Re: Old SUN NFS performance papers.

From: Dominic Mitchell (dom_at_happygiraffe.net)
Date: 01/25/04

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    Date: Sun, 25 Jan 2004 11:04:25 +0000
To: Robert Watson <rwatson@FreeBSD.ORG>

    On Sat, Jan 24, 2004 at 09:14:51PM -0500, Robert Watson wrote:
    > I haven't done much benchmarking on NFS lately, but something worth
    > remembering is that people have spent a lot of time researching and
    > optimizing TCP for a variety of connection types, whereas the NFS code
    > basically has a static implementation of RPC backoff and flow control that
    > hasn't evolved much. TCP is aware of things like the pathwise-mtu to the
    > server and adapts, whereas UDP just loses packets due to fragmentation,
    > especially if you are using larger block sizes. Please do post your
    > discoveries on performance@, and perhaps we could build an NFS performance
    > tuning section in the FreeBSD Handbook (or if there's not that much
    > content, add it to the FAQ)?

    I'm just playing with this... The first thing to note (probably) is to
    check that you can ping your server with a similiar size packet to the
    one you're using. I realised that my network isn't as robust as I
    thought it was very quickly yesterday, when pinging my server with an 8k
    packet. I was seeing 70% packet loss. The default ping showed no
    problems at all.

    The reason I mention it is that I'd been playing with NFS tuning because
    I had been seeing lockups. But the fault really lies at a lower level
    than NFS, it appears.

    -Dom
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