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    SubjectRe: [RFC][PATCH] Runtime switching of the idle function [take 2]
    Steven Rostedt <> wrote:
    > On Mon, 2005-11-28 at 19:02 -0800, Andrew Morton wrote:
    > > Steven Rostedt <> wrote:
    > > >
    > > > This patch creates a directory in /sys/kernel called idle.
    > > >
    > >
    > > At no point do you appear to explain _why_ the kernel needs this feature?
    > Sorry about that. This originally came up when we had problems with the
    > AMD64 x2 in the -rt patch. It was noted that the TSCs would get very
    > far out of sync and cause problems.

    Unsynced TSCs are rare, but they happen. I guess even if we were to resync
    them, these measurements would screw up.

    > 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..

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      Last update: 2005-11-29 05:06    [W:0.021 / U:155.264 seconds]
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