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  1. #61
    Joined
    Mar 2004
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    318

    Re: Benchmarks for linux?

    I was wondering does anyone adjust there linux flavor powersafe setting since I just saw someone post on most time the cpu is running not at full speed.I just did the check and i'm running at half speed on my sys and i sure don't know how to change that.So wouldn't that be part of not the big gain.
    . GA-EP45 DS3L 2GIG CORSAIR HITACHI 320 EVGA 260 216 896.

  2. #62
    Joined
    Jul 2001
    Location
    UK
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    51
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    20,229

    Re: Benchmarks for linux?

    Quote Originally Posted by elvin View Post
    I was wondering does anyone adjust there linux flavor powersafe setting since I just saw someone post on most time the cpu is running not at full speed.I just did the check and i'm running at half speed on my sys and i sure don't know how to change that.So wouldn't that be part of not the big gain.
    On my distro, there's a service called cpuspeed that controls throttling. Because I do distributed computing projects I normally just disable that and run flat out full time.

    Most of these throttling technologies should be intelligent so they throttle back when the cpu is idling and kick back up to full power when needed.

  3. #63
    Joined
    Mar 2004
    Posts
    318

    Re: Benchmarks for linux?

    Thx ned I did look into it,but for some reason it wasn't changing for me.I ran wine with game and ran glxgears for a while it was just same speed half not full at anytime.I went ahead and uninstall it to see.

    Ned if you can read post I did on mint 4.0 I found something in wine forum that you may want to do a link and sticky it for the gamers on linux here.
    . GA-EP45 DS3L 2GIG CORSAIR HITACHI 320 EVGA 260 216 896.

  4. #64
    Joined
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    UK
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    Re: Benchmarks for linux?

    Quote Originally Posted by Ned Slider View Post
    It would probably be more realistic to run without any optimizations, otherwise all we're really doing is benchmarking how good a job the compiler does in optimizing the code rather than benchmarking how well the system actually performs at running that code.

    Optimizing benchmark code is an interesting topic I've been looking at recently with the seti project. It goes something like this:

    1. Start benchmark
    2. Perform some time consuming work
    3. Output benchmark result

    Now, if (2) is related to (3), ie the result of the time consuming work is required for the output then everything is fine. But if (2) and (3) are unrelated, for example, with our pi code above where pi is calculated and the final output is simply the time taken, then the optimizer could look at the code and say step (2), the time consuming work, has no relevance to the final result and therefore isn't needed so can be optimized out thus making the program run a lot faster. Of course what save the pi example from this type of over-optimization is that it outputs the results of the pi calculations to the console during step (2).

    We recently had a similar situation with Whetstone and Dhrystone benchmarks used by seti whereby the Windows version of the compiler used was over optimizing the code relative to the linux compiler so the same code would achieve benchmark scores twice as high on windows relative to linux on the same hardware. When the source code was changed to stop this from happening, both platforms achieved similar results despite being optimized and compiled on very different platforms.

    Hope that makes sense!

    Ned
    Quote Originally Posted by Spankin Partier View Post
    So you mean the Windows version was actually droping some of the code by over optimizing it? At least they didn't super optimize it to this:
    Code:
    main()
    {
    }


    And I always thought that compiler optimizations basically just took advantage of additional features that a paticular computer or class of computer had and also made assumptions on which 'work-arounds' were not needed (ie the original Pentium floating point fault). I never knew they could actually affect the work that was being preformed.

    Hmmm. Interesting.
    Old thread, I know, but here's a classic example of what can happen when a compiler over optimizes code:

    http://isc.sans.org/diary.html?storyid=6820

    leading to a security vulnerability in the current Linux kernel.

  5. #65
    Joined
    Oct 2001
    Location
    Southern Ontario
    Age
    45
    Posts
    13,194

    Re: Benchmarks for linux?

    Who needs security checks anyways.

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