[Mesa-dev] [Mesa-stable] [PATCH] i965/skl: Use larger URB size where available.

[Emil Velikov]

Hi Ben,

On 11 September 2015 at 20:15, Ben Widawsky <ben at bwidawsk.net> wrote:
> On Fri, Sep 11, 2015 at 12:12:15PM -0700, Jordan Justen wrote:
>> On 2015-09-10 16:59:12, Ben Widawsky wrote:
>> > All SKL SKUs except the lowest one which has half the L3 size actually have 384K
>>
>> These commit message lines seem to wrap a bit long. This first line is
>> 80 characters.
>>
>> > of URB per slice.
>> >
>> > For once, I can explain how this mistake was made and how it was missed in
>> > review...  Historically when we enable a platform and put the production sizes,
>> > you can simply look at the "smallest" SKU and see what its URB size is (and we
>> > assumed it was the 1 slice variant). Since on newer platforms the URB sizes are
>> > scaled automatically by HW, this was sufficient. On SKL, this is a bit different
>> > as the lowest SKU actually has half of the L3 fused off. GT2 is the 1 slice (not
>> > GT1) variant and it has 384K.
>> >
>> > There are no Jenkins tests fixed (or regressions) and we don't expect any fixes
>> > here because you can always run with less URB size - this potentially improves
>> > performance.
>>
>> It would be nice if we were able to find a benchmark that improves
>> from this change. If we can't then maybe we should just remove this
>> paragraph. It seems like the right change regardless.
>>
>> Reviewed-by: Jordan Justen <jordan.l.justen at intel.com>
>
> I think what I'd like to do is run the perf data to make sure there are at least
> no regressions since I am proposing it for stable... Maybe if I don't get around
> to that before the next stable release, we'll bail on it for 10.6
>
Did you get the chance to give this a perf test ? I don't see the
commit landing in master, regardless of the mesa-stable tag.

Thanks
Emil