Re: I've ran out of ideas

From: Aaron Glenn (aaron.glenn_at_gmail.com)
Date: 11/19/04

  • Next message: Aaron Glenn: "Re: I've ran out of ideas" 
    Date: Thu, 18 Nov 2004 17:53:04 -0800
To: "lukem.freebsd@cse.unsw.edu.au" <lukem.freebsd@cse.unsw.edu.au>

    On Fri, 19 Nov 2004 10:11:59 +1100 (EST),
    lukem.freebsd@cse.unsw.edu.au <lukem.freebsd@cse.unsw.edu.au> wrote:
    > The simple answer is that both iostat and dd are giving you the correct
    > results. Try your dd again with a smaller block size (like the 512 byte
    > default) and you should see that disk throughput is closer to what you are
    > seeing for your web server.

    The /www partition it's reading from was made with -b 65536 and -f 8192.

    > I would theorise that your web server is probably only issuing fairly
    > small disk reads, so your network performance is being bound by the disk.

    That was my first hunch; hence creating a separate partition with
    obscene blocksizes (-:

    > To test this theory, you could:
    >
    > * create an mfs partition and serve off it to see what kind of performance
    > you can get
    > * see if you can tweak the web server to use larger reads and writes.
    >
    > In your original message you said that increasing the disk block size
    > improved performance, which would also indicate that you are being limited
    > by disk performance.

    I doubt increasing it even more would help. Law of diminishing returns
    and all that; then again I'm no expert. Thoughts?

    Regards,
    aaron.glenn
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