[Intel-gfx] [PATCH 04/29] drm/i915: Consolidate the timeline->barrier

[Tvrtko Ursulin]

On 08/04/2019 10:17, Chris Wilson wrote:
> The timeline is strictly ordered, so by inserting the timeline->barrier
> request into the timeline->last_request it naturally provides the same
> barrier. Consolidate the pair of barriers into one as they serve the
> same purpose.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_gem_context.c        | 13 ++-----------
>   drivers/gpu/drm/i915/i915_request.c            |  9 ---------
>   drivers/gpu/drm/i915/i915_timeline.c           |  2 --
>   drivers/gpu/drm/i915/i915_timeline.h           | 15 ---------------
>   drivers/gpu/drm/i915/i915_timeline_types.h     | 10 ----------
>   drivers/gpu/drm/i915/selftests/mock_timeline.c |  1 -
>   6 files changed, 2 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index 66b6852cb4d2..7fc34ab6df87 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -1167,7 +1167,7 @@ static int
>   gen8_modify_rpcs(struct intel_context *ce, struct intel_sseu sseu)
>   {
>   	struct drm_i915_private *i915 = ce->engine->i915;
> -	struct i915_request *rq, *prev;
> +	struct i915_request *rq;
>   	intel_wakeref_t wakeref;
>   	int ret;
>   
> @@ -1192,16 +1192,7 @@ gen8_modify_rpcs(struct intel_context *ce, struct intel_sseu sseu)
>   	}
>   
>   	/* Queue this switch after all other activity by this context. */
> -	prev = i915_active_request_raw(&ce->ring->timeline->last_request,
> -				       &i915->drm.struct_mutex);
> -	if (prev && !i915_request_completed(prev)) {
> -		ret = i915_request_await_dma_fence(rq, &prev->fence);
> -		if (ret < 0)
> -			goto out_add;
> -	}
> -
> -	/* Order all following requests to be after. */
> -	ret = i915_timeline_set_barrier(ce->ring->timeline, rq);
> +	ret = i915_active_request_set(&ce->ring->timeline->last_request, rq);
>   	if (ret)
>   		goto out_add;
>   
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 2da0d6436a1a..96a9e8bcd805 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -584,11 +584,6 @@ i915_request_alloc_slow(struct intel_context *ce)
>   	return kmem_cache_alloc(global.slab_requests, GFP_KERNEL);
>   }
>   
> -static int add_timeline_barrier(struct i915_request *rq)
> -{
> -	return i915_request_await_active_request(rq, &rq->timeline->barrier);
> -}
> -
>   /**
>    * i915_request_alloc - allocate a request structure
>    *
> @@ -738,10 +733,6 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
>   	 */
>   	rq->head = rq->ring->emit;
>   
> -	ret = add_timeline_barrier(rq);
> -	if (ret)
> -		goto err_unwind;
> -
>   	ret = engine->request_alloc(rq);
>   	if (ret)
>   		goto err_unwind;
> diff --git a/drivers/gpu/drm/i915/i915_timeline.c b/drivers/gpu/drm/i915/i915_timeline.c
> index 2f4907364920..5fbea0892f33 100644
> --- a/drivers/gpu/drm/i915/i915_timeline.c
> +++ b/drivers/gpu/drm/i915/i915_timeline.c
> @@ -253,7 +253,6 @@ int i915_timeline_init(struct drm_i915_private *i915,
>   	spin_lock_init(&timeline->lock);
>   	mutex_init(&timeline->mutex);
>   
> -	INIT_ACTIVE_REQUEST(&timeline->barrier);
>   	INIT_ACTIVE_REQUEST(&timeline->last_request);
>   	INIT_LIST_HEAD(&timeline->requests);
>   
> @@ -326,7 +325,6 @@ void i915_timeline_fini(struct i915_timeline *timeline)
>   {
>   	GEM_BUG_ON(timeline->pin_count);
>   	GEM_BUG_ON(!list_empty(&timeline->requests));
> -	GEM_BUG_ON(i915_active_request_isset(&timeline->barrier));
>   
>   	i915_syncmap_free(&timeline->sync);
>   
> diff --git a/drivers/gpu/drm/i915/i915_timeline.h b/drivers/gpu/drm/i915/i915_timeline.h
> index 4ca7f80bdf6d..27668a1a69a3 100644
> --- a/drivers/gpu/drm/i915/i915_timeline.h
> +++ b/drivers/gpu/drm/i915/i915_timeline.h
> @@ -110,19 +110,4 @@ void i915_timelines_init(struct drm_i915_private *i915);
>   void i915_timelines_park(struct drm_i915_private *i915);
>   void i915_timelines_fini(struct drm_i915_private *i915);
>   
> -/**
> - * i915_timeline_set_barrier - orders submission between different timelines
> - * @timeline: timeline to set the barrier on
> - * @rq: request after which new submissions can proceed
> - *
> - * Sets the passed in request as the serialization point for all subsequent
> - * submissions on @timeline. Subsequent requests will not be submitted to GPU
> - * until the barrier has been completed.
> - */
> -static inline int
> -i915_timeline_set_barrier(struct i915_timeline *tl, struct i915_request *rq)
> -{
> -	return i915_active_request_set(&tl->barrier, rq);
> -}
> -
>   #endif
> diff --git a/drivers/gpu/drm/i915/i915_timeline_types.h b/drivers/gpu/drm/i915/i915_timeline_types.h
> index 1f5b55d9ffb5..5256a0b5c5f7 100644
> --- a/drivers/gpu/drm/i915/i915_timeline_types.h
> +++ b/drivers/gpu/drm/i915/i915_timeline_types.h
> @@ -61,16 +61,6 @@ struct i915_timeline {
>   	 */
>   	struct i915_syncmap *sync;
>   
> -	/**
> -	 * Barrier provides the ability to serialize ordering between different
> -	 * timelines.
> -	 *
> -	 * Users can call i915_timeline_set_barrier which will make all
> -	 * subsequent submissions to this timeline be executed only after the
> -	 * barrier has been completed.
> -	 */
> -	struct i915_active_request barrier;
> -
>   	struct list_head link;
>   	struct drm_i915_private *i915;
>   
> diff --git a/drivers/gpu/drm/i915/selftests/mock_timeline.c b/drivers/gpu/drm/i915/selftests/mock_timeline.c
> index 416d85233263..e084476469ef 100644
> --- a/drivers/gpu/drm/i915/selftests/mock_timeline.c
> +++ b/drivers/gpu/drm/i915/selftests/mock_timeline.c
> @@ -16,7 +16,6 @@ void mock_timeline_init(struct i915_timeline *timeline, u64 context)
>   	spin_lock_init(&timeline->lock);
>   	mutex_init(&timeline->mutex);
>   
> -	INIT_ACTIVE_REQUEST(&timeline->barrier);
>   	INIT_ACTIVE_REQUEST(&timeline->last_request);
>   	INIT_LIST_HEAD(&timeline->requests);
>   
> 

Modulo the persistently impenetrable sw fence await flavours, this is 
indeed the same. I guess it goes under the thinking outside the box 
category, tracking a foreign context request on a different timeline.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko