From: Dmitriy Vyukov <dvyukov@google.com>
Date: Fri, 19 Jul 2013 13:45:34 +0000 (+0400)
Subject: runtime: prevent sysmon from polling network excessivly
X-Git-Tag: go1.2rc2~997
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=68572644576be5f1f7121428755e7d8af5b7044c;p=gostls13.git

runtime: prevent sysmon from polling network excessivly
If the network is not polled for 10ms, sysmon starts polling network
on every iteration (every 20us) until another thread blocks in netpoll.
Fixes #5922.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/11569043
---

diff --git a/src/pkg/runtime/proc.c b/src/pkg/runtime/proc.c
index fe32f2c28b..18ddce8018 100644
--- a/src/pkg/runtime/proc.c
+++ b/src/pkg/runtime/proc.c
@@ -2098,6 +2098,7 @@ sysmon(void)
 		lastpoll = runtime·atomicload64(&runtime·sched.lastpoll);
 		now = runtime·nanotime();
 		if(lastpoll != 0 && lastpoll + 10*1000*1000 > now) {
+			runtime·cas64(&runtime·sched.lastpoll, lastpoll, now);
 			gp = runtime·netpoll(false);  // non-blocking
 			injectglist(gp);
 		}