[Intel-gfx] [PATCH v2 3/3] drm/i915: optimise intel_runtime_pm_{get, put}

[Ville Syrjälä]

On Fri, Nov 18, 2016 at 02:00:40PM +0000, Chris Wilson wrote:
> On Fri, Nov 18, 2016 at 03:36:47PM +0200, David Weinehall wrote:
> > Benchmarking shows that on resume we spend quite a bit of time
> > just taking and dropping these references, leaving us two options;
> > either rewriting the code not to take these references more than
> > once, which would be a rather invasive change since the involved
> > functions are used from other places, or to optimise
> > intel_runtime_pm_{get,put}().  This patch does the latter.
> > Initial benchmarking indicate improvements of a couple
> > of milliseconds on resume.
> > 
> > Original patch by Chris, with slight fixes by me.
> > 
> > v2: Fix missing return value (Patchwork)
> >     Remove extra atomic_dec() (Chris)
> > 
> > Signed-off-by: David Weinehall <david.weinehall at linux.intel.com>
> > CC: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Imre Deak <imre.deak at linux.intel.com>
> 
> I'm happy with this. Not amused that it apparently saves quite a bit of
> overhead with frequent pm_runtime calls.

We could eliminate some of those calls entirely by moving them from
intel_display_power_{get,put}() into the always on well enable/disable
hooks. But I'm not sure how much this overhead originates from the power
well code as opposed to some gem/etc. stuff.

> 
> Imre?
> -Chris
> 
> -- 
> Chris Wilson, Intel Open Source Technology Centre
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel OTC