Add support for perf's jitdump format
Categories
(Core :: JavaScript Engine, enhancement, P3)
Tracking
()
Tracking | Status | |
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firefox103 | --- | fixed |
People
(Reporter: jrmuizel, Assigned: denispal)
References
(Blocks 1 open bug)
Details
Attachments
(2 files)
V8 supports this (--perf-basic-prof
, --perf-prof-unwinding-info
etc.) and it would be useful for being able to profile natively with perf. It could also be useful for being able to compare profiles of JS in V8 vs Spidermonkey.
Reporter | ||
Comment 1•3 years ago
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The format is documented here: https://github.com/torvalds/linux/blob/master/tools/perf/Documentation/jitdump-specification.txt
Reporter | ||
Updated•3 years ago
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Comment 2•3 years ago
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For what is worth, we already have some perf
instrumentation here:
https://searchfox.org/mozilla-central/rev/d4d7611ee4dd0003b492b865bc5988a4e6afc985/js/src/builtin/Profilers.cpp#464
Assignee | ||
Comment 3•3 years ago
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I would definitely like to support this so we can get better visibility into which functions are behaving poorly versus chrome. Right now we can find the problematic function pretty easily in the gecko profiler, but it's hard to understand why it's behaving poorly. So, I don't mind taking this if nobody else is planning on working on it.
Assignee | ||
Updated•3 years ago
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Comment 4•2 years ago
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(In reply to Nicolas B. Pierron [:nbp] from comment #2)
For what is worth, we already have some
perf
instrumentation here:
And more here: (requires building with --enable-perf
and running with IONPERF=func/block
)
https://searchfox.org/mozilla-central/rev/44527269dd96db7a3da81aafff33c84a031864c7/js/src/jit/PerfSpewer.cpp
This supports the old perf.map format, not the newer jitdump format. (some more notes here)
Assignee | ||
Comment 5•2 years ago
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The existing support for perf symbol maps will be removed in favour of jitdump.
Assignee | ||
Comment 6•2 years ago
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Assignee | ||
Comment 7•2 years ago
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Depends on D148035
Comment 9•2 years ago
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bugherder |
https://hg.mozilla.org/mozilla-central/rev/abefa20046ff
https://hg.mozilla.org/mozilla-central/rev/ba893c6048b5
Comment 10•2 years ago
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== Change summary for alert #34478 (as of Tue, 14 Jun 2022 19:14:42 GMT) ==
Improvements:
Ratio | Test | Platform | Options | Absolute values (old vs new) |
---|---|---|---|---|
2% | buzzfeed PerceptualSpeedIndex | macosx1015-64-shippable-qr | fission warm webrender | 269.75 -> 264.25 |
For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=34478
Description
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