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[04/71] drm/i915: Keep one request in our ring_list

Message ID 20180503063757.22238-4-chris@chris-wilson.co.uk (mailing list archive)
State New, archived
Headers show

Commit Message

Chris Wilson May 3, 2018, 6:36 a.m. UTC
Don't pre-emptively retire the oldest request in our ring's list if it
is the only request. We keep various bits of state alive using the
active reference from the request and would rather transfer that state
over to a new request rather than the more involved process of retiring
and reacquiring it.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_request.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Tvrtko Ursulin May 3, 2018, 5:04 p.m. UTC | #1
On 03/05/2018 07:36, Chris Wilson wrote:
> Don't pre-emptively retire the oldest request in our ring's list if it
> is the only request. We keep various bits of state alive using the
> active reference from the request and would rather transfer that state
> over to a new request rather than the more involved process of retiring
> and reacquiring it.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_request.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 5acf869f3ca3..75061f9e48eb 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -694,9 +694,9 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
>   		goto err_unreserve;
>   
>   	/* Move our oldest request to the slab-cache (if not in use!) */
> -	rq = list_first_entry_or_null(&ring->request_list,
> -				      typeof(*rq), ring_link);
> -	if (rq && i915_request_completed(rq))
> +	rq = list_first_entry(&ring->request_list, typeof(*rq), ring_link);
> +	if (!list_is_last(&rq->ring_link, &ring->request_list) &&
> +	    i915_request_completed(rq))
>   		i915_request_retire(rq);
>   
>   	/*
> 

Sounds believable.

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

Regards,

Tvrtko
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 5acf869f3ca3..75061f9e48eb 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -694,9 +694,9 @@  i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
 		goto err_unreserve;
 
 	/* Move our oldest request to the slab-cache (if not in use!) */
-	rq = list_first_entry_or_null(&ring->request_list,
-				      typeof(*rq), ring_link);
-	if (rq && i915_request_completed(rq))
+	rq = list_first_entry(&ring->request_list, typeof(*rq), ring_link);
+	if (!list_is_last(&rq->ring_link, &ring->request_list) &&
+	    i915_request_completed(rq))
 		i915_request_retire(rq);
 
 	/*