Re: [suse-axp] Good news!

From: Alex Rhomberg (rhomberg@ife.ee.ethz.ch)
Date: Fri Mar 03 2000 - 05:53:08 PST

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    Message-ID: <38BFC3C4.BCB4CB5D@ife.ee.ethz.ch>
Date: Fri, 03 Mar 2000 14:53:08 +0100
From: Alex Rhomberg <rhomberg@ife.ee.ethz.ch>
Subject: Re: [suse-axp] Good news!

    Mattias Hermansson wrote:
    >
    > I compiled lame 3.51 with ccc. The speedincrease was exceptional, more
    > than 3 times the speed of gcc. That's how it's supposed to be. Look here:

    Only three times means that the code was not well optimised ;-)

    Check this out:
    starting point 15 us / Element (on 500 MHz ev56)
    End point after pipeline stalls caused by aliasing problems were
    removed:
    (on 666 MHz ev67)
    g++ -O3
    Timer 1 integrate & scatter: 7.462 us (pitiful 107.2 MFLOPS!)

    ccc -O3
    Timer 1 integrate & scatter: 1.537 us (mindboggling 520.5 MFLOPS!)

    (on 500 MHz ev56)
    g++ -O3
    Timer 1 integrate & scatter: 12.226 us (pitiful 65.4 MFLOPS!)

    ccc -O3
    Timer 1 integrate & scatter: 3.083 us (mindboggling 259.5 MFLOPS!)

    A slight difference of a factor 4 to 5 with well good code. The bad code
    I had before had about a factor of two difference

    - Alex

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