1246388 - 2.5-4% win7/win8 sessionrestore/ts_paint regressions on inbound (v.47) on Feb 2 from push 7756089b8570

Status: RESOLVED FIXED

(Core :: Graphics: Layers, defect)

Description

[Joel Maher ( :jmaher ) (UTC -8)]

We see a few regressions on inbound from bug 1238496.

Here are the win8 regressions:
https://treeherder.mozilla.org/perf.html#/compare?originalProject=mozilla-inbound&originalRevision=18868fec4be0&newProject=mozilla-inbound&newRevision=7756089b8570&framework=1

and for win7, we had a failed build, so I had to push to try and compare there:
https://treeherder.mozilla.org/perf.html#/compare?originalProject=mozilla-inbound&originalRevision=18868fec4be0&newProject=try&newRevision=7c478556e289&framework=1

here is information about the tests:
https://wiki.mozilla.org/Buildbot/Talos/Tests#sessionrestore.2Fsessionrestore_no_auto_restore
https://wiki.mozilla.org/Buildbot/Talos/Tests#ts_paint

and here is how you can push to try:
try: -b o -p win32,win64 -u none -t other,other-e10s

Comment 1

[Joel Maher ( :jmaher ) (UTC -8)]

:dvander, can you take a look at this and let us know:
* is this expected
* is there anything we can do to reduce this
* if we need to accept this as a regression, we need to document why it is causing the regression

Comment 2

[David Anderson [:dvander] - inactive, e-mail if emergency]

ACK, looking into this. I would not expect a regression seeing as we didn't see one for D3D9 or OGL, and as far as I know Talos tests' CSS does not use "mix-blend-mode" anywhere.

However this patch did change shader bytecode and added more initialization steps for D3D11 so maybe that was enough to make numbers twitch.

Comment 3

[David Anderson [:dvander] - inactive, e-mail if emergency]

I think the regression is just compiling the extra shader on startup. It's a huge shader. 

Baseline: https://treeherder.mozilla.org/#/jobs?repo=try&revision=925919531b0d
Test: https://treeherder.mozilla.org/#/jobs?repo=try&revision=b125074bd622

I'll do one more follow-up test to make it lazily initialized. If that doesn't work, then the shader itself is slow and for some reason the mix-blend path is being hit. If that's the case, we should just take the regression since it's still a big net win for scrolling smoothness.

Comment 4

[David Anderson [:dvander] - inactive, e-mail if emergency]

Attachment: bug1246388.patch

Yup, apparently the blend shader is big enough to affect compositor startup. Might as well make it lazy. With this applied, Talos numbers on try look back to normal.

Comment 5

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/63ff40690fcd

Comment 6

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/63ff40690fcd

Comment 7

[Joel Maher ( :jmaher ) (UTC -8)]

verified the improvements on perfherder graphs!  Thanks for getting this fixed:)

Comment 8

[David Anderson [:dvander] - inactive, e-mail if emergency]

Comment on attachment 8719114 [details] [diff] [review]
bug1246388.patch

Approval Request Comment
[Feature/regressing bug #]: bug 1238496
[User impact if declined]: Startup time regression
[Describe test coverage new/current, TreeHerder]: Nightly, Talos
[Risks and why]: No risk. This isn't terribly important, but if we uplift bug 1238496 without this we will get small Talos regressions due to slightly increased startup time.
[String/UUID change made/needed]:

Comment 9

[Liz Henry (:lizzard) (relman/hg->git project)]

Comment on attachment 8719114 [details] [diff] [review]
bug1246388.patch

Verified on m-c, fixes a recent perf regression. 
This should land for the beta 1 build.