Re: [PATCH v2] drm/i915: Retire before attempting to evict from the active lists

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 09/12/2016 15:05, Chris Wilson wrote:
> Some object retain an extra pin whilst they are active (e.g. contexts).
> This excludes them from being considered for eviction unless we idle the
> GPU. If before we look at the active list, before we retire we can
> hopefully remove a few excess pins and reduce the amount of searching
> required.
>
> v2: Similar principle applies to evict_for_vma
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_gem_evict.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c
> index a3f7f1ca6f21..689338e22ba8 100644
> --- a/drivers/gpu/drm/i915/i915_gem_evict.c
> +++ b/drivers/gpu/drm/i915/i915_gem_evict.c
> @@ -130,7 +130,14 @@ i915_gem_evict_something(struct i915_address_space *vm,
>  				    start, end,
>  				    flags & PIN_HIGH ? DRM_MM_INSERT_HIGH : 0);
>
> -	if (flags & PIN_NONBLOCK)
> +	/* Retire before we search the active list. Although we have
> +	 * reasonable accuracy in our retirement lists, we may have
> +	 * a stray pin (preventing eviction) that can only be resolved by
> +	 * retiring.
> +	 */
> +	if (!(flags & PIN_NONBLOCK))
> +		i915_gem_retire_requests(dev_priv);
> +	else
>  		phases[1] = NULL;
>
>  search_again:
> @@ -236,6 +243,14 @@ int i915_gem_evict_for_vma(struct i915_vma *target, unsigned int flags)
>  	lockdep_assert_held(&target->vm->i915->drm.struct_mutex);
>  	trace_i915_gem_evict_vma(target, flags);
>
> +	/* Retire before we search the active list. Although we have
> +	 * reasonable accuracy in our retirement lists, we may have
> +	 * a stray pin (preventing eviction) that can only be resolved by
> +	 * retiring.
> +	 */
> +	if (!(flags & PIN_NONBLOCK))
> +		i915_gem_retire_requests(target->vm->i915);
> +
>  	check_color = target->vm->mm.color_adjust;
>  	if (check_color) {
>  		/* Expand search to cover neighbouring guard pages (or lack!) */
>

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

Regards,

Tvrtko
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