Re: [NFS] Re: [PATCH] zerocopy NFS for 2.5.36

From: Andrew Theurer (
Date: Tue Oct 22 2002 - 16:16:23 EST

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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This archive was generated by hypermail 2b29 : Wed Oct 23 2002 - 22:01:00 EST