[Bug 35579] Poor performance in Firefox 4

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Sat Mar 26 01:42:05 PDT 2011


--- Comment #27 from Michel Dänzer <michel at daenzer.net> 2011-03-26 01:42:05 PDT ---
(In reply to comment #24)
> One way to hardware accelerate it would be to treat the texture as argb, but
> first copy the alpha channel of the border pixels somewhere else, then replace
> the alpha channel with 0xff, then copy the old alpha channel back.

Or keep a shadow picture. Are you volunteering? :)

(In reply to comment #25)
> But how come ShadowFB+noaccel is so much faster than fallback?

Alternating between hardware acceleration and software fallbacks incurs
GPU<->CPU synchronization and memory migration overhead.

(In reply to comment #26)
> Does the new generation hardware still have the source image size limits?

The texture size limits advertised via OpenGL or Direct3D usually reflect the
hardware capabilities.

> There must be something wrong with the driver, after all. That is to say, looks
> like the proprietary drivers optimize for this somehow

It's mostly a matter of (lack of) manpower to spend on such workarounds. At
least in this case, it seems like it should be easy for Firefox / cairo to
avoid the problem, which will also benefit already deployed X stacks.

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