| commit | e995aa95cb5f379c1df5d5511ee09970261d877f | [log] [tgz] |
|---|---|---|
| author | Michael Anthony Knyszek <mknyszek@google.com> | Mon Mar 25 17:50:13 2024 +0000 |
| committer | Gopher Robot <gobot@golang.org> | Mon Apr 08 21:43:16 2024 +0000 |
| tree | 5b348fd16dd9bac0453d2530027981b2b958e54c | |
| parent | d4395ebc0c90a11a5f31fab0808baf3cb25d6ba8 [diff] |
runtime: account for _Pgcstop in GC CPU pause time in a fine-grained way The previous CL, CL 570257, made it so that STW time no longer overlapped with other CPU time tracking. However, what we lost was insight into the CPU time spent _stopping_ the world, which can be just as important. There's pretty much no easy way to measure this indirectly, so this CL implements a direct measurement: whenever a P enters _Pgcstop, it writes down what time it did so. stopTheWorld then accumulates all the time deltas between when it finished stopping the world and each P's stop time into a total additional pause time. The GC pause cases then accumulate this number into the metrics. This should cause minimal additional overhead in stopping the world. GC STWs already take on the order of 10s to 100s of microseconds. Even for 100 Ps, the extra `nanotime` call per P is only 1500ns of additional CPU time. This is likely to be much less in actual pause latency, since it all happens concurrently. Change-Id: Icf190ffea469cd35ebaf0b2587bf6358648c8554 Reviewed-on: https://go-review.googlesource.com/c/go/+/574215 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Nicolas Hillegeer <aktau@google.com> Auto-Submit: Michael Knyszek <mknyszek@google.com>
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