Intel i915 / GEM throttling / 2.6.31-rc

[Michał Kazior]

Hello,

Since the inclusion of a GEM throttling commit [1] to the 2.6.31
release candidate I started to have serious issues using 3D
acceleration.

3D Applications which are rather simple tend to render themselves in
bursts (i.e. shows a dozen of frames and then freezes for a split of a
second; repeat). I've filed a bug at kernel bug [2], but now I'm
starting to think it might be (also) xserver issue.

Recently I noticed a detail which led me here. Stepmania [3] is one of
those suffering applications. The interesting part I noticed is that
it can render perfectly fine when the game window does not have
keyboard focus. If it regains the focus/input - it starts to render in
those bursts again. Quake3-demo and glxgears on the other hand render
in bursts regardless of the input/focus. It doesn't seem to be WM
related too.

I thought it might an unintentional sync to the swap or something, but
the relation to keyboard focus makes it kind of.. illogical ?

Are you guys aware of this issue ? Any other thoughts ?


Regards,
Michał Kazior.


[1]: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b962442e46a9340bdbc6711982c59ff0cc2b5afb
[2]: http://bugzilla.kernel.org/show_bug.cgi?id=13713
[3]: http://www.stepmania.com/