Messages in this thread | | | Subject | Re: [PATCH RFC 00/15] Add VFIO mediated device support and IMS support for the idxd driver. | From | Jason Wang <> | Date | Wed, 13 May 2020 10:29:31 +0800 |
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On 2020/5/9 下午8:21, Jason Gunthorpe wrote: > On Fri, May 08, 2020 at 05:09:09PM -0700, Raj, Ashok wrote: >> Hi Jason >> >> On Fri, May 08, 2020 at 08:16:10PM -0300, Jason Gunthorpe wrote: >>> On Fri, May 08, 2020 at 01:47:10PM -0700, Raj, Ashok wrote: >>> >>>> Even when uaccel was under development, one of the options >>>> was to use VFIO as the transport, goal was the same i.e to keep >>>> the user space have one interface. >>> I feel a bit out of the loop here, uaccel isn't in today's kernel is >>> it? I've heard about it for a while, it sounds very similar to RDMA, >>> so I hope they took some of my advice... >> I think since 5.7 maybe? drivers/misc/uacce. I don't think this is like >> RDMA, its just a plain accelerator. There is no connection management, >> memory registration or other things.. IB was my first job at Intel, >> but saying that i would be giving my age away:) > rdma was the first thing to do kernel bypass, all this stuff is like > rdma at some level.. I see this looks like the 'warp driver' stuff > redone > > Wow, lots wrong here. Oh well. > >>> putting emulation code back into them, except in a more dangerous >>> kernel location. This does not seem like a net win to me. >> Its not a whole lot of emulation right? mdev are soft partitioned. There is >> just a single PF, but we can create a separate partition for the guest using >> PASID along with the normal BDF (RID). And exposing a consistent PCI like >> interface to user space you get everything else for free. >> >> Yes, its not SRIOV, but giving that interface to user space via VFIO, we get >> all of that functionality without having to reinvent a different way to do it. >> >> vDPA went the other way, IRC, they went and put a HW implementation of what >> virtio is in hardware. So they sort of fit the model. Here the instance >> looks and feels like real hardware for the setup and control aspect. > VDPA and this are very similar, of course it depends on the exact HW > implementation. > > Jason
Actually this is not a must. Technically we can do ring/descriptor translation in the vDPA driver as what zerocopy AF_XDP did.
Thanks
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