1697479 - Consider not poisoning the nursery in nightly opt builds

Status: RESOLVED FIXED

(Core :: JavaScript: GC, task, P3)

Description

[Jon Coppeard (:jonco)]

This isn't catching any bugs at the moment but does it make performance telemetry harder to interpret. It also frequently catches out people trying to benchmark the browser.

We'd still want this enabled for any builds used for fuzzing.

Comment 1

[Jon Coppeard (:jonco)]

Attachment: Bug 1697479 - Turn extra GC poisoning off by default in nightly builds r?sfink

This flips the default so extra GC poisoning off in nightly builds unless enabled by an environment variable. This should give us more useful telemetry on nightly performance and make it easier for people trying to benchmark our browser.

The variable is renamed from JSGC_DISABLE_POISONING to JSGC_EXTRA_POISONING.

What do you think?

Comment 2

[Jon Coppeard (:jonco)]

FYI we're planning on making this change. Fuzzers will want to set JSGC_EXTRA_POISONING in opt builds going forwards to get the same poisoning behaviour.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7cb14dd00756
Turn extra GC poisoning off by default in nightly builds r=sfink,perftest-reviewers,sparky

Comment 4

[Alexandru Michis [:malexandru]]

https://hg.mozilla.org/mozilla-central/rev/7cb14dd00756

Comment 5

[Andra Esanu (needinfo me)]

== Change summary for alert #29333 (as of Fri, 19 Mar 2021 11:30:39 GMT) ==

Improvements:

Ratio	Suite	Test	Platform	Options	Absolute values (old vs new)
6%	Base Content Resident Unique Memory		windows10-64-shippable-qr		10,118,912.00 -> 9,472,853.33
6%	Base Content Resident Unique Memory		windows10-64-shippable-qr		10,146,133.33 -> 9,500,330.67
6%	Base Content Resident Unique Memory		windows10-64-shippable		10,172,074.67 -> 9,556,138.67
2%	Resident Memory		windows10-64-shippable-qr	tp6	691,607,874.82 -> 675,078,368.26

For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=29333