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    SubjectRe: [RFC][PATCH] Runtime switching of the idle function [take 2]

    * Andrew Morton <> wrote:

    > > The way to solve this was to set
    > > idle=poll. The original patch I sent was to allow the user to change to
    > > idle=poll dynamically. This way they could switch to the poll_idle and
    > > run there tests (requiring tsc not to drift) and then switch back to the
    > > default idle to save on electricity.
    > Use gettimeofday()?
    > If it's just for some sort of instrumentation, run NR_CPUS instances
    > of a niced-down busyloop, pin each one to a different CPU? That way
    > the idle function doesn't get called at all..

    idle=poll is also frequently done for performance reasons [it reduces
    idle wakeup latency by 10 usecs] - while it could be turned off if the
    system has been idle for some time. E.g. cpufreqd could sample idle time
    and turn on/off idle=poll. High-performance setups could enable it all
    the time.

    as long as it can be done with zero-cost, i dont see why Steven's patch
    wouldnt be a plus for us. It's a performance thing, and having runtime
    switches for seemless performance features cannot be bad.

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      Last update: 2005-11-29 07:47    [W:0.020 / U:11.280 seconds]
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