[PATCH 1/2] drm/amdgpu: Enable scatter gather display support

Marek Olšák maraeo at gmail.com
Wed Mar 21 13:57:31 UTC 2018


On Wed, Mar 21, 2018 at 4:13 AM, Christian König <
ckoenig.leichtzumerken at gmail.com> wrote:

> Am 21.03.2018 um 06:08 schrieb Marek Olšák:
>
> On Tue, Mar 20, 2018 at 4:16 PM, Christian König <christian.koenig at amd.com
> > wrote:
>
>> That's what I meant with use up the otherwise unused VRAM. I don't see
>> any disadvantage of always setting GTT as second domain on APUs.
>>
>> My assumption was that we dropped this in userspace for displayable
>> surfaces, but Marek proved that wrong.
>>
>> So what we should do is actually to add GTT as fallback to all BOs on
>> APUs in Mesa and only make sure that the kernel is capable of handling GTT
>> with optimal performance (e.g. have user huge pages etc..).
>>
>
> VRAM|GTT is practically as good as GTT. VRAM with BO priorities and
> eviction throttling is the true "VRAM|GTT".
>
> I don't know how else to make use of VRAM intelligently.
>
>
> Well why not set VRAM|GTT as default on APUs? That should still save quite
> a bunch of moves even with throttling.
>

I explained why: VRAM|GTT is practically as good as GTT.


>
> I mean there really shouldn't be any advantage to use VRAM any more except
> that we want to use it up as long as it is available.
>

Why are you suggesting to use VRAM|GTT then? Let's just only use GTT on all
APUs.

Marek
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