From bd519d0c8734c3e30cb1a8b8217dd9934cd61e25 Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Thu, 25 Jun 2020 14:50:10 -0700 Subject: [PATCH] runtime: don't call setitimer for each thread Previously, on Unix systems, when the profiler was enabled or disabled, we called setitimer once per thread. With this change we instead call it once per process. Change-Id: I90f0189b562e11232816390dc7d55ed154bd836d Reviewed-on: https://go-review.googlesource.com/c/go/+/240003 Run-TryBot: Ian Lance Taylor TryBot-Result: Gobot Gobot Reviewed-by: Keith Randall --- src/runtime/signal_unix.go | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go index 6a11c91fb9..064a0ea100 100644 --- a/src/runtime/signal_unix.go +++ b/src/runtime/signal_unix.go @@ -272,6 +272,12 @@ func setProcessCPUProfiler(hz int32) { atomic.Storeuintptr(&fwdSig[_SIGPROF], getsig(_SIGPROF)) setsig(_SIGPROF, funcPC(sighandler)) } + + var it itimerval + it.it_interval.tv_sec = 0 + it.it_interval.set_usec(1000000 / hz) + it.it_value = it.it_interval + setitimer(_ITIMER_PROF, &it, nil) } else { // If the Go signal handler should be disabled by default, // switch back to the signal handler that was installed @@ -296,23 +302,16 @@ func setProcessCPUProfiler(hz int32) { setsig(_SIGPROF, h) } } + + setitimer(_ITIMER_PROF, &itimerval{}, nil) } } // setThreadCPUProfiler makes any thread-specific changes required to // implement profiling at a rate of hz. +// No changes required on Unix systems. func setThreadCPUProfiler(hz int32) { - var it itimerval - if hz == 0 { - setitimer(_ITIMER_PROF, &it, nil) - } else { - it.it_interval.tv_sec = 0 - it.it_interval.set_usec(1000000 / hz) - it.it_value = it.it_interval - setitimer(_ITIMER_PROF, &it, nil) - } - _g_ := getg() - _g_.m.profilehz = hz + getg().m.profilehz = hz } func sigpipe() {