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Date: Wed, 10 Oct 2012 08:08:44 -0400 (EDT)
From: Rick Macklem <rmacklem@uoguelph.ca>
To: Garrett Wollman <wollman@bimajority.org>
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Subject: Re: NFS server bottlenecks
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Cc: Nikolay Denev <ndenev@gmail.com>, freebsd-hackers@freebsd.org
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Garrett Wollman wrote:
> <<On Tue, 9 Oct 2012 20:18:00 -0400 (EDT), Rick Macklem
> <rmacklem@uoguelph.ca> said:
> 
> > And, although this experiment seems useful for testing patches that
> > try
> > and reduce DRC CPU overheads, most "real" NFS servers will be doing
> > disk
> > I/O.
> 
> We don't always have control over what the user does. I think the
> worst-case for my users involves a third-party program (that they're
> not willing to modify) that does line-buffered writes in append mode.
> This uses nearly all of the CPU on per-RPC overhead (each write is
> three RPCs: GETATTR, WRITE, COMMIT).
> 
Yes. My comment was simply meant to imply that his testing isn't a
realistic load for most NFS servers. It was not meant to imply that
reducing the CPU overhead/lock contention of the DRC is a useless
exercise.

rick

> -GAWollman