Re: [PATCH i-g-t v2] tests/perf_pmu: Avoid RT thread for accuracy test

From: Chris Wilson <chris@chris-wilson.co.uk>
To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
	Tvrtko Ursulin <tursulin@ursulin.net>,
	igt-dev@lists.freedesktop.org
Cc: Intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH i-g-t v2] tests/perf_pmu: Avoid RT thread for accuracy test
Date: Tue, 03 Apr 2018 17:24:08 +0100	[thread overview]
Message-ID: <152277264848.32747.5978450744595739772@mail.alporthouse.com> (raw)
In-Reply-To: <0e9ca619-ac6b-ada1-cb2e-1cbbd8ae3170@linux.intel.com>

Quoting Tvrtko Ursulin (2018-04-03 17:09:09)
> 
> On 03/04/2018 14:10, Chris Wilson wrote:
> > To me it seems like the closed system with each loop being "spin then
> > adjusted sleep" will autocorrect and more likely to finish correct (as
> > we are less reliant on the next loop for the accuracy). It's pretty much
> > immaterial, as we expect the pmu to match the measurements (and not our
> > expectations), but I find the one pass does all much simpler to follow.
> 
> Since we do a good number of loops, and hope the calibration will 
> converge quickly (which it does for me), I don't see that there is an 
> issue there.

I'm sitting here drinking coffee trying to decide if it does converge ;)
That's the problem here, I need to actually find a pencil, some paper
and remember some basic maths for series convergence. Not happening with
the amount of coffee I need to drink at the moment.
-Chris
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