Re: [PATCH 08/64] drm/i915: Retire oldest completed request before allocating next

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> In order to keep the memory allocated for requests reasonably tight, try
> to reuse the oldest request (so long as it is completed and has no
> external references) for the next allocation.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_gem_request.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
> index 9e9aa6b725f7..ee1189c35509 100644
> --- a/drivers/gpu/drm/i915/i915_gem_request.c
> +++ b/drivers/gpu/drm/i915/i915_gem_request.c
> @@ -226,6 +226,13 @@ __i915_gem_request_alloc(struct intel_engine_cs *engine,
>  	if (ret)
>  		return ret;
>  
> +	if (!list_empty(&engine->request_list)) {
> +		req = list_first_entry(&engine->request_list,
> +				       typeof(*req), list);
> +		if (i915_gem_request_completed(req))
> +			i915_gem_request_retire(req);
> +	}
> +

With the last_submitted_seqno and req->seqno you could get rough
estimation of requests-in-flight and perhaps retire handful more
if the diff is very big?

But one-for-one makes sense.

Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>

>  	req = kmem_cache_zalloc(dev_priv->requests, GFP_KERNEL);
>  	if (!req)
>  		return -ENOMEM;
> -- 
> 2.8.1
>
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