On Sun, Sep 20, 2020 at 10:05:39PM +0300, Oded Gabbay wrote: > On Sun, Sep 20, 2020 at 11:47 AM Greg Kroah-Hartman > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > On Sat, Sep 19, 2020 at 04:22:35PM -0300, Jason Gunthorpe wrote: > > > On Sat, Sep 19, 2020 at 07:27:30PM +0200, Greg Kroah-Hartman wrote: > > > > > It's probably heresy, but why do I need to integrate into the RDMA subsystem ? > > > > > I understand your reasoning about networking (Ethernet) as the driver > > > > > connects to the kernel networking stack (netdev), but with RDMA the > > > > > driver doesn't use or connect to anything in that stack. If I were to > > > > > support IBverbs and declare that I support it, then of course I would > > > > > need to integrate to the RDMA subsystem and add my backend to > > > > > rdma-core. > > > > > > > > IBverbs are horrid and I would not wish them on anyone. Seriously. > > > > > > I'm curious what drives this opinion? Did you have it since you > > > reviewed the initial submission all those years ago? > > > > As I learned more about that interface, yes, I like it less and less :) > > > > But that's the userspace api you all are stuck with, for various > > reasons, my opinion doesn't matter here. > > > > > > I think the general rdma apis are the key here, not the userspace api. > > > > > > Are you proposing that habana should have uAPI in drivers/misc and > > > present a standard rdma-core userspace for it? This is the only > > > userspace programming interface for RoCE HW. I think that would be > > > much more work. > > > > > > If not, what open source userspace are you going to ask them to > > > present to merge the kernel side into misc? > > > > I don't think that they have a userspace api to their rdma feature from > > what I understand, but I could be totally wrong as I do not know their > > hardware at all, so I'll let them answer this question. > > Hi Greg, > We do expose a new IOCTL to enable the user to configure connections > between multiple GAUDI devices. How is it different from RDMA QP configuration? > > Having said that, we restrict this IOCTL to be used only by the same > user who is doing the compute on our device, as opposed to a real RDMA > device where any number of applications can send and receive. The ability to support multiple applications is not RDMA-requirement, but the implementation. For example MPI jobs are single user of RDMA device. > In addition, this IOCTL limits the user to connect ONLY to another > GAUDI device and not to a 3rd party RDMA device. I don't see how it is different from EFA with their SQD QP type or mlx5 devices with DC QPs that you can connect only to similar devices (no interoperability). Thanks
