[Intel-gfx] [PATCH v3 4/7] drm/i915: Cache LRC state page in the context

[Tvrtko Ursulin]

On 12/01/16 12:12, Chris Wilson wrote:
> On Tue, Jan 12, 2016 at 11:56:11AM +0000, Tvrtko Ursulin wrote:
>> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>
>> LRC lifetime is well defined so we can cache the page pointing
>> to the object backing store in the context in order to avoid
>> walking over the object SG page list from the interrupt context
>> without the big lock held.
>>
>> v2: Also cache the mapping. (Chris Wilson)
>> v3: Unmap on the error path.
>
> Then we only use the lrc_state_page in the unmapping, hardly worth the
> cost of saving it.

Ok.

Do you also know if this would now require any flushing or something if 
previously kunmap_atomic might have done something under the covers?

> The reg_state is better associated with the ring (since it basically
> contains the analog of the RING_HEAD and friends).

Hm, not sure. The page belongs to the object from that anonymous struct 
in intel_context so I think it is best to keep them together.

Regards,

Tvrtko