On Tue, Apr 30, 2019 at 08:13:54PM +0300, Yuval Shaia wrote: > On Mon, Apr 22, 2019 at 01:45:27PM -0300, Jason Gunthorpe wrote: > > On Fri, Apr 19, 2019 at 01:16:06PM +0200, Hannes Reinecke wrote: > > > On 4/15/19 12:35 PM, Yuval Shaia wrote: > > > > On Thu, Apr 11, 2019 at 07:02:15PM +0200, Cornelia Huck wrote: > > > > > On Thu, 11 Apr 2019 14:01:54 +0300 > > > > > Yuval Shaia <yuval.shaia@xxxxxxxxxx> wrote: > > > > > > > > > > > Data center backends use more and more RDMA or RoCE devices and more and > > > > > > more software runs in virtualized environment. > > > > > > There is a need for a standard to enable RDMA/RoCE on Virtual Machines. > > > > > > > > > > > > Virtio is the optimal solution since is the de-facto para-virtualizaton > > > > > > technology and also because the Virtio specification > > > > > > allows Hardware Vendors to support Virtio protocol natively in order to > > > > > > achieve bare metal performance. > > > > > > > > > > > > This RFC is an effort to addresses challenges in defining the RDMA/RoCE > > > > > > Virtio Specification and a look forward on possible implementation > > > > > > techniques. > > > > > > > > > > > > Open issues/Todo list: > > > > > > List is huge, this is only start point of the project. > > > > > > Anyway, here is one example of item in the list: > > > > > > - Multi VirtQ: Every QP has two rings and every CQ has one. This means that > > > > > > in order to support for example 32K QPs we will need 64K VirtQ. Not sure > > > > > > that this is reasonable so one option is to have one for all and > > > > > > multiplex the traffic on it. This is not good approach as by design it > > > > > > introducing an optional starvation. Another approach would be multi > > > > > > queues and round-robin (for example) between them. > > > > > > > > > Typically there will be a one-to-one mapping between QPs and CPUs (on the > > > guest). > > > > Er we are really overloading words here.. The typical expectation is > > that a 'RDMA QP' will have thousands and thousands of instances on a > > system. > > > > Most likely I think mapping 1:1 a virtio queue to a 'RDMA QP, CQ, SRQ, > > etc' is a bad idea... > > We have three options, no virtqueue for QP, 1 to 1 or multiplexing. What > would be your vote on that? > I think you are for option #1, right? but in this case there is actually no > use of having a virtio-driver, isn't it? The virtio driver is supposed to be a standard, like a hardware standard, for doing the operation. It doesn't mean that every single element under the driver needs to use the virtio format QP. Jason
