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    SubjectRe: [NFS] Re: [PATCH] zerocopy NFS for 2.5.36
    Date
    On Saturday 19 October 2002 15:34, Hirokazu Takahashi wrote:
    > Hello,
    >
    > > > Congestion avoidance mechanism of NFS clients might cause this
    > > > situation. I think the congestion window size is not enough
    > > > for high end machines. You can make the window be larger as a
    > > > test.
    > >
    > > Is this a concern on the client only? I can run a test with just one
    > > client and see if I can saturate the 100Mbit adapter. If I can, would we
    > > need to make any adjustments then? FYI, at 115 MB/sec total throughput,
    > > that's only 2.875 MB/sec for each of the 40 clients. For the TCP result
    > > of 181 MB/sec, that's 4.525 MB/sec, IMO, both of which are comfortable
    > > throughputs for a 100Mbit client.
    >
    > I think it's a client issue. NFS servers don't care about cogestion of UDP
    > traffic and they will try to response to all NFS requests as fast as they
    > can.
    >
    > You can try to increase the number of clients or the number of mount points
    > for a test. It's easy to mount the same directory of the server on some
    > directries of the client so that each of them can work simultaneously.
    > # mount -t nfs server:/foo /baa1
    > # mount -t nfs server:/foo /baa2
    > # mount -t nfs server:/foo /baa3

    I don't think it is a client congestion issue at this point. I can run the
    test with just one client on UDP and achieve 11.2 MB/sec with just one mount
    point. The client has 100 Mbit Ethernet, so should be the upper limit (or
    really close). In the 40 client read test, I have only achieved 2.875 MB/sec
    per client. That and the fact that there are never more than 2 nfsd threads
    in a run state at one time (for UDP only) leads me to believe there is still
    a scaling problem on the server for UDP. I will continue to run the test and
    poke a prod around. Hopefully something will jump out at me. Thanks for all
    the input!

    Andrew Theurer
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