From: Trond Myklebust <trond.myklebust@fys.uio.no>
Subject: Re: Re: [PATCH] zerocopy NFS for 2.5.43
Date: Wed, 23 Oct 2002 17:23:09 +0200
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Cc: Hirokazu Takahashi <taka@valinux.co.jp>,
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To: Neil Brown <neilb@cse.unsw.edu.au>
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>>>>> " " == Neil Brown <neilb@cse.unsw.edu.au> writes:

     > Hmm. I wonder what plans there are for this w.r.t. to NFSv4
     > client.  Andy? Trond?

There's really no need for anything beyond what we have. There's no
call in the client for stringing more than one set of pages together:
you are always dealing with a single set of contiguous pages to
read/write.

     > I suspect that COMPOUNDS with multiple READ or WRITE requests
     > would be fairly rare, and it would probably be reasonable to
     > respond with ERESOURCE (or however it is spelt).

Alternatively, you could add a list_head to the xdr_buf struct so that
you can string several of them together. Frankly, though, it would be
a rather strange NFSv4 client that wants to do this sort of
operation. There's just no advantage to it...

     > I was thinking it would be nice to be able to do the
     > udp-checksum at the same time as the copy-into-page-cache, but
     > maybe we just say that you need a NIC that does checksums if
     > you want to do single-copy NFS writes.

Right. The very last thing you want to do is to copy into the page
cache, then find out that the checksum didn't match up.

Cheers,
  Trond


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