1836948 - Prototype making the main thread part of the rayon thread pool.

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, task)

Comment 1

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1836948 - Update rayon-core. r=glandium

Depends on D179492

Comment 2

[Emilio Cobos Álvarez (:emilio)]

Attachment: WIP: Bug 1836948 - DO NOT LAND: Patch rayon-core with use_current prototype from rayon#1052.

Depends on D180074

Comment 3

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1836948 - Use the main thread as part of the style thread pool. r=smaug,#style

Depends on D180075

Comment 4

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1836948 - Update rayon-core. r=glandium

Depends on D179492

Comment 5

[Emilio Cobos Álvarez (:emilio)]

Attachment: WIP: Bug 1836948 - DO NOT LAND: Patch rayon-core with use_current prototype from rayon#1052.

Depends on D180077

Comment 6

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1836948 - Use the main thread as part of the style thread pool. r=smaug,#style

Depends on D180078

Comment 7

[Emilio Cobos Álvarez (:emilio)]

Initial comparison: https://treeherder.mozilla.org/perfherder/compare?originalProject=try&originalRevision=32b4e24392da47877d9342f90ddd6536bd36015d&newProject=try&newRevision=53a843a85c0fd9e3c78f707c3d143d25c5521106

Comment 8

[Emilio Cobos Álvarez (:emilio)]

Attachment: WIP: Bug 1836948 - Now the main thread can steal work so make it behave like another worker thread.

Depends on D180079

Comment 9

[Emilio Cobos Álvarez (:emilio)]

With comment 8: https://treeherder.mozilla.org/perfherder/compare?originalProject=try&originalRevision=32b4e24392da47877d9342f90ddd6536bd36015d&newProject=try&newRevision=9283d26c3b46b0338ed32be017d8ea1a0603f204

Comment 10

[Emilio Cobos Álvarez (:emilio)]

Pageload tests: https://treeherder.mozilla.org/perfherder/compare?originalProject=try&originalRevision=778a2e690e6915ad1debf6a1face1b2326887bfc&newProject=try&newRevision=adf01e35456ea09a3bdc4d73a3a8502e3bfee2f9&page=1

Comment 11

[Emilio Cobos Álvarez (:emilio)]

Some tweak: https://treeherder.mozilla.org/perfherder/compare?originalProject=try&originalRevision=32b4e24392da47877d9342f90ddd6536bd36015d&newProject=try&newRevision=15e96e0b09c50cd7d3b02a7e26569c60729201cd / https://treeherder.mozilla.org/perfherder/compare?originalProject=try&originalRevision=778a2e690e6915ad1debf6a1face1b2326887bfc&newProject=try&newRevision=66f0a53bcfb5ec1e847d830b431cebc226f04367

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a157866c741c
Update rayon-core. r=glandium,supply-chain-reviewers

Comment 13

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/a157866c741c

Comment 14

[Emilio Cobos Álvarez (:emilio)]

Jeff, if it's not too much work, could you get a visualization like the one you posted in https://github.com/rayon-rs/rayon/issues/1052 but with the patches? (I haven't used the android GPU profiler thing). If you can't let me know and I can give it a shot.

Comment 15

[Jeff Muizelaar [:jrmuizel]]

I'll get the visualization

Comment 16

[Jeff Muizelaar [:jrmuizel]]

Attachment: scheduling-try.png

This is with the patches applied.

The little cores are completely swamped with other work. During this time the style threads spend a lot of time waiting to be scheduled and it seems the main thread runs out of work to do. It then goes idle and gets clocked down while waiting for the style thread 4 to get scheduled.

Comment 17

[Jeff Muizelaar [:jrmuizel]]

Attachment: scheduling-more-work-fewer-threads.png

Here's a version with layout.css.stylo-local-work-queue.in-main-thread=128 and layout.css.stylo-threads=4. With it we still do some sleeping on the main thread but we do also manage to do quite a bit of style work in parallel. We don't seem to sleep long enough for the big core to clock down.

Comment 18

[Emilio Cobos Álvarez (:emilio)]

https://treeherder.mozilla.org/jobs?repo=try&revision=ac0ee57e8b0af2b3602776347fbe3b3659afb30f / https://treeherder.mozilla.org/perfherder/compare?originalProject=try&originalRevision=4546bf49916667685fc48bb3cbadfff9c1490de8&newProject=try&newRevision=ac0ee57e8b0af2b3602776347fbe3b3659afb30f with a fix for a bug that prevented the main thread from being prioritized once it ran out of work.

Comment 19

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1836948 - Patch rayon-core with proposed use_current_thread API. r=smaug,jnicol

This applies https://github.com/rayon-rs/rayon/pull/1063 to our
rayon-core. I'm hopeful it can be merged upstream soon, but meanwhile
this seems worth having on its ow.

Comment 20

[Jamie Nicol [:jnicol]]

Expect this to not make much impact on try: https://treeherder.mozilla.org/perfherder/comparesubtest?originalProject=try&newProject=try&newRevision=0b618823de9df0809f79cb5494f35eb32f471359&originalSignature=4590278&newSignature=4590278&framework=13&application=geckoview&originalRevision=deb4381b061d0263072a19644bb45fc1a765352b&page=1

However, if we disable bug 1812589 it makes a much clearer difference: https://treeherder.mozilla.org/perfherder/comparesubtest?originalProject=try&newProject=try&newRevision=da146544e88323dad8487233830af61ad8c6d324&originalSignature=4590278&newSignature=4590278&framework=13&application=geckoview&originalRevision=ecb27497d42d2d28b95cc7f4bc8ae94bab10d59b&page=1

(The overall score is still low-confidence, but there are many high confidence subtest improvements).

Paired with the affinity changes I'm working on we can get an even better improvement, and I'm also experimenting with the number of threads. But we should land this first in any case.

Comment 21

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b98bce55d272
Patch rayon-core with proposed use_current_thread API. r=smaug,jnicol,supply-chain-reviewers
https://hg.mozilla.org/integration/autoland/rev/d7f697ba002a
Use the main thread as part of the style thread pool. r=smaug

Comment 22

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/b98bce55d272
https://hg.mozilla.org/mozilla-central/rev/d7f697ba002a