[Intel-gfx] [PATCH 01/12] drm/i915: Split request submit/execute phase into two

[Tvrtko Ursulin]

On 02/11/2016 17:50, Chris Wilson wrote:
> In order to support deferred scheduling, we need to differentiate
> between when the request is ready to run (i.e. the submit fence is
> signaled) and when the request is actually run (a new execute fence).
> This is typically split between the request itself wanting to wait upon
> others (for which we use the submit fence) and the CPU wanting to wait
> upon the request, for which we use the execute fence to be sure the
> hardware is ready to signal completion.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_gem_request.c | 33 ++++++++++++++++++++++++---------
>  drivers/gpu/drm/i915/i915_gem_request.h |  2 ++
>  2 files changed, 26 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
> index 79b0046d9a57..1ae5a2f8953f 100644
> --- a/drivers/gpu/drm/i915/i915_gem_request.c
> +++ b/drivers/gpu/drm/i915/i915_gem_request.c
> @@ -351,11 +351,19 @@ submit_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
>  	list_move_tail(&request->link, &timeline->requests);
>  	spin_unlock(&request->timeline->lock);
>
> +	i915_sw_fence_commit(&request->execute);
> +
>  	spin_unlock_irqrestore(&timeline->lock, flags);
>
>  	return NOTIFY_DONE;
>  }
>
> +static int __i915_sw_fence_call
> +execute_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
> +{
> +	return NOTIFY_DONE;
> +}
> +
>  /**
>   * i915_gem_request_alloc - allocate a request structure
>   *
> @@ -441,6 +449,12 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
>  		       __timeline_get_seqno(req->timeline->common));
>
>  	i915_sw_fence_init(&req->submit, submit_notify);
> +	i915_sw_fence_init(&req->execute, execute_notify);
> +	/* Ensure that the execute fence completes after the submit fence -
> +	 * as we complete the execute fence from within the submit fence
> +	 * callback, its completion would otherwise be visible first.
> +	 */
> +	i915_sw_fence_await_sw_fence(&req->execute, &req->submit, &req->execq);
>
>  	INIT_LIST_HEAD(&req->active_list);
>  	req->i915 = dev_priv;
> @@ -817,9 +831,9 @@ bool __i915_spin_request(const struct drm_i915_gem_request *req,
>  }
>
>  static long
> -__i915_request_wait_for_submit(struct drm_i915_gem_request *request,
> -			       unsigned int flags,
> -			       long timeout)
> +__i915_request_wait_for_execute(struct drm_i915_gem_request *request,
> +				unsigned int flags,
> +				long timeout)
>  {
>  	const int state = flags & I915_WAIT_INTERRUPTIBLE ?
>  		TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
> @@ -831,9 +845,9 @@ __i915_request_wait_for_submit(struct drm_i915_gem_request *request,
>  		add_wait_queue(q, &reset);
>
>  	do {
> -		prepare_to_wait(&request->submit.wait, &wait, state);
> +		prepare_to_wait(&request->execute.wait, &wait, state);
>
> -		if (i915_sw_fence_done(&request->submit))
> +		if (i915_sw_fence_done(&request->execute))
>  			break;
>
>  		if (flags & I915_WAIT_LOCKED &&
> @@ -851,7 +865,7 @@ __i915_request_wait_for_submit(struct drm_i915_gem_request *request,
>
>  		timeout = io_schedule_timeout(timeout);
>  	} while (timeout);
> -	finish_wait(&request->submit.wait, &wait);
> +	finish_wait(&request->execute.wait, &wait);
>
>  	if (flags & I915_WAIT_LOCKED)
>  		remove_wait_queue(q, &reset);
> @@ -903,13 +917,14 @@ long i915_wait_request(struct drm_i915_gem_request *req,
>
>  	trace_i915_gem_request_wait_begin(req);
>
> -	if (!i915_sw_fence_done(&req->submit)) {
> -		timeout = __i915_request_wait_for_submit(req, flags, timeout);
> +	if (!i915_sw_fence_done(&req->execute)) {
> +		timeout = __i915_request_wait_for_execute(req, flags, timeout);
>  		if (timeout < 0)
>  			goto complete;
>
> -		GEM_BUG_ON(!i915_sw_fence_done(&req->submit));
> +		GEM_BUG_ON(!i915_sw_fence_done(&req->execute));
>  	}
> +	GEM_BUG_ON(!i915_sw_fence_done(&req->submit));
>  	GEM_BUG_ON(!req->global_seqno);
>
>  	/* Optimistic short spin before touching IRQs */
> diff --git a/drivers/gpu/drm/i915/i915_gem_request.h b/drivers/gpu/drm/i915/i915_gem_request.h
> index 75f8360b3421..ed13f37fea0f 100644
> --- a/drivers/gpu/drm/i915/i915_gem_request.h
> +++ b/drivers/gpu/drm/i915/i915_gem_request.h
> @@ -85,7 +85,9 @@ struct drm_i915_gem_request {
>  	struct intel_signal_node signaling;
>
>  	struct i915_sw_fence submit;
> +	struct i915_sw_fence execute;
>  	wait_queue_t submitq;
> +	wait_queue_t execq;
>
>  	u32 global_seqno;
>
>

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

Regards,

Tvrtko