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Issue 886920 link

Starred by 1 user
Status: Untriaged
Owner: ----
Cc:
flackr@chromium.org
vmi...@chromium.org
dproy@chromium.org
tdres...@chromium.org
bokan@chromium.org
Components:
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: 3
Type: Bug



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Scrolling in chrome:tracing is janky

Project Member Reported by sadrul@chromium.org, Sep 19 
Scrolling in chrome:tracing is often janky. Attached is a trace for that. Note the ~300ms long PageAnimator::serviceScriptedAnimations trace-events at ~2670ms and ~3021ms, which align with the janks.

Not sure who the right owner is. cc'ing some folks who might know the right owner.
trace_scrolling-in-chrome-tracing.json.gz
1.6 MB Download

Comment 1 by tdres...@chromium.org, Sep 19 

Just checking - do you think this is jankier than it was before?

Comment 2 by sadrul@chromium.org, Sep 19 

I am honestly not sure, but it does feel jankier than it used to be.

Comment 3 by sadrul@chromium.org, Sep 19 

Does chrome:tracing even have any 'scripted animations' (I assume those mean raf-animations in js)?

Comment 4 by sadrul@chromium.org, Sep 25

Components: Internals>Compositing>Scroll

Comment 5 by kevers@chromium.org, Sep 26

Components: -Internals>Compositing>Scroll Blink>Scroll
Look at the speed trace, it does not appear to be a problem with compositing.  The critical time step appears to be on the main thread.

Comment 6 by bokan@chromium.org, Oct 26

Cc: bokan@chromium.org
Components: -Blink>Scroll
This is likely a page issue, I'm assuming there's some JS running but the trace has v8 categories excluded. Sadrul, maybe capturing with all categories could help narrow down what's going on in serviceScriptedAnimations? Capturing a DevTools trace should also surface more info about what JS is running...
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