Closed Bug 1667804 Opened 2 years ago Closed 2 years ago

Enable stencil-mvp by default


(Core :: JavaScript Engine, task, P1)




86 Branch
Tracking Status
firefox86 --- fixed


(Reporter: tcampbell, Assigned: tcampbell)



(Keywords: perf-alert)


(1 file)

Placeholder bug for the pref-flip of javascript.options.use_off_thread_parse_global when we are ready.

Flips the javascript.options.use_off_thread_parse_global pref to false.
This allows off-main-thread JS parsing to run even while the atoms-zone is
being GC'd. This fixes intermittent stalls where an incremental GC on
main-thread can cause large off-thread parse requests to go into wait queues
until the GC is finished.

This change is focused on addressing these intermittent stalls that are based
on particulars of GC timing. Different machines may or may not see stalls on
the same webpages.

Note that the system ScriptPreloader that runs during process startup still
uses an off-thread parse global. This bug is focused on improving the content
ScriptLoader during normal page-load.

Attachment #9178454 - Attachment description: Bug 1667804 - Enable stencil-mvp → Bug 1667804 - Enable stencil-mvp pref. r?arai!
Depends on: 1686691
Closed: 2 years ago
Resolution: --- → FIXED
Target Milestone: --- → 86 Branch
Regressions: 1687228

== Change summary for alert #28499 (as of Wed, 20 Jan 2021 09:14:44 GMT) ==


Ratio Suite Test Platform Options Absolute values (old vs new)
3% google-sheets loadtime linux64-shippable-qr nocondprof warm webrender 936.12 -> 965.25


Ratio Suite Test Platform Options Absolute values (old vs new)
3% bbc LastVisualChange android-hw-g5-7-0-arm7-api-16-shippable nocondprof warm webrender 3,097.17 -> 3,008.75
2% twitter loadtime linux64-shippable nocondprof warm 581.96 -> 567.79
2% twitter loadtime linux64-shippable-qr nocondprof warm webrender 610.02 -> 595.38
2% twitter loadtime linux64-shippable nocondprof warm 582.19 -> 569.00
2% twitter SpeedIndex linux64-shippable nocondprof warm 805.38 -> 787.92
2% instagram loadtime android-hw-g5-7-0-arm7-api-16-shippable nocondprof warm webrender 2,249.10 -> 2,200.75

For up to date results, see:

Keywords: perf-alert

Bug 1687602 will optimize this further and the google-sheets regression should turn into a improvement as well. I'll double check if there is anything to learn from that specific case though.

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