1900778 - JitHits can prevent pretenuring allocations

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, task)

Description

[Jon Coppeard (:jonco)]

Pretenuring allocations requires the script to run in baseline long enough to gather data about the allocation site. This can be subverted by JitHits which can set the Ion compilation threshold to below that required by pretenuring.

Comment 1

[Jon Coppeard (:jonco)]

Attachment: Bug 1900778 - Don't set ion compilation threshold hint too low for scripts with pretenured alloation sites r?jandem

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5ea60c3ca92c
Don't set ion compilation threshold hint too low for scripts with pretenured alloation sites r=jandem

Comment 3

[pstanciu]

https://hg.mozilla.org/mozilla-central/rev/5ea60c3ca92c

Comment 4

[Alex Finder]

(In reply to Pulsebot from comment #2)

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5ea60c3ca92c
Don't set ion compilation threshold hint too low for scripts with pretenured
alloation sites r=jandem

Perfherder has detected a browsertime performance change from push 5ea60c3ca92c3edf3b0a5feeae44c88afc2a93fc.

Improvements:

Ratio	Test	Platform	Options	Absolute values (old vs new)	Performance Profiles
9%	expedia LastVisualChange	macosx1015-64-shippable-qr	fission warm webrender	2,370.47 -> 2,167.47	Before/After

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests.

If you need the profiling jobs you can trigger them yourself from treeherder job view or ask a sheriff to do that for you.

You can run these tests on try with ./mach try perf --alert 666

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