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Thread: The Impact Of A Tickless Kernel

  1. #1
    Join Date
    Jan 2007

    Default The Impact Of A Tickless Kernel

    Phoronix: The Impact Of A Tickless Kernel

    In this article we will be looking at the impact of CONFIG_NO_HZ/Dynamic Ticks, which will be found in the Linux 2.6.21 kernel. The option has been available as a patch for quite a while, but not until Linux 2.6.21-rc1 had it been merged into the upstream kernel. When enabled, there will only be timer ticks when they are needed. The end-user benefit is cooler-running processors and increased power savings. We have investigated this change with a notebook and desktop computer.

  2. #2
    Join Date
    Jun 2008


    Those savings weren't as large as anecdotal evidence around the net would suggest.

    There shouldn't be much difference under full load, as the system will be awake all the time in any case. With no load at all, the system is doing very little in any case, and any power savings in the CPU might be hidden below the noise floor. I would assume the largest impact is with sporadic activity, but I offer no clues as to how one might measure that reliably.

  3. #3
    Join Date
    Apr 2008


    Erm, CONFIG_NO_HZ is available for x86_64 kernels since 2.6.25 or 2.6.24 (can't remember which). I know because I'm running a x86_64 kernel with that option enabled.
    Edit: just noticed the date on that post
    Last edited by apaige; 06-10-2008 at 12:05 PM.

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