1712123 - Don't tick during the process-switch period

Status: RESOLVED FIXED

(Core :: Layout, enhancement, P3)

Description

[Sean Feng [:sefeng211]]

In the profiles that we have collected, ie https://share.firefox.dev/3bW4dkj and https://share.firefox.dev/3bABHoa, we always see the refreshdriver tick during the process switching period. It usually takes about 1-2ms.

We should avoid doing this tick because we don't really need to paint anything. According to some words from Olli, we might want to modify https://searchfox.org/mozilla-central/rev/2f1a015b004b79f1145c81cdf86b15481a5630e2/layout/base/nsRefreshDriver.cpp#1398 to check for page loads.

Comment 1

[Olli Pettay [:smaug][[e-mail]]]

I think this is a regression from the recent changes which have improved responsiveness.
Should we limit catch-up to happen only after page load?

Comment 2

[Chris Peterson [:cpeterson]]

Tracking for Fission MVP because this would be a nice to fix performance optimization.

Comment 3

[Daniel Holbert [:dholbert]]

I'll put this on my plate for the moment to take it out of the unassigned queue, though we may find another owner for this.

(Also, if this slips off of the MVP list, I suspect users wouldn't notice too much; it doesn't sound like this is a major perf pain point.)

Comment 4

[Chris Peterson [:cpeterson]]

This bug is a soft blocker for Fission MVP. We'd like to fix it before our Release channel rollout, but we won't delay the rollout waiting for it.

Comment 5

[Chris Peterson [:cpeterson]]

This bug would still be nice to fix for Fission MVP (Firefox 94) because it might help with the recent warm load regression bug 1722641 from bfcache-in-parent.

Comment 6

[Daniel Holbert [:dholbert]]

Attachment: Bug 1712123: Don't do refresh-driver "catch-up" ticks until after pageload. r?smaug

The "catch-up" ticks are a strategy to make our repaint cycle more repsonsive
to user interaction, e.g. getting typed characters onto the screen sooner.
During pageload, this strategy isn't as crucial and may in fact harm the
overall pageload performance. So, this patch makes us hold off on these ticks
until after the page has finished loading.

Comment 7

[Daniel Holbert [:dholbert]]

Try run: https://treeherder.mozilla.org/jobs?repo=try&revision=f28e7dc1621bbe7b0b168f60f578784753986d33

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e5a8c52f0f18
Don't do refresh-driver "catch-up" ticks until after pageload. r=smaug

Comment 9

[Marian-Vasile Laza]

https://hg.mozilla.org/mozilla-central/rev/e5a8c52f0f18

Comment 10

[Chris Peterson [:cpeterson]]

Setting status-firefox93=wontfix because we don't need to uplift this tick fix to Beta 93.