1899405 - systemui spends a bunch of time painting gradients during page load (probably progress bar)

Status: NEW

(Firefox for Android :: Performance, defect)

Description

[Jeff Muizelaar [:jrmuizel]]

I see this when launching Fenix to https://nos.nl. See https://share.firefox.dev/3V3inWe. The gradient painting is happening in neon_and_crc32::lowp::gradient()

I don't see this happening when launching Chrome.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:bhood, could you have a look please?

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Comment 2

[Jeff Muizelaar [:jrmuizel]]

I don't think this is a graphics bug, it's more likely something the Fenix front end is doing that's causing the extra work in the systemui process.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:amejia, could you have a look please?

For more information, please visit BugBot documentation.

Comment 4

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:kaya, could you have a look please?

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Comment 5

[Markus Stange [:mstange]]

Jeff, can you check if this still happens now that the toolbar shadow was removed (at least in the configuration where the navbar is present) in bug 1889739? If it's still there, then it's probably the progress bar and not the shadow that's causing this cost.

Comment 6

[Jeff Muizelaar [:jrmuizel]]

Can someone gather a new profile?

Comment 7

[Markus Stange [:mstange]]

Recent profile: https://share.firefox.dev/4h7CPhJ

Yes, it's still happening. My guess is that something is triggering frequent redraws of the Fenix progress bar.

Comment 8

[Markus Stange [:mstange]]

Jeff dug into this a little bit more but we haven't really found out what causes this.

One hypothesis was that we might be calling the .progress setting too frequently.
This hypothesis seems to be false: We're not calling it frequently enough to explain the system UI load. Jeff had a profile with markers in the setter.

Another hypothesis is that constant repainting is just how ProgressBar works, because it has the ability to be animated between values and it doesn't check whether it actually needs to repaint. But this is pure speculation, we haven't read the code to find out how it decides whether it needs a repaint.