From: Trond Myklebust <trond.myklebust@fys.uio.no>
Subject: Re: Client performance questions
Date: Thu, 13 Dec 2007 19:57:02 -0500
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To: Orion Poplawski <orion@cora.nwra.com>
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On Thu, 2007-12-13 at 17:07 -0700, Orion Poplawski wrote:
> Trond Myklebust wrote:
> > 
> > Have you tried increasing the value
> > in /proc/sys/fs/nfs/nfs_congestion_kb ?
> 
> Well, I just came across this message while trying to improve NFS 
> performance locally.  On my F8 client, it is set to 30400 by default. 
> Changing to 60800 kills performance.  Writes go from ~20MB/s to ~5MB/s, 
> reads from ~80MB/s to ~47MB/s as measured by bonnie++.
> 
> Expected?

UDP? If so, then possibly yes. UDP has lousy congestion control, so if
the server gets too busy to respond, then performance dies.

Trond