From: Chris Wilson <chris@chris-wilson.co.uk>
To: intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH v3] drm/i915/display: Record the plane update times for debugging
Date: Wed, 02 Dec 2020 22:12:42 +0000 [thread overview]
Message-ID: <160694716274.26639.17366834597602784251@build.alporthouse.com> (raw)
In-Reply-To: <20201202212814.26320-1-chris@chris-wilson.co.uk>
Quoting Chris Wilson (2020-12-02 21:28:14)
> Since we try and estimate how long we require to update the registers to
> perform a plane update, it is of vital importance that we measure the
> distribution of plane updates to better guide our estimate. If we
> underestimate how long it takes to perform the plane update, we may
> slip into the next scanout frame causing a tear. If we overestimate, we
> may unnecessarily delay the update to the next frame, causing visible
> jitter.
>
> Replace the warning that we exceed some arbitrary threshold for the
> vblank update with a histogram for debugfs.
>
> v2: Add a per-crtc debugfs entry so that the information is easier to
> extract when testing individual CRTC, and so that it can be reset before
> a test.
>
> v3: Flip the graph on its side; creates space to label the time axis.
>
> Updates: 4684
> |
> 1us |
> |
> 4us |********
> |**********
> 16us |***********
> |*****
> 66us |
> |
> 262us |
> |
> 1ms |
> |
> 4ms |
> |
> 17ms |
> |
> Min update: 5918ns
> Max update: 54781ns
> Average update: 16628ns
> Overruns > 250us: 0
>
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/1982
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> #v2
-Chris
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next prev parent reply other threads:[~2020-12-02 22:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-02 21:28 [Intel-gfx] [PATCH v3] drm/i915/display: Record the plane update times for debugging Chris Wilson
2020-12-02 22:12 ` Chris Wilson [this message]
2020-12-02 22:18 ` [Intel-gfx] ✓ Fi.CI.BAT: success for drm/i915/display: Record the plane update times for debugging (rev10) Patchwork
2020-12-03 0:33 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
-- strict thread matches above, loose matches on Subject: below --
2020-12-02 21:28 [Intel-gfx] [PATCH v3] drm/i915/display: Record the plane update times for debugging Chris Wilson
2020-12-03 12:45 ` Ville Syrjälä
2020-12-03 12:53 ` Chris Wilson
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