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From: Chris Wilson <chris@chris-wilson.co.uk>
To: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH] drm/i915/selftests: Measure CS_TIMESTAMP
Date: Tue, 19 May 2020 11:46:54 +0100	[thread overview]
Message-ID: <158988521466.7442.3791653477981759222@build.alporthouse.com> (raw)
In-Reply-To: <20200519104245.GV6112@intel.com>

Quoting Ville Syrjälä (2020-05-19 11:42:45)
> On Sat, May 16, 2020 at 02:31:02PM +0100, Chris Wilson wrote:
> > Count the number of CS_TIMESTAMP ticks and check that it matches our
> > expectations.
> 
> Looks ok for everything except g4x/ilk. Those would need something
> like
> https://patchwork.freedesktop.org/patch/355944/?series=74145&rev=1
> + read TIMESTAMP_UDW instead of TIMESTAMP.
> 
> bw/cl still needs
> https://patchwork.freedesktop.org/patch/355946/?series=74145&rev=1
> though the test seems a bit flaky on my cl. Sometimes the cycle count
> comes up short. Never seen it exceed the expected value, but it can 
> come up significantly short. And curiously it does seem to have a
> tendency to come out as roughly some nice fraction (seen at least
> 1/2 and 1/4 quite a few times). Dunno if the tick rate actually
> changes due to some unknown circumstances, or if the counter just
> updates somehow lazily. Certainly polling the counter over a longer
> period does show it to tick at the expected rate.

Any guestimate at how short a period is long enough?
-Chris
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  reply	other threads:[~2020-05-19 10:47 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-16 13:24 [Intel-gfx] [PATCH] drm/i915/selftests: Measure CS_TIMESTAMP Chris Wilson
2020-05-16 13:31 ` Chris Wilson
2020-05-18  9:18   ` Chris Wilson
2020-05-19 10:42   ` Ville Syrjälä
2020-05-19 10:46     ` Chris Wilson [this message]
2020-05-19 11:47       ` Ville Syrjälä
2020-05-18  8:16 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for drm/i915/selftests: Measure CS_TIMESTAMP (rev2) Patchwork
2020-05-18  8:39 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork
2020-05-19 12:36 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for drm/i915/selftests: Measure CS_TIMESTAMP (rev3) Patchwork
2020-05-19 12:59 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork

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