Re: [SLE] For or against ..Hyperthreading.

From: John Andersen (jsa_at_pen.homeip.net)
Date: 08/31/03

  • Next message: John Andersen: "Re: [SLE] For or against ..Hyperthreading." 
    To: suse-linux-e@suse.com
Date: Sun, 31 Aug 2003 00:36:51 -0800

    On Saturday 30 August 2003 12:32, Bruce Marshall wrote:
    > I'll take a single cpu any day over multiple cpu's that DON'T ADD UP TO
    > MORE MIPS than the single cpu. And that was my point.

    A very well reasond answer Bruce.

    Unfortunatly it just proves you have never touched a Dual CPU machine
    running and SMP kernel in your life.

    Because in spite of your reasoning, the facts are the opposite.

    ANYONE who has used dualies would tell you two 500hmz CPUs
    easliy outperform a single 1Ghz cpu on the normal mix
    of applications you run on a typical linux machine, and they do it for
    LESS money. Usually enough less to afford the
    dual motherboard.

    CPU time is hardly ever the bottelneck in computers
    these days, except on the most compute intensive task.

    You assume in your SETI example that the CPU doing
    updatedb does nothing else except the updatedb. That's not
    true, it can run SETI while it is waiting on diskIO.

    Instruction fetch takes longer than instruction execution
    by several orders of magnitude. With two CPUs
    fetching data and instructions tasks are seldom ever
    backed up, and the machine remains responsive
    even under high load.

    A load of 50 would burry most single processor machines
    yet I've seen that often on a busy dual processor machine
    and it just runs right thru it.

    In all but the most compute intensive tasks I'll take
    two half speed CPUs over a single full-speed
    one any day.

    I ran RC5 crunchers in several of my machines for several
    years. The dualies (running two curnchers) always
    outperformed Single CPU machines twice their speed
    even though they theoretically should not have had an
    advantage on such a compute intensive task.

    If you're baseing your theory on Win2k or NT platforms you'd be
    right, Windows can only get 1.4 times a single processor
    performance with dual processors. Linux gets 2x.

    And when you want to do an addtionial task theres always
    a cpu cycle available - never any sluggish preformance.

    Don't theorize. Go get a dualie and bench it. 

    -- 
_____________________________________
John Andersen
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  • Next message: John Andersen: "Re: [SLE] For or against ..Hyperthreading."

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