[Intel-gfx] [PATCH 4/6] drm/i915: Free batch pool when idle

[Tvrtko Ursulin]

On 03/09/2015 09:55 AM, Chris Wilson wrote:
> At runtime, this helps ensure that the batch pools are kept trim and
> fast. Then at suspend, this releases memory that we do not need to
> restore. It also ties into the oom-notifier to ensure that we recover as
> much kernel memory as possible during OOM.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_gem.c | 13 ++++++++++++-
>   1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 9f33005bdfd1..efb5545251c7 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2849,8 +2849,19 @@ i915_gem_idle_work_handler(struct work_struct *work)
>   {
>   	struct drm_i915_private *dev_priv =
>   		container_of(work, typeof(*dev_priv), mm.idle_work.work);
> +	struct drm_device *dev = dev_priv->dev;
> +
> +	intel_mark_idle(dev);
>
> -	intel_mark_idle(dev_priv->dev);
> +	if (mutex_trylock(&dev->struct_mutex)) {
> +		struct intel_engine_cs *ring;
> +		int i;
> +
> +		for_each_ring(ring, dev_priv, i)
> +			i915_gem_batch_pool_fini(&ring->batch_pool);

This is sooo bad... destructor in the idle handler, what message does 
that send? :D

> +
> +		mutex_unlock(&dev->struct_mutex);
> +	}

Would it be worth self-re-arming if trylock fails? I couldn't 
immediately figure out if last retirement can somehow race with a 
struct_mutex holder somewhere.

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

Regards,

Tvrtko