PRT support for amdgpu

[Alex Deucher]

On Mon, Jan 30, 2017 at 7:57 AM, Christian König
<deathsimple at vodafone.de> wrote:
> Hi Dave and Bas,
>
> Hi Dave and Bas,
>
> the following set of patches is a proposal for adding support for partial resident textures (PRT) to the amdgpu kernel module.
>
> The basic idea behind PRT support is that you turn of VM fault reporting and only map parts of a texture into your virtual address space.
>
> When a shader now tries to sample from a not present page it gets a notification instead of a VM fault and can react gracefully by switch to a different LOD for example.

Do we actually need to disable faults?  I guess the shader hw probably
requires it to get the proper result in the shader?

Alex

>
> On our current available hardware generation you can unfortunately only turn of VM faults globally, but on future generation you can do this on a per page basis. So my proposal is to have a consistent interface over all generations with a per mapping PRT flag, but enable/disable it globally on current hardware when the first/last mapping is made/destroyed.
>
> An open problem with the proposal is that we don't know when or if we want to add the userspace implementation into radeonsi.
>
> So price question could you guys use this for radv as well? Or is it sufficient to just write an unit test for it?
>
> Best regards,
> Christian.
>
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