Re: [PATCH] drm/i915: Remove the duplicated logic between the two shrink phases

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Oct 03, 2014 at 10:29:51AM +0100, Chris Wilson wrote:
> We can use the same logic to walk the different bound/unbound lists
> during shrinker (as the unbound list is a degenerate case of the bound
> list), slightly compacting the code.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

Queued for -next, thanks for the patch.
-Daniel
> ---
>  drivers/gpu/drm/i915/i915_gem.c | 49 ++++++++++++++++-------------------------
>  1 file changed, 19 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index fccb811ba6da..f6893bc8613c 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2040,7 +2040,14 @@ unsigned long
>  i915_gem_shrink(struct drm_i915_private *dev_priv,
>  		long target, unsigned flags)
>  {
> -	const bool purgeable_only = flags & I915_SHRINK_PURGEABLE;
> +	const struct {
> +		struct list_head *list;
> +		unsigned int bit;
> +	} phases[] = {
> +		{ &dev_priv->mm.unbound_list, I915_SHRINK_UNBOUND },
> +		{ &dev_priv->mm.bound_list, I915_SHRINK_BOUND },
> +		{ NULL, 0 },
> +	}, *phase;
>  	unsigned long count = 0;
>  
>  	/*
> @@ -2062,48 +2069,30 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
>  	 * dev->struct_mutex and so we won't ever be able to observe an
>  	 * object on the bound_list with a reference count equals 0.
>  	 */
> -	if (flags & I915_SHRINK_UNBOUND) {
> +	for (phase = phases; phase->list; phase++) {
>  		struct list_head still_in_list;
>  
> -		INIT_LIST_HEAD(&still_in_list);
> -		while (count < target && !list_empty(&dev_priv->mm.unbound_list)) {
> -			struct drm_i915_gem_object *obj;
> -
> -			obj = list_first_entry(&dev_priv->mm.unbound_list,
> -					       typeof(*obj), global_list);
> -			list_move_tail(&obj->global_list, &still_in_list);
> -
> -			if (!i915_gem_object_is_purgeable(obj) && purgeable_only)
> -				continue;
> -
> -			drm_gem_object_reference(&obj->base);
> -
> -			if (i915_gem_object_put_pages(obj) == 0)
> -				count += obj->base.size >> PAGE_SHIFT;
> -
> -			drm_gem_object_unreference(&obj->base);
> -		}
> -		list_splice(&still_in_list, &dev_priv->mm.unbound_list);
> -	}
> -
> -	if (flags & I915_SHRINK_BOUND) {
> -		struct list_head still_in_list;
> +		if ((flags & phase->bit) == 0)
> +			continue;
>  
>  		INIT_LIST_HEAD(&still_in_list);
> -		while (count < target && !list_empty(&dev_priv->mm.bound_list)) {
> +		while (count < target && !list_empty(phase->list)) {
>  			struct drm_i915_gem_object *obj;
>  			struct i915_vma *vma, *v;
>  
> -			obj = list_first_entry(&dev_priv->mm.bound_list,
> +			obj = list_first_entry(phase->list,
>  					       typeof(*obj), global_list);
>  			list_move_tail(&obj->global_list, &still_in_list);
>  
> -			if (!i915_gem_object_is_purgeable(obj) && purgeable_only)
> +			if (flags & I915_SHRINK_PURGEABLE &&
> +			    !i915_gem_object_is_purgeable(obj))
>  				continue;
>  
>  			drm_gem_object_reference(&obj->base);
>  
> -			list_for_each_entry_safe(vma, v, &obj->vma_list, vma_link)
> +			/* For the unbound phase, this should be a no-op! */
> +			list_for_each_entry_safe(vma, v,
> +						 &obj->vma_list, vma_link)
>  				if (i915_vma_unbind(vma))
>  					break;
>  
> @@ -2112,7 +2101,7 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
>  
>  			drm_gem_object_unreference(&obj->base);
>  		}
> -		list_splice(&still_in_list, &dev_priv->mm.bound_list);
> +		list_splice(&still_in_list, phase->list);
>  	}
>  
>  	return count;
> -- 
> 2.1.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch