commit | f8e58737ebe83853bef263d8fc238af33eebdb33 | [log] [tgz] |
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author | Jens Johansen <jensj@google.com> | Thu Feb 15 10:30:09 2024 +0000 |
committer | Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> | Thu Feb 15 10:30:09 2024 +0000 |
tree | 2a76bea8f73ccd9c05bc904a46ff19a2939c0649 | |
parent | dc586994daaf5d94272d96be29211178ea6f0c2e [diff] |
[CFE] Add perf event lister tool; more visible warning for benchmarker when scaling is in effect I do some benchmarking with our benchmarker tool which uses "perf stat" under the hood. "perf stat" uses hardware counters, but we have a limited amount of those. The benchmarker tool asks for 3 event types that will use 3 hardware counters. If there aren't 3 available it will do "scaling" and only measure what it's asked some percentage of the time so it can still measure all of the stuff it's asked. This should be fine. My computer has 4 hardware counters. I think. Only today I still experienced scaling. And previously I asked for 4 event types because I had 4 hardware counters, but then suddenly 1 went missing. As it turns out another process was using hardware counters. This CL includes a tool that - at least seeems to - be able to find other processes using perf events (although it might not be events that use hardware counters), thus possibly allowing you to kill that or those process(es). I did, and I now have 4 hardware counters again. I also made scaling more visible if it happens when using the benchmark tool. Before it was hidden between other output, not it's also printed at the end, together with a hint to use the new tool to attempt to fix it. Change-Id: Ia51db04a4f25d1d82c3d32b3901cded7d980e7f5 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/352525 Commit-Queue: Jens Johansen <jensj@google.com> Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>
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