1053078 - ASAP mode breaks refresh driver throttling

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Matt Woodrow (:mattwoodrow)]

The refresh driver throttling code has a safety mechanism where we unblock painting if we get 10 refresh driver ticks while frozen. This exists to stop us getting deadlocked if a response from the compositor gets lost somehow.

ASAP mode (where we trigger refresh driver ticks as fast as possible) breaks this since we accumulate the 10 ticks almost immediately, even when the compositor is responding normally.

We use this mode for most of our talos test, so the results (particularly on OSX) will likely appear to regress when we fix this since we'll correctly be keeping content in sync with the compositor instead of overproducing.

Comment 1

[Matt Woodrow (:mattwoodrow)]

Adding avih and jmaher to the cc list since this is going to show up as a talos regression.

Comment 2

[Matt Woodrow (:mattwoodrow)]

Attachment: refresh-driver-talos

Comment 3

[Matt Woodrow (:mattwoodrow)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/76d4e6230498

Comment 4

[Avi Halachmi (:avih)]

(In reply to Matt Woodrow (:mattwoodrow) from comment #1)
> Adding avih and jmaher to the cc list since this is going to show up as a
> talos regression.

Do you know this for a fact? Last time I tried I couldn't notice overproduction IIRC with tscrollx (can't find the bug where I said it though, but I do recall roc was part of the conversation as well).

Comment 5

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/76d4e6230498

Comment 6

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

Matt, thanks for including us on this bug.  I see 3 regressions from this change:
10.8 tscrollx 339%
10.8 tart 9.2%
10.6 tscrollx 202%

as this change landed with 2 other patches (http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=f9c51223ffc9&tochange=76d4e6230498), it is possible that another patch caused the tart regression.

here is a graph for 10.6:
http://graphs.mozilla.org/graph.html#tests=[[287,63,21]]&sel=1407987418000,1408160218000&displayrange=7&datatype=running

Is this the expected behavior from this patch?

Comment 7

[Matt Woodrow (:mattwoodrow)]

Yeah that's expected, any test that uses ASAP mode would potentially be affected.

Comment 8

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

Thanks Matt, appreciate the heads up and reply!