[Intel-gfx] [PATCH 2/3] drm/i915: Bump GT idling delay to 2 jiffies

[Rodrigo Vivi]

On Tue, Jul 05, 2022 at 12:57:18PM +0200, Karolina Drobnik wrote:
> From: Chris Wilson <chris at chris-wilson.co.uk>
> 
> In monitoring a transcode pipeline that is latency sensitive (it waits
> between submitting frames, and each frame requires work on rcs/vcs/vecs
> engines), it is found that it took longer than a single jiffy for it to
> sustain its workload. Allowing an extra jiffy headroom for the userspace
> prevents us from prematurely parking and having to exit powersaving
> immediately.
> 
> Link: https://gitlab.freedesktop.org/drm/intel/-/issues/6284
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Karolina Drobnik <karolina.drobnik at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_active.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c
> index ee2b3a375362..7412abf166a8 100644
> --- a/drivers/gpu/drm/i915/i915_active.c
> +++ b/drivers/gpu/drm/i915/i915_active.c
> @@ -974,7 +974,7 @@ void i915_active_acquire_barrier(struct i915_active *ref)
>  
>  		GEM_BUG_ON(!intel_engine_pm_is_awake(engine));
>  		llist_add(barrier_to_ll(node), &engine->barrier_tasks);
> -		intel_engine_pm_put_delay(engine, 1);
> +		intel_engine_pm_put_delay(engine, 2);

I believe we should make more use of the runtime_idle to check for some
pending activity like this... but in the current structure this patch seems
the best and easiest option.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

>  	}
>  }
>  
> -- 
> 2.25.1
>