On 6/12/25 3:13 AM, Christoph Hellwig wrote: > On Wed, Jun 11, 2025 at 04:29:58PM -0400, Jeff Layton wrote: >> I think if we can crack the problem of receiving WRITE payloads into an >> already-aligned buffer, then that becomes much more feasible. I think >> that's a solveable problem. > > It's called RDMA :) > > To place write payloads into page aligned buffer, the NIC needs to split > the various headers from the payload. The data placement part of RDMA > naturally takes care of that. If you want to do it without TCP, you need > hardware that is aware of the protocol headers up to the XDR level. I > know and the days where NFS was a big thing there were NICs that could do > this offload with the right firmware, and I wouldn't be surprised if > that's still the case. > > Agreed: RDMA is the long-standing solution to this problem. For TCP: - For low workload intensity, handling unaligned payloads is adequate. - For moderate intensity workloads, software RXE, or better, software iWARP is the right answer. It's just a matter of making those drivers work efficiently. - For high intensity workloads, hardware RDMA is the right answer. -- Chuck Lever
