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    Subject2.2.10-ac4 / knfsd 1.4.1 poor parallel reading performance

    Hello,

    I am running 2.2.10-ac4 + knfsd 1.4.1, and, as for the previous
    versions, the server behaves strangely very badly when concurrent
    readers are accessing the NFS exported partitions.

    Using iozone, I can achieve roughly 6 Mo/s with one reader.
    Using many readers (from 2 readers upwards), reading rate
    drops to 1,5 Mo/s cumulated. For example, with 3 readers, each
    of them reads at 500 Ko/s, and the load of the server climbs to
    7+.

    Using many iozones locally on the server shows that the cumulated
    reading rate is independant (or just with little performance loss)
    to the rate obtained with one reader (ie, ~ 10 Mo/s).

    So, the problem seems to be the simultaneous NFS accesses (maybe combined
    with simultaneous disk accesses).

    Any idea ?

    A+,
    --
    Thierry Danis
    Poste : 53 53 danis@spmo.sagem.fr

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