Am 2020-04-20 um 1:44 p.m. schrieb Jacob Pan:
>> The bottom line is, when you allocate a PASID for a context, you want
>> to know how small it needs to be for all the devices that want to use
>> it. If you make it too big, some device will not be able to use it.
>> If you make it too small, you waste precious PASIDs that could be
>> used for other contexts that need them.
>>
> So for AMD, system-wide PASID allocation works with the
> restriction/optimization above?
>
Yes for KFD. On multi-GPU systems we allocate one PASID for the whole
process and use it on all GPUs.

For AMDGPU graphics contexts, we allocate one PASID for each per-GPU
context. But they're allocated from a single global PASID namespace
managed by the AMDGPU driver and shared with KFD. So we're wasting
PASIDs here, but we are compatible with a single system-wide PASID
namespace.

Regards,
  Felix