svn commit: r285511 - head/sys/kern

[Mateusz Guzik]

Author: mjg
Date: Mon Jul 13 22:52:11 2015
New Revision: 285511
URL: https://svnweb.freebsd.org/changeset/base/285511

Log:
  racct: perform a lockless check for p_throttled
  
  This reduces proc lock contention.
  
  Reviewed by:	trasz

Modified:
  head/sys/kern/subr_trap.c

Modified: head/sys/kern/subr_trap.c
==============================================================================
--- head/sys/kern/subr_trap.c	Mon Jul 13 21:01:24 2015	(r285510)
+++ head/sys/kern/subr_trap.c	Mon Jul 13 22:52:11 2015	(r285511)
@@ -172,7 +172,7 @@ userret(struct thread *td, struct trapfr
 	    (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
 #endif
 #ifdef RACCT
-	if (racct_enable) {
+	if (racct_enable && p->p_throttled == 1) {
 		PROC_LOCK(p);
 		while (p->p_throttled == 1)
 			msleep(p->p_racct, &p->p_mtx, 0, "racct", 0);