[Intel-gfx] [PATCH 46/64] drm/i915: Count how many VMA are bound for an object

[Tvrtko Ursulin]

On 12/07/16 15:38, Chris Wilson wrote:
> On Tue, Jul 12, 2016 at 03:30:25PM +0100, Tvrtko Ursulin wrote:
>> On 07/07/16 09:41, Chris Wilson wrote:
>>> @@ -3684,6 +3684,9 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
>>>   					    old_read_domains,
>>>   					    old_write_domain);
>>>
>>> +	/* Increment the pages_pin_count to guard against the shrinker */
>>> +	obj->pages_pin_count++;
>>
>> Would it be clearer to look at obj->pin_display in the shrinker?
>> Although it looks like special casing out of the cleanliness of the
>> design in both case so I am not sure.
>
> Yeah. I liked the mechanism of telling the shrinker to avoid certain
> pages by only having to control the pages_pin_count. It feels easier to
> explain to others "the shrinker may reap any object that hasn't pinned
> its pages" (explicitly called i915_gem_object_pin_pages for its own use)
> rather than that + plus a list of exceptions known by the shrinker.

Hm but wait a minute, framebuffer already has the VMA pinned. So how 
will the shrinker reap it?

Regards,

Tvrtko