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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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