Audio Skips when Scrolling in Firefox

Michel Dänzer michel at
Fri Apr 20 10:35:26 PDT 2007

On Fri, 2007-04-20 at 13:10 -0400, Andrew J. Barr wrote:
> Michel Dänzer wrote:
> >> Strictly relevant to this list, however, is that a good portion (2nd on
> >> the list) of the CPU's time while scrolling in Fx is spent in
> >> in glxFillAlphaChannel.
> > 
> > That means my patches aren't fully effective, as that function is only
> > called in the !override case. You are using EXA and making sure it has
> > enough offscreen memory available, aren't you?
> I am using EXA. I'm assuming at least in the case of the radeon driver
> the way to specify the offscreen memory amount is using the
> "FBTexPercent" option?


> What is the recommended value there (128 MB VRAM in this machine) and is
> it different depending on if you are using a GLX compositing manager or
> not? I have it set at 100, which is either really bad or really good, I
> suspect... :P

It means all offscreen memory is reserved for GL textures and none for
EXA. That's bad in this case, as the purpose of my patches is to point
the 3D driver to EXA offscreen memory directly (instead of reading the
pixels from the pixmap, passing them to glTexSubImage, which results in
the 3D driver  re-uploading the whole texture to the GL portion of
offscreen memory after a couple of copies). 20 seems a good value for my
workload on the same machine, YMMV. (Note that the r300 3D driver won't
work correctly with 0).

Earthling Michel Dänzer           |
Libre software enthusiast         |          Debian, X and DRI developer

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