Re: Performance Problems.. Server hardware smoked by $500 box?

From: Mark Terribile (materribile_at_yahoo.com)
Date: 09/11/03

  • Next message: Aditya: "Re: install freebsd on rlx 300ex"
    Date: Thu, 11 Sep 2003 13:07:57 -0700 (PDT)
    To: freebsd-questions@freebsd.org
    
    

    John Straiton writes:

    > I'm pretty confused right now with trying to
    > determine the nature of a performance problem ...
    > on one of my servers. ... in pulling up websites
    > from the machine, my silly POS development
    > box has nearly double performance ...

    There's lots of tricky stuff that can be going wrong.
    I spent some time in my last two jobs (anybody got
    a new one in NJ?) on speeding up stuff like this
    and the first thing I try to do is put some kind of
    steady-state load on the boxen and monitor each box
    involved with systat 1 -vmstat . There's one hell
    of a lot of information there, and interactions are
    sometimes hard to see. If the CPU is fully occupied,
    it could be the network stack (which will NOT show
    up at interrupt level) and that can depend on what
    interface chipset you're using as well. Or it could
    be ... well, get the data first. If you'd like to
    send me a few sample screens, I'll try to make
    suggestions on what to check next. You want to have
    a series from each of the three configurations you're
    using. And being able to _watch_ what's happening
    on systat is worth a whole lot of non-sequenced
    snapshots.

    Are you running firewall software on the production
    machine? I don't know how the FreeBSD version will
    affect performance, but it can't help. How about
    the reports from top ? What do they say? What's
    soaking up the processor?

    Running on a 1GHz PIII two years ago, I was able to
    get a web proxy (not squid!) to serve 1500+ requests
    per second, with about 200 MBit/sec of ethernet
    traffic
    (inbound and out). (The product never made it into
    full-scale production, largely due to financial
    problems in the large, well-known corporation.)
    So the problem isn't horsepower, but something not
    using it well.

    Can you try running the back end box on a simple
    disk without the RAID in the way? I don't recall
    all the properties of RAID 5 right now, but in general
    RAID trades disk transactions away to get disk
    throughput. In your application, you probably need
    transactions more than throughput.

    Dumb question: have you tried swapping cables/ports
    on the ethernet connections? Does one link support
    jumbo frames and the other not? How about network
    buffers: have you got enough configured, and how
    many are tied up at a time?

    Performance is often a negative art: find the worst
    roadblock and remove it, then the next worst after
    that, and so forth.

                                       Mark Terribile

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  • Next message: Aditya: "Re: install freebsd on rlx 300ex"

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