1837602 - Disable Spectre JIT mitigations in Fission content processes

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P1)

Description

[Jan de Mooij [:jandem]]

Filing this bug to track flipping the javascript.options.spectre.disable_for_isolated_content pref when we're ready.

Comment 1

[Olli Pettay [:smaug][[e-mail]]]

I think we should start first Nightly only, that is where ORB has been enabled for some time now.

Comment 2

[Jan de Mooij [:jandem]]

(In reply to Olli Pettay [:smaug][[e-mail]] from comment #1)

I think we should start first Nightly only, that is where ORB has been enabled for some time now.

Agreed. Enabling it Nightly-only soon is what we were thinking and then later we can let it ride the trains.

Comment 3

[Jan de Mooij [:jandem]]

Attachment: Bug 1837602 - Disable JS Spectre mitigations for Fission content processes in Nightly. r?iain!

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/47d6f0032249
Disable JS Spectre mitigations for Fission content processes in Nightly. r=iain

Comment 6

[Cristina Horotan [:chorotan]]

https://hg.mozilla.org/mozilla-central/rev/47d6f0032249

Comment 7

[Tetsuharu OHZEKI [:tetsuharu] (UTC+9)]

I seem Fission have not enabled for Android yet (Bug 1610822?)
https://searchfox.org/mozilla-central/rev/6755226f52a02eac8b18f25a6f522e9c0814b628/modules/libpref/init/StaticPrefList.yaml#5142

We need still enable this mitigation for Android even if Nightly build?

Comment 8

[Jan de Mooij [:jandem]]

(In reply to Tetsuharu OHZEKI [:tetsuharu] (UTC+9) from comment #7)

We need still enable this mitigation for Android even if Nightly build?

Mitigations are still enabled on Android because we only disable them for Fission isolated processes. See here.

Comment 9

[Tetsuharu OHZEKI [:tetsuharu] (UTC+9)]

(In reply to Jan de Mooij [:jandem] from comment #8)

(In reply to Tetsuharu OHZEKI [:tetsuharu] (UTC+9) from comment #7)

We need still enable this mitigation for Android even if Nightly build?

Mitigations are still enabled on Android because we only disable them for Fission isolated processes. See here.

Thank you!

Comment 10

[Andrej (:aglavic)]

== Change summary for alert #38896 (as of Tue, 27 Jun 2023 23:24:04 GMT) ==

Improvements:

Ratio	Test	Platform	Options	Absolute values (old vs new)
37%	perf_reftest_singletons getElementById-1.html	windows10-64-shippable-qr	e10s fission stylo webrender	47.42 -> 29.79
11%	kraken	linux1804-64-shippable-qr	e10s fission stylo webrender	1,370.08 -> 1,218.18
9%	kraken	windows10-64-shippable-qr	e10s fission stylo webrender	1,140.08 -> 1,040.41
8%	dromaeo_css	windows10-64-shippable-qr	e10s fission stylo webrender	19,346.58 -> 20,888.91
3%	pdfpaint	linux1804-64-shippable-qr	e10s fission stylo webrender-sw	753.63 -> 730.87

For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=38896(In reply to Pulsebot from comment #5)

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/47d6f0032249
Disable JS Spectre mitigations for Fission content processes in Nightly.
r=iain