[Intel-gfx] [PATCH 6/6] drm/i915: Store the vma in an rbtree under the object

[Tvrtko Ursulin]

On 01/11/2016 08:50, Chris Wilson wrote:
> On Tue, Nov 01, 2016 at 08:41:01AM +0000, Tvrtko Ursulin wrote:
>>
>> On 31/10/2016 10:26, Chris Wilson wrote:
>>> With full-ppgtt one of the main bottlenecks is the lookup of the VMA
>>> underneath the object. For execbuf there is merit in having a very fast
>>> direct lookup of ctx:handle to the vma using a hashtree, but that still
>>> leaves a large number of other lookups. One way to speed up the lookup
>>> would be to use a rhashtable, but that requires extra allocations and
>>> may exhibit poor worse case behaviour. An alternative is to use an
>>> embedded rbtree, i.e. no extra allocations and deterministic behaviour,
>>> but at the slight cost of O(lgN) lookups (instead of O(1) for
>>> rhashtable). The major of such tree will be very shallow and so not much
>>> slower, and still scales much, much better than the current unsorted
>>> list.
>>>
>>> References: https://bugs.freedesktop.org/show_bug.cgi?id=87726
>>> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>>
>> I suggest leaving this out of the mini-series which fixes the
>> recently introduced bugs.
>
> Just review it now, it's a two year old bug that was impacting the test
> cases I was running... :-p Then we won't have to review it next week ;)

I'll review it, just split it out please so the CI fire can be 
extinguished first.

Regards,

Tvrtko