[Intel-gfx] [PATCH v3] drm/i915: Optimistically spin for the request completion

[Tvrtko Ursulin]

On 03/12/2015 11:11 AM, 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.

Isn't one jiffie 1-10ms typically?

Regards,

Tvrtko