[Intel-gfx] [PATCH 2/3] drm/i915/gem: Treat submit-fence as weak dependency for new clients

[Tvrtko Ursulin]

On 07/05/2020 09:21, Chris Wilson wrote:
> The submit-fence adds a weak dependency to the requests, and for the
> purpose of our FQ_CODEL hinting we do not want to treat as a
> restriction. This is primarily because clients may treat submit-fences
> as a bidirectional bonding between a pair of co-ordinating requests.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>   drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 13 ++++++++++++-
>   1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> index 966523a8503f..e8bf0cf02fd7 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> @@ -2565,6 +2565,17 @@ static void retire_requests(struct intel_timeline *tl, struct i915_request *end)
>   			break;
>   }
>   
> +static bool new_client(struct i915_request *rq)
> +{
> +	struct i915_dependency *p;
> +
> +	list_for_each_entry(p, &rq->sched.signalers_list, signal_link)
> +		if (!(p->flags & I915_DEPENDENCY_WEAK))
> +			return false;
> +
> +	return true;
> +}
> +
>   static void eb_request_add(struct i915_execbuffer *eb)
>   {
>   	struct i915_request *rq = eb->request;
> @@ -2604,7 +2615,7 @@ static void eb_request_add(struct i915_execbuffer *eb)
>   		 * Allow interactive/synchronous clients to jump ahead of
>   		 * the bulk clients. (FQ_CODEL)
>   		 */
> -		if (list_empty(&rq->sched.signalers_list))
> +		if (new_client(rq))
>   			attr.priority |= I915_PRIORITY_WAIT;
>   	} else {
>   		/* Serialise with context_close via the add_to_timeline */
> 

Did absence of this have any functional effect? I hope not, but anyway:

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

Regards,

Tvrtko