Re: [RFC/POC PATCH 01/12] drm/amdgpu: add SVM UAPI definitions

Christian König
2026-04-21T06:20:09Z

On 4/21/26 07:08, Matthew Brost wrote:
> On Mon, Apr 20, 2026 at 08:07:38PM +0200, Christian König wrote:
>> On 4/20/26 18:06, Matthew Brost wrote:
>>> On Mon, Apr 20, 2026 at 05:37:43PM +0200, Christian König wrote:
>>>> On 4/20/26 15:30, Huang, Honglei1 wrote:
>>>>> On 4/20/2026 8:15 PM, Christian König wrote:
...
>> Either you set the information per-device and then each device only gets the information if it needs to migrate the page to it's own local memory or you have global information.
>>
>> So why does a device fd needs to know about remote pgmap?
>>
>
> Simplest example:
>
> Devices A and B. The user sets the preferred placement to Device A.
> Device B faults first, and Device B moves memory to Device A via remote
> pull and can access locally via P2P, scale-up, etc. Avoid a double
> bounce once Device A faults.

So you basically tell the device as soon as you want to access this VA please push the underlying memory away to a different device?

I didn't thought that would be a valid use case. As far as I can see the only thing you avoid is updating your page tables on the faulting device twice.

Thanks for the explanation, that was absolutely not obvious. Going to discuss that with the team on the next meeting.

Christian.

>
> Matt