Random short freezes due to TTM buffer migrations

[Christian König]

Am 16.08.2016 um 17:56 schrieb Marek Olšák:
> On Tue, Aug 16, 2016 at 5:27 PM, Christian König
> <deathsimple at vodafone.de> wrote:
>> Hi Marek,
>>
>> I'm already working on this.
>>
>> My current approach is to use a custom BO manager for VRAM with TTM and so
>> split allocations into chunks of 4MB.
>>
>> Large BOs are still swapped out as one, but it makes it much more likely to
>> that you can allocate 1/2 of VRAM as one buffer.
> Do you mean GTT->swap migrations or VRAM->GTT?

VRAM->GTT. In other words the BO is always either completely in VRAM or 
complete in GTT space, not partially in GTT and partially in VRAM.

>
> In Mesa, I can at least split MSAA color and depth buffers, because:
> - I don't have to support sharing.
> - They are big.
> - I need different BO priorities for FMASK+CMASK, then the first 2
> samples in one buffer, then the next 2 samples in another buffer, etc.
> - I need to allow different locations for each of those.

That sounds like you want to split such allocations up into multiple BOs 
in Mesa anyway.

The only problem is the increased overhead during command submission.

Regards,
Christian.

> Marek