Re: [PATCH 13/55] drm/i915: Add flag to i915_add_request() to skip the cache flush

[Tomas Elf <tomas.elf@intel.com>]

On 29/05/2015 17:43, John.C.Harrison@Intel.com wrote:
> From: John Harrison <John.C.Harrison@Intel.com>
>
> In order to explcitly track all GPU work (and completely remove the outstanding
> lazy request), it is necessary to add extra i915_add_request() calls to various
> places. Some of these do not need the implicit cache flush done as part of the
> standard batch buffer submission process.
>
> This patch adds a flag to _add_request() to specify whether the flush is
> required or not.
>
> For: VIZ-5115
> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
> ---
>   drivers/gpu/drm/i915/i915_drv.h              |    7 +++++--
>   drivers/gpu/drm/i915/i915_gem.c              |   17 ++++++++++-------
>   drivers/gpu/drm/i915/i915_gem_execbuffer.c   |    2 +-
>   drivers/gpu/drm/i915/i915_gem_render_state.c |    2 +-
>   drivers/gpu/drm/i915/intel_lrc.c             |    2 +-
>   5 files changed, 18 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index cc2c45c..f5a733b 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2863,9 +2863,12 @@ int __must_check i915_gpu_idle(struct drm_device *dev);
>   int __must_check i915_gem_suspend(struct drm_device *dev);
>   void __i915_add_request(struct intel_engine_cs *ring,
>   			struct drm_file *file,
> -			struct drm_i915_gem_object *batch_obj);
> +			struct drm_i915_gem_object *batch_obj,
> +			bool flush_caches);
>   #define i915_add_request(ring) \
> -	__i915_add_request(ring, NULL, NULL)
> +	__i915_add_request(ring, NULL, NULL, true)
> +#define i915_add_request_no_flush(ring) \
> +	__i915_add_request(ring, NULL, NULL, false)
>   int __i915_wait_request(struct drm_i915_gem_request *req,
>   			unsigned reset_counter,
>   			bool interruptible,
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index ba2e7f7..458b54e 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2470,7 +2470,8 @@ i915_gem_get_seqno(struct drm_device *dev, u32 *seqno)
>    */
>   void __i915_add_request(struct intel_engine_cs *ring,
>   			struct drm_file *file,
> -			struct drm_i915_gem_object *obj)
> +			struct drm_i915_gem_object *obj,
> +			bool flush_caches)
>   {
>   	struct drm_i915_private *dev_priv = ring->dev->dev_private;
>   	struct drm_i915_gem_request *request;
> @@ -2502,12 +2503,14 @@ void __i915_add_request(struct intel_engine_cs *ring,
>   	 * is that the flush _must_ happen before the next request, no matter
>   	 * what.
>   	 */
> -	if (i915.enable_execlists)
> -		ret = logical_ring_flush_all_caches(ringbuf, request->ctx);
> -	else
> -		ret = intel_ring_flush_all_caches(ring);
> -	/* Not allowed to fail! */
> -	WARN(ret, "*_ring_flush_all_caches failed: %d!\n", ret);
> +	if (flush_caches) {
> +		if (i915.enable_execlists)
> +			ret = logical_ring_flush_all_caches(ringbuf, request->ctx);
> +		else
> +			ret = intel_ring_flush_all_caches(ring);
> +		/* Not allowed to fail! */
> +		WARN(ret, "*_ring_flush_all_caches failed: %d!\n", ret);
> +	}
>
>   	/* Record the position of the start of the request so that
>   	 * should we detect the updated seqno part-way through the
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index a6532db..e27f47f 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1058,7 +1058,7 @@ i915_gem_execbuffer_retire_commands(struct i915_execbuffer_params *params)
>   	params->ring->gpu_caches_dirty = true;
>
>   	/* Add a breadcrumb for the completion of the batch buffer */
> -	__i915_add_request(params->ring, params->file, params->batch_obj);
> +	__i915_add_request(params->ring, params->file, params->batch_obj, true);
>   }
>
>   static int
> diff --git a/drivers/gpu/drm/i915/i915_gem_render_state.c b/drivers/gpu/drm/i915/i915_gem_render_state.c
> index ce4788f..4418616 100644
> --- a/drivers/gpu/drm/i915/i915_gem_render_state.c
> +++ b/drivers/gpu/drm/i915/i915_gem_render_state.c
> @@ -173,7 +173,7 @@ int i915_gem_render_state_init(struct intel_engine_cs *ring)
>
>   	i915_vma_move_to_active(i915_gem_obj_to_ggtt(so.obj), ring);
>
> -	__i915_add_request(ring, NULL, so.obj);
> +	__i915_add_request(ring, NULL, so.obj, true);
>   	/* __i915_add_request moves object to inactive if it fails */
>   out:
>   	i915_gem_render_state_fini(&so);
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 6c0b16f..00bb335 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -1371,7 +1371,7 @@ static int intel_lr_context_render_state_init(struct intel_engine_cs *ring,
>
>   	i915_vma_move_to_active(i915_gem_obj_to_ggtt(so.obj), ring);
>
> -	__i915_add_request(ring, file, so.obj);
> +	__i915_add_request(ring, file, so.obj, true);
>   	/* intel_logical_ring_add_request moves object to inactive if it
>   	 * fails */
>   out:
>


Reviewed-by: Tomas Elf <tomas.elf@intel.com>

Thanks,
Tomas

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