[release-branch.go1.1] runtime: prevent sysmon from polling network excessivly

adg · adg · commit ceeda72babae · 2013-07-23T09:50:35.000+10:00
««« CL 11569043 / 6b3c351c7fe6 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 issue 5922 . R=golang-dev, iant CC=golang-dev https://golang.org/cl/11569043 »»» Update #5928 R=golang-dev, bradfitz CC=golang-dev https://golang.org/cl/11438044
diff --git a/src/pkg/runtime/proc.c b/src/pkg/runtime/proc.c
@@ -2015,6 +2015,7 @@ 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);
 		}

Original file line number	Diff line number	Diff line change
`@@ -2015,6 +2015,7 @@ sysmon(void)`
`2015`	`2015`	`lastpoll = runtime·atomicload64(&runtime·sched.lastpoll);`
`2016`	`2016`	`now = runtime·nanotime();`
`2017`	`2017`	`if(lastpoll != 0 && lastpoll + 1010001000 > now) {`
	`2018`	`+ runtime·cas64(&runtime·sched.lastpoll, lastpoll, now);`
`2018`	`2019`	`gp = runtime·netpoll(false); // non-blocking`
`2019`	`2020`	`injectglist(gp);`
`2020`	`2021`	`}`