[Intel-gfx] [PATCH 8/8] drm/i915: Improve GuC request coalescing

[Michał Winiarski]

On Wed, Sep 20, 2017 at 05:37:05PM +0300, Mika Kuoppala wrote:
> Now that we can keep track of what ports we have
> dequeued, coalesce only those ports instead of iterating
> through all ports.

s/coalesce/submit.

By coalescing I meant that we're no longer have a 1:1 relationship between a
request and GuC workitem. But we're doing that in guc_dequeue by keeping the
request-to-be-turned-into-workitem in port.

> 
> Cc: Michał Winiarski <michal.winiarski at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_guc_submission.c | 31 +++++++++++++++++-------------
>  drivers/gpu/drm/i915/intel_ringbuffer.h    |  9 +++++++++
>  2 files changed, 27 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
> index 359f57a59cba..1057a0fb9f27 100644
> --- a/drivers/gpu/drm/i915/i915_guc_submission.c
> +++ b/drivers/gpu/drm/i915/i915_guc_submission.c
> @@ -485,11 +485,13 @@ static void guc_ring_doorbell(struct i915_guc_client *client)
>  /**
>   * i915_guc_submit() - Submit commands through GuC
>   * @engine: engine associated with the commands
> + * @first: index of first execlist port to start coalescing from

s/coalescing/submitting

Reviewed-by: Michał Winiarski <michal.winiarski at intel.com>

-Michał

>   *
>   * The only error here arises if the doorbell hardware isn't functioning
>   * as expected, which really shouldn't happen.
>   */
> -static void i915_guc_submit(struct intel_engine_cs *engine)
> +static void i915_guc_submit(struct intel_engine_cs *engine,
> +			    const unsigned int first)
>  {
>  	struct drm_i915_private *dev_priv = engine->i915;
>  	struct intel_guc *guc = &dev_priv->guc;
> @@ -498,7 +500,7 @@ static void i915_guc_submit(struct intel_engine_cs *engine)
>  	const unsigned int engine_id = engine->id;
>  	unsigned int n;
>  
> -	for (n = 0; n < execlist_active_ports(el); n++) {
> +	for (n = first; n < execlist_active_ports(el); n++) {
>  		struct execlist_port *port;
>  		struct drm_i915_gem_request *rq;
>  		unsigned int count;
> @@ -506,21 +508,22 @@ static void i915_guc_submit(struct intel_engine_cs *engine)
>  		port = execlist_port_index(el, n);
>  
>  		rq = port_unpack(port, &count);
> -		if (rq && count == 0) {
> -			port_set(port, port_pack(rq, ++count));
> +		GEM_BUG_ON(!rq);
> +		GEM_BUG_ON(count);
>  
> -			if (i915_vma_is_map_and_fenceable(rq->ring->vma))
> -				POSTING_READ_FW(GUC_STATUS);
> +		port_set(port, port_pack(rq, ++count));
>  
> -			spin_lock(&client->wq_lock);
> +		if (i915_vma_is_map_and_fenceable(rq->ring->vma))
> +			POSTING_READ_FW(GUC_STATUS);
>  
> -			guc_wq_item_append(client, rq);
> -			guc_ring_doorbell(client);
> +		spin_lock(&client->wq_lock);
>  
> -			client->submissions[engine_id] += 1;
> +		guc_wq_item_append(client, rq);
> +		guc_ring_doorbell(client);
>  
> -			spin_unlock(&client->wq_lock);
> -		}
> +		client->submissions[engine_id] += 1;
> +
> +		spin_unlock(&client->wq_lock);
>  	}
>  }
>  
> @@ -566,6 +569,7 @@ static void i915_guc_dequeue(struct intel_engine_cs *engine)
>  	struct drm_i915_gem_request *last = NULL;
>  	bool submit = false;
>  	struct rb_node *rb;
> +	unsigned int first_idx;
>  
>  	spin_lock_irq(&engine->timeline->lock);
>  	rb = el->first;
> @@ -575,6 +579,7 @@ static void i915_guc_dequeue(struct intel_engine_cs *engine)
>  		goto done;
>  
>  	port = execlist_request_port(el);
> +	first_idx = execlist_get_port_index(el, port);
>  
>  	do {
>  		struct i915_priolist *p = rb_entry(rb, typeof(*p), node);
> @@ -614,7 +619,7 @@ static void i915_guc_dequeue(struct intel_engine_cs *engine)
>  	el->first = rb;
>  	if (submit) {
>  		port_assign(port, last);
> -		i915_guc_submit(engine);
> +		i915_guc_submit(engine, first_idx);
>  	}
>  	spin_unlock_irq(&engine->timeline->lock);
>  }
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
> index efa5a8ea1ecb..f2eb32539300 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
> @@ -556,6 +556,15 @@ execlist_port_index(struct intel_engine_execlist * const el,
>  	return &el->port[__port_idx(el->port_head, n, el->port_mask)];
>  }
>  
> +static inline unsigned int
> +execlist_get_port_index(const struct intel_engine_execlist * const el,
> +			const struct execlist_port * const port)
> +{
> +	const unsigned int n = port_index(port, el);
> +
> +	return __port_idx(n, -el->port_head, el->port_mask);
> +}
> +
>  static inline struct execlist_port *
>  execlist_port_head(struct intel_engine_execlist * const el)
>  {
> -- 
> 2.11.0
>