On Wed, Jan 31, 2018 at 02:27:01PM +0200, Marcel Apfelbaum wrote: > It is good to know, but still, passing so much information to kernel > when we can rather "compress" it, maybe it worth a second thought. Not sure. Have to see the whole thing.. > > Well, actually, only a 3rd :| The new MR would likely be 0 based, but > > the VM guest doesn't know about this. So you'd need an API that can do > > arbitrary based to really solve your probably. I guess all HW should > > be able to do this so maybe it is OK? > > The way we solve "the other" half is by intercepting the post-send > requests in hypervisor. At hypervisor level we don't have contiguous virtual > addresses anymore, but we don't need them for 0 based MRs: > The guest still register regular MRs, while the hypervisor will > register a 0 based MR save the guest virtual address of the MR. > At post-send we simply substract the saved MR base address from the work request > buffers and we are back to 0 based MR. That only works for lkeys, the rkey expoeses the base address to the remote - the HV can't fix it.. > Do you have a model in mind? We would really want to try it out. > > By the way, I tried to search in the kernel for vendors implementing > it and I saw maybe one vendor... so maybe 0 based MR is a nice idea > but nothing more. Try the mlx drivers, I think at least one of them can do it today. Jason -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
