1694471 - WebRender Android: slow frames on mozilla.org

Status: UNCONFIRMED

(Core :: Graphics: WebRender, defect)

Description

[Mark]

Attachment: Jank.jpg

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:87.0) Gecko/20100101 Firefox/87.0

Steps to reproduce:

Copied from https://bugzilla.mozilla.org/show_bug.cgi?id=1658205#c39

Flinging mozilla.org shows major WebRender CPU spikes on my Galaxy A40 and Galaxy S7 (both Exynos) and a lot of jank. I think the jank correlates with the CPU spikes. Screenshot attached. Mostly when the images fade in eg the Capitol building first image. 25-30 ms spike is not uncommon. See this on other sites too but mozilla.org is particularly bad.

Comment 1

[Jamie Nicol [:jnicol]]

Could you please capture an up to date profile Mark? Using the Firefox Graphics preset to make sure the webrender threads are captured and that screenshots are disabled. Thanks!

Comment 2

[Mark]

https://share.firefox.dev/3sl0Bhk

This is mozilla.org on today's Fenix Nightly on my Galaxy A40. I scrolled the page to the top, reloaded it and gently flinged (flung?) so the first image (domed building) faded in. I repeated three times. I saw BIG jank each time on the image fade. Of course, some of the jank might be bug 1658205.

Comment 3

[Glenn Watson [:gw]]

Is this still an issue?

Comment 4

[Mark]

Hmmm difficult to say
(1) mozilla.org doesn't seem to have animationed fade-ins any more
(2) my Galaxy M32 has a somewhat faster CPU/GPU combo than my old A40

But I still see big jank and big slow frames on other sites which have animation fade ins, eg

reuters.com:-
https://share.firefox.dev/3KfgIY0

bbc.co.uk/news:-
https://share.firefox.dev/3PLOQfc

Basically image fade-ins can still cause quite a lot of scroll jank but I'm not sure it's the same issue as I originally filed against mozilla.org. Reuters is awful but it's not great on Chromium either.

On the built in profiler (on my Android phone screen) the animation fade-in jank still correlates with Frame CPU Total spikes of eg 30-40 ms and many red lines in that chart.

Comment 5

[Mark]

https://blog.mozilla.org/en is pretty awful, very janky

https://share.firefox.dev/3CBBSgW

lots of red spikes in Frame CPU Total, up to 100 ms high