Re: Apparent strange disk behaviour in 6.0

From: Julian Elischer (julian_at_elischer.org)
Date: 07/31/05

  • Next message: Poul-Henning Kamp: "Re: Apparent strange disk behaviour in 6.0" 
    Date: Sat, 30 Jul 2005 15:31:40 -0700
To: Poul-Henning Kamp <phk@haven.freebsd.dk>

    Poul-Henning Kamp wrote:
    > In message <42EBD958.6040402@elischer.org>, Julian Elischer writes:
    >
    >
    >>>If you know your queue-theory, you also know why busy% is
    >>>a pointless measurement: It represents the amount of time
    >>>where the queue is non-empty. It doesn't say anything about
    >>>how quickly the queue drains or fills.
    >>
    >>exactly.. I'm trying to work out why teh read and write queues are empty for so
    >>much time in a transaction that SHOULD be disk bound....
    >
    >
    > I am very confident that the disk statistics collected in GEOM don't lie:
    > your disks are idle because nobody submits I/O requests.
    >
    > Look at your scheduler...

    I plan on doing just that..

    I didn't say it was a problem in geom.. I just said that
    it is worth investigating why there is no cannel saturation when in theory that
    should be teh bottleneck. I have noticed this before..

    5 & 6 sometimes just don't seem to be "trying". they often have idle time when I
    would expect none.

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