mirror
/
go
mirror of https://github.com/golang/go.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

runtime: use maxprocs instead of stwprocs for GC CPU pause time metrics 

Currently we use stwprocs as the multiplier for the STW CPU time
computation, but this isn't the same as GOMAXPROCS, which is used for
the total time in the CPU metrics. The two numbers need to be
comparable, so this change switches to using maxprocs to make it so.

Change-Id: I423e3c441d05b1bd656353368cb323289661e302
Reviewed-on: https://go-review.googlesource.com/c/go/+/570256
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Nicolas Hillegeer <aktau@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Michael Anthony Knyszek 2024-03-08 23:02:34 +00:00 committed by Gopher Robot
parent 08a7ab97ba
commit ae0a08dee9
2 changed files with 15 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
src/runtime/mgc.go
View File

@ -748,7 +748,11 @@ func gcStart(trigger gcTrigger) {
work.tMark = now
// Update the CPU stats pause time.
work.cpuStats.accumulateGCPauseTime(now-work.tSweepTerm, work.stwprocs)
//
// Use maxprocs instead of stwprocs here because the total time
// computed in the CPU stats is based on maxprocs, and we want them
// to be comparable.
work.cpuStats.accumulateGCPauseTime(now-work.tSweepTerm, work.maxprocs)
// Release the CPU limiter.
gcCPULimiter.finishGCTransition(now)
@ -1018,8 +1022,13 @@ func gcMarkTermination(stw worldStop) {
// Accumulate CPU stats.
//
// Pass gcMarkPhase=true so we can get all the latest GC CPU stats in there too.
work.cpuStats.accumulateGCPauseTime(work.tEnd-work.tMarkTerm, work.stwprocs)
// Use maxprocs instead of stwprocs for GC pause time because the total time
// computed in the CPU stats is based on maxprocs, and we want them to be
// comparable.
//
// Pass gcMarkPhase=true to accumulate so we can get all the latest GC CPU stats
// in there too.
work.cpuStats.accumulateGCPauseTime(work.tEnd-work.tMarkTerm, work.maxprocs)
work.cpuStats.accumulate(now, true)
// Compute overall GC CPU utilization.

6
src/runtime/mstats.go
View File

@ -922,11 +922,11 @@ type cpuStats struct {
}
// accumulateGCPauseTime add dt*stwProcs to the GC CPU pause time stats. dt should be
// the actual time spent paused, for orthogonality. stwProcs should be GOMAXPROCS,
// the actual time spent paused, for orthogonality. maxProcs should be GOMAXPROCS,
// not work.stwprocs, since this number must be comparable to a total time computed
// from GOMAXPROCS.
func (s *cpuStats) accumulateGCPauseTime(dt int64, stwProcs int32) {
cpu := dt * int64(stwProcs)
func (s *cpuStats) accumulateGCPauseTime(dt int64, maxProcs int32) {
cpu := dt * int64(maxProcs)
s.gcPauseTime += cpu
s.gcTotalTime += cpu
}