[Intel-gfx] [PATCH 17/70] drm/i915: Optimistically spin for the request completion

[Daniel Vetter]

On Mon, Apr 13, 2015 at 12:34:19PM +0100, Tvrtko Ursulin wrote:
> 
> Hi,
> 
> On 04/07/2015 04:20 PM, Chris Wilson wrote:
> >This provides a nice boost to mesa in swap bound scenarios (as mesa
> >throttles itself to the previous frame and given the scenario that will
> >complete shortly). It will also provide a good boost to systems running
> >with semaphores disabled and so frequently waiting on the GPU as it
> >switches rings. In the most favourable of microbenchmarks, this can
> >increase performance by around 15% - though in practice improvements
> >will be marginal and rarely noticeable.
> >
> >v2: Account for user timeouts
> >v3: Limit the spinning to a single jiffie (~1us) at most. On an
> >otherwise idle system, there is no scheduler contention and so without a
> >limit we would spin until the GPU is ready.
> >v4: Drop forcewake - the lazy coherent access doesn't require it, and we
> >have no reason to believe that the forcewake itself improves seqno
> >coherency - it only adds delay.
> >
> >Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> >Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> >Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> >Cc: Eero Tamminen <eero.t.tamminen at intel.com>
> >Cc: "Rantala, Valtteri" <valtteri.rantala at intel.com>
> 
> I already said that I already gave my r-b for this one. :)
> 
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Queued for -next, thanks for the patch.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch