From fb6f8a96f24f6b30e99cc77d78bc0194ffec7a41 Mon Sep 17 00:00:00 2001 From: Dmitry Vyukov Date: Tue, 8 Dec 2015 15:11:27 +0100 Subject: runtime: remove unnecessary wakeups of worker threads Currently we wake up new worker threads whenever we pass through the scheduler with nmspinning==0. This leads to lots of unnecessary thread wake ups. Instead let only spinning threads wake up new spinning threads. For the following program: package main import "runtime" func main() { for i := 0; i < 1e7; i++ { runtime.Gosched() } } Before: $ time ./test real 0m4.278s user 0m7.634s sys 0m1.423s $ strace -c ./test % time seconds usecs/call calls errors syscall 99.93 9.314936 3 2685009 17536 futex After: $ time ./test real 0m1.200s user 0m1.181s sys 0m0.024s $ strace -c ./test % time seconds usecs/call calls errors syscall 3.11 0.000049 25 2 futex Fixes #13527 Change-Id: Ia1f5bf8a896dcc25d8b04beb1f4317aa9ff16f74 Reviewed-on: https://go-review.googlesource.com/17540 Reviewed-by: Austin Clements Run-TryBot: Dmitry Vyukov TryBot-Result: Gobot Gobot --- src/runtime/runtime2.go | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/runtime/runtime2.go') diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go index cfe4589448..86ed846064 100644 --- a/src/runtime/runtime2.go +++ b/src/runtime/runtime2.go @@ -419,7 +419,7 @@ type schedt struct { pidle puintptr // idle p's npidle uint32 - nmspinning uint32 // limited to [0, 2^31-1] + nmspinning uint32 // See "Worker thread parking/unparking" comment in proc.go. // Global runnable queue. runqhead guintptr -- cgit v1.3-5-g9baa