Re: [igt-dev] [PATCH i-g-t] tests/kms_flip: Allow an extra half frame for vblank waits

Chris Wilson
2019-10-30T18:08:16Z

Quoting Ville Syrjala (2019-10-30 18:01:44)
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> The vblank tests try to make sure a relative vblank wait of
> 2 counts completes in ~1-2 frames (depends on how far along the
> first frame we are when initiating the wait). The actual
> limits we check are 0.9 to 2.1 frames to account for inaccuracies
> in the reported dotclock. Unfortunately it seems we either
> have even more inaccurate dotclocks or scheduling latencies
> and whatnot are pushing that out quite a bit further. So let's
> extend the end limit to ~2.6 frames to cut down on the noise a bit.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111609
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

I thought you were crazy, but upon checking we are looking at walltime
and not the vblank interrupt timestamp.

.5 frames is ~8ms, so quite understandable for scheduling latency of the
igt itself. Probably it was that java hog...

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
-Chris