[Intel-gfx] [PATCH igt] igt/gem_exec_latency: Wire up an interloper for preemption

[Chris Wilson]

Quoting Michał Winiarski (2017-10-26 11:52:31)
> On Thu, Oct 26, 2017 at 08:31:27AM +0100, Chris Wilson wrote:
> > For measuring the cost of preemption, inject a low priority spinner
> > between the two measurements; the difference between the preemption and
> > the normal dispatch includes both the cost of the spinner dispatch and
> > of preempting it. Close enough for us to estimate the cost of
> > preemption, though we don't measure the cost of preemption on the local
> > ring!
> 
> And as expected, we're seeing more delay with GuC, probably from worker
> scheduling delay (~2ms on my SKL if I'm reading the results correctly).
> 
> Reviewed-by: Michał Winiarski <michal.winiarski at intel.com>

And I forgot to copy'n'paste the r-b before pushing. The inquisition
will be calling shortly.

I was going to say, no reason to hold back on pushing this, as this is
a benchmark for our informational purposes only. One day, it shall be
moved to benchmarks/
-Chris