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
