On 2018-02-14 02:01 PM, Felix Kuehling wrote: > On 2018-02-14 01:33 PM, Christian König wrote: >> Am 14.02.2018 um 19:24 schrieb Felix Kuehling: >>> On 2018-02-14 01:15 PM, Christian König wrote: >>> >>>> As I said that concept is incompatible with the requirements on A+A >>>> systems, so we need to find another solution to provide the >>>> functionality. >>> Do you mean you need to find another solution for A+A buffer sharing >>> specifically? Or is this a more general statement that includes the >>> mapping of BOs to multiple VMs on different devices? >> A more general statement. We need to find a solution which works for >> everybody and not just works like this in the KFD but breaks A+A >> buffer sharing and so needs to be disabled there. > Well, KFD sharing system memory BOs between GPUs doesn't break A+A. > Implementing a solution for A+A that involves DMABufs will not affect > KFD. And KFD isn't actually broken as far as I know. Once you have a > solution for A+A, maybe it will help me understand the problem and I can > evaluate whether the solution is applicable to KFD and worth adopting. > But for now I have neither a good understanding of the problem, no > evidence that there is a problem affecting KFD, and no way towards a > solution. Let me add, I'm definitely interested in your solution for P2P, because we want to enable that for KFD for large-BAR systems. For now I'm not upstreaming any P2P support, because I know that our current hack is going to be superseded by the solution you're working on. Thanks,  Felix > >>>> What's on my TODO list anyway is to extend DMA-buf to not require >>>> pinning and to be able to deal with P2P. >>> Sounds good. That said, KFD is not using DMABufs here. >>> >>>> The former is actually rather easy and already mostly done by sharing >>>> the reservation object between exporter and importer. >>>> >>>> The later is a bit more tricky because I need to create the necessary >>>> P2P infrastructure, but even that is doable in the mid term. >>> The sooner you can share your plans, the better. Right now I'm in a bit >>> of limbo. I feel you're blocking KFD upstreaming based on AMDGPU plans >>> and changes that no one has seen yet. >> Well as far as I understand it that is not blocking for the current >> upstreaming because you didn't planned to upstream this use case >> anyway, didn't you? > Which use case? The current patch series enables multi-GPU buffer > sharing of system memory BOs. If it is actually broken, I can reduce the > scope to single-GPU support. But I have no evidence that multi-GPU is > actually broken. > > Regards, >  Felix > >> Regards, >> Christian. >> >>> Thanks, >>>   Felix >>> >>>> Regards, >>>> Christian.
