[Bug 99418] DRI3 Stuttering while scrolling in Chromium/Chrome with VBLANK off

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=99418

--- Comment #32 from Michel Dänzer <michel at daenzer.net> ---
(In reply to lei.pero from comment #31)
> It's still odd behaviour, in both cases Chrome caps FPS to refresh rate (this
> case 85FPS),

Sounds like Chrome just has its own framerate throttling which works
independently from sync-to-vblank.


> but using DRI3 using mutter/clutter, for some reason it creates
> continuous stutters, even tho FPS is the same and all other parameters are
> equal. It really looks (when viewed live) as if FPS is not equal to refresh
> rate.

It's possible that the mutter framerate doesn't match the refresh rate (you can
check by setting GALLIUM_HUD=fps for the mutter process), but it's also
possible it's simply due to unfortunate interaction between the Chrome and
mutter frame timings.


> [...] it is still probably mutter/clutter configuration problem in the code
> (since it happens only there), it doesn't follow configuration in .drirc as
> other WM's.

Not really. By setting vblank_mode=0, you're forcing mutter to run in a way it
doesn't intend. If doing so breaks something, that can hardly be considered a
mutter bug, and you get to keep all the pieces. :)

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