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Thread: A Plethora Of Linux Power Tests Are On The Way

  1. #11
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    Jun 2011
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    Quote Originally Posted by chithanh View Post
    You correctly state that "major kernel power regressions that are hitting many mobile Linux users", however you proceed to measure the power draw on desktop systems. Whether the results can be transfered to mobile setups is questionable and would have to be verified there anyway.

    I think the most meaningful results you get from directly measuring the voltage and current coming from a notebook battery. That way you avoid both the inefficiency in the power supply and the inefficiency in the charging logic, both of which don't really matter to mobile users but still skew the results.
    for the purposes of the power usage benchmarking, I don't see a need for accurate measurements of the laptop sans the power supply.

    power draw will still increase from the wall when using the newer kernels that aren't regulating the system properly.

    for that matter, this has a lot of interest for servers as well as mobile. When you are running 400+ linux servers in a datacenter, you don't want to upgrade to something that will multiply your power usage draw.

    for a laptop it goes up a couple watts, for a datacenter it goes up a kilowatt or more...

  2. #12
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    It is even worse. Imagine the following hypothetical and completely made up situation: The system firmware can perform function X using interrupts or busy-waiting. Using busy-waiting, performance in GPU-bound 3dMark06 is 0.1% higher, but power consumption increases due to CPU load. In order to look better in benchmarks, the manufacturer switches between interrupts while on battery power and busy-waiting while on AC power.
    Now two regressions are independently introduced in the kernel, regression A causes more power consumption for the interrupt case and regression B causes more power consumption in the busy-wait case.

    What mobile users care about is regression A, but testing on AC power only finds regression B.
    Quote Originally Posted by Lederhosen View Post
    When you are running 400+ linux servers in a datacenter, you don't want to upgrade to something that will multiply your power usage draw.

    for a laptop it goes up a couple watts, for a datacenter it goes up a kilowatt or more...
    For datacenters, you need to plan power supply and cooling according to TDP/peak power consumption anyway, so I don't think it will have a dramatic impact.
    Last edited by chithanh; 06-20-2011 at 12:29 PM.

  3. #13
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    May 2011
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    At datacenters, they don't use much laptops. A desktop or server does not have the advanced power management a laptop has, and is affected much less.

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