Re: [PATCH v4 04/14] PCI/P2PDMA: Clear ACS P2P flags for all devices behind switches

From: Logan Gunthorpe
Date: Thu May 10 2018 - 15:00:22 EST

On 10/05/18 12:41 PM, Stephen Bates wrote:
> Hi Jerome
>> Note on GPU we do would not rely on ATS for peer to peer. Some part
>> of the GPU (DMA engines) do not necessarily support ATS. Yet those
>> are the part likely to be use in peer to peer.
> OK this is good to know. I agree the DMA engine is probably one of the GPU components most applicable to p2pdma.
>> We (ake GPU people aka the good guys ;)) do no want to do peer to peer
>> for performance reasons ie we do not care having our transaction going
>> to the root complex and back down the destination. At least in use case
>> i am working on this is fine.
> If the GPU people are the good guys does that make the NVMe people the bad guys ;-). If so, what are the RDMA people??? Again good to know.

The NVMe people are the Nice Neighbors, the RDMA people are the
Righteous Romantics and the PCI people are the Pleasant Protagonists...