Re: sendfile+zerocopy: fairly sexy (nothing to do with ECN)

From: Trond Myklebust (
Date: Fri Feb 02 2001 - 07:14:33 EST

>>>>> " " == Andrew Morton <> writes:

> Much the same story. Big increase in sendfile() efficiency,
> small drop in send() and NFS unchanged.

This is normal. The server doesn't do zero copy reads, but instead
copies from the page cache into an NFS-specific buffer using
file.f_op->read(). Alexey and Dave's changes are therefore unlikely to
register on NFS performance (other than on CPU use as has been
mentioned before) until we implement a sendfile-like scheme for knfsd
over TCP.
I've been wanting to start doing that (and also to finish the client
conversion to use the TCP zero-copy), but I'm pretty pressed for time
at the moment.

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