1398140 - Consider removing the Ion helper thread pausing

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, enhancement)

Description

[Jan de Mooij [:jandem]]

We have this mechanism where we allow 1 helper thread at a time to do Ion compilation. If a higher priority task comes in, we can pause other compilation threads, process the new task on a new thread, then unpause the paused thread(s).

This adds quite a lot of complexity (to code that's already complicated enough!). It also has some issues:

* We would like to Ion-compile scripts in parallel, especially when the CPU has 4+ cores.

* Pausing compilation threads means these threads are not available for other tasks (GC, Wasm, parsing).

* IonBuilderHasHigherPriority includes the size and warm up count of the outer script, but due to inlining it's not clear whether that's very useful.

Removing the pausing mechanism improves shell benchmarks a bit locally. I'll check how this affects Speedometer on AWFY.

Comment 1

[Jan de Mooij [:jandem]]

Attachment: Patch

Mostly just removing code:

 5 files changed, 9 insertions(+), 185 deletions(-)

This improves shell benchmarks locally. I'm not sure about Speedometer (my AWFY-Try run failed for some reason). I think we should just land it and see what happens on AWFY.

Comment 2

[Luke Wagner [:luke]]

Comment on attachment 8906512 [details] [diff] [review]
Patch

Review of attachment 8906512 [details] [diff] [review]:
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Great!

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/ab8c75e0d422
Remove Ion helper thread pausing mechanism. r=luke

Comment 4

[Jan de Mooij [:jandem]]

For posterity: some minor regressions on AWFY but overall this was an improvement. 7-9% on Kraken crypto-ccm, 2.2% on Octane mandreel, small win on Sunspider. Some of the improvements are bigger on 32-bit (> 11% on Kraken crypto-ccm). Not too bad for a code removal patch.

Will be interesting to see if this has any effect on the (slower) QF hardware or on Talos.

Comment 5

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

https://hg.mozilla.org/mozilla-central/rev/ab8c75e0d422