Re: [PATCH 1/6] NFSD: add the ability to enable use of RWF_DONTCACHE for all IO

Christoph Hellwig
2025-06-12T07:13:34Z

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.