928056 - Unbreak GGC on AWFY

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Terrence Cole [:terrence]]

When IonBuilder moved off main thread, we started blocking on completion of background threads in AutoTraceSession. For normal GC's this isn't such a big deal, but when it happens every minor collection, we get a catastrophic slowdown. This was slow enough that it took AWFY completely down last week.

See bug 928050 for the complete fix: this is just a quick hack to make GGC work again.

Comment 1

[Terrence Cole [:terrence]]

Attachment: extract_pause_from_tracing-v0.diff

This unbundles AutoPauseWorkersForGC from AutoTraceSession and renames it to AutoPauseWorkersForTracing. I then manually re-added the pause all the places it was before except for generational GC's. This takes my local time for running octane from 8m30s -> 30s.

Comment 2

[Terrence Cole [:terrence]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/61f6c63bcb3d

Comment 3

[Terrence Cole [:terrence]]

Attachment: fix_ordering_of_state_change-v0.diff

This changed the ordering of swapping the state and pausing in AutoGCSession, which causes us to occasionally fire spurious assertions. This will be fixed by bug 928050, but in the meantime we should stop the intermittent orange by fixing the ordering.

Comment 4

[Terrence Cole [:terrence]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/d6180c846c36

Comment 5

[Terrence Cole [:terrence]]

And backed out because I forgot about runtime and apparently can't keep my patches straight when testing.
https://hg.mozilla.org/integration/mozilla-inbound/rev/3b459fed3fc6

Comment 6

[Ryan VanderMeulen [:RyanVM]]

Let's get the original landing while we're at it.
https://hg.mozilla.org/integration/mozilla-inbound/rev/a46ff1a56160

Comment 7

[Ryan VanderMeulen [:RyanVM]]

BTW, these also showed up on your original push:
https://tbpl.mozilla.org/php/getParsedLog.php?id=29327224&tree=Mozilla-Inbound

Comment 8

[Terrence Cole [:terrence]]

Once more unto the breach:
https://hg.mozilla.org/integration/mozilla-inbound/rev/b1ce50371389

Comment 9

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/b1ce50371389