+++ head/sys/kern/subr_sleepqueue.c	Sun Sep  4 00:29:48 2016	(r305368)
@@ -861,9 +861,9 @@ sleepq_signal(void *wchan, int flags, in
 	 * been sleeping the longest since threads are always added to
 	 * the tail of sleep queues.
 	 */
-	besttd = NULL;
+	besttd = TAILQ_FIRST(&sq->sq_blocked[queue]);
 	TAILQ_FOREACH(td, &sq->sq_blocked[queue], td_slpq) {
-		if (besttd == NULL || td->td_priority < besttd->td_priority)
+		if (td->td_priority < besttd->td_priority)
 			besttd = td;
 	}
 	MPASS(besttd != NULL);