[PATCH] sna: avoid negative timeouts

[Chris Wilson]

On Thu, Oct 03, 2013 at 01:29:29AM -0500, Felipe Contreras wrote:
> It's nice to avoid X server crashes (by not passing negative values to
> select(3)).
> 
> For more information:
> http://article.gmane.org/gmane.comp.freedesktop.xorg.devel/37388
> 
> Signed-off-by: Felipe Contreras <felipe.contreras at gmail.com>

Thanks for the patch, I pushed a slightly different version to consume
the expired flush timeout immediately.

However, in order for this to happen something within the BlockHandler
must have run for at least 4ms. Which is itself very worrying - the two
candidates are the throttle or lock contention. (The throttle is also
prone to being influenced by a third party.) Such stalls are likely to
be noticeable as jitter or judder, so if you can spot their source
hopefully we can tackle the root cause.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre