[Intel-gfx] [RFC 4/4] drm/i915: Stop tracking execlists retired requests

[Chris Wilson]

On Fri, Apr 08, 2016 at 02:54:58PM +0100, Tvrtko Ursulin wrote:
> @@ -615,11 +613,6 @@ static void execlists_context_queue(struct drm_i915_gem_request *request)
>  	struct drm_i915_gem_request *cursor;
>  	int num_elements = 0;
>  
> -	if (request->ctx != request->i915->kernel_context)
> -		intel_lr_context_pin(request->ctx, engine);
> -
> -	i915_gem_request_reference(request);
> -
>  	spin_lock_bh(&engine->execlist_lock);
>  
>  	list_for_each_entry(cursor, &engine->execlist_queue, execlist_link)
> @@ -636,11 +629,12 @@ static void execlists_context_queue(struct drm_i915_gem_request *request)
>  		if (request->ctx == tail_req->ctx) {
>  			WARN(tail_req->elsp_submitted != 0,
>  				"More than 2 already-submitted reqs queued\n");
> -			list_move_tail(&tail_req->execlist_link,
> -				       &engine->execlist_retired_req_list);
> +			list_del(&tail_req->execlist_link);
> +			i915_gem_request_unreference(tail_req);
>  		}
>  	}
>  
> +	i915_gem_request_reference(request);
>  	list_add_tail(&request->execlist_link, &engine->execlist_queue);

If you want to get truly radical, we do not need the ref on the request
until it is submitted to hardware. (As the request cannot be retired
until it has done so, it can leave the execlist_queue until we commit it
to hw, or perform the cancel).

Lgtm,
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre