1555343 - Always enable WR for Fission

Status: RESOLVED INVALID

(Core :: Graphics: WebRender, task, P3)

Description

[Neha Kochar [:neha]]

We would like to modify the WR enabling code to enable also if the fission pref is enabled, which is currently a per-window flag. Discussed offline with Ryan and he agreed that this is do-able. This will make Fission testing easier if all is tied to a single pref.

Comment 1

[Ryan Hunt [:rhunt] (on leave until early May)]

I was incorrect, there are not any plans to allow WR windows to co-exist with non-WR windows [1]. So we won't be able to only enable WR on windows that have fission enabled.

We could however enable WR for all windows if fission might be enabled for some windows. This depends on the fission enabling mechanism. If there's a master pref needed before possibly enabling fission for a window, then this is probably pretty straightforward.

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=1351384#c1

Comment 2

[Ryan Hunt [:rhunt] (on leave until early May)]

Trying to close the loop here from a conversation with Neha over irc.

My understanding of the situation is as follows:

1. The major feature we thought WR would support but non-WR wouldn't is hit testing, but it appears that WR and non-WR will both require hit testing work. Neither configuration is significantly better than the either in terms of fission support and both are suited for testing.
2. We don't support WR windows co-existing with non-WR windows, so we can't just enable WR in fission windows.
3. We want to be able to test non-WR with fission enabled, so we can't flip the webrender pref when the fission pref is enabled.

Neha, is there anything I missed? If not, it seems like there's not much graphics can do here.

Comment 3

[Neha Kochar [:neha]]

Henri, could you please test and check if hit testing works similarly with an without WR? If not, please file bugs for those under the meta "rendering-fission".

Comment 4

[Ryan Hunt [:rhunt] (on leave until early May)]

Even if we decide to have fission depending on webrender, it would be inconvenient to have the fission pref force-enable webrender as we may need to occasionally test fission without webrender. Putting both configuration changes under one pref would make it impossible to test without webrender enabled.

Comment 5

[Henri Sivonen (:hsivonen)]

(In reply to Neha Kochar [:neha] from comment #3)

Henri, could you please test and check if hit testing works similarly with an without WR? If not, please file bugs for those under the meta "rendering-fission".

It does not work properly without WR. Filed bug 1561858.

Comment 6

[Matt Woodrow (:mattwoodrow)]

Removing this from M4 as I don't think we want to do this in the near future.