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    SubjectRe: [Linux-ia64] Re: web page on O(1) scheduler
    At 10:05 AM 6/2/2003 +0200, Ingo Molnar wrote:

    >On Thu, 29 May 2003, Mike Galbraith wrote:
    >
    > > [...] What makes more sense to me than the current implementation is to
    > > rotate the entire peer queue when a thread expires... ie pull in the
    > > head of the expired queue into the tail of the active queue at the same
    > > time so you always have a player if one exists. (you'd have to select
    > > queues based on used cpu time to make that work right though)
    >
    >we have tried all sorts of more complex yield() schemes before - they
    >sucked for one or another workload. So in 2.5 i took the following path:
    >make yield() _simple_ and effective, ie. expire the yielding task (push it
    >down the runqueue roughly halfway, statistically) and dont try to be too
    >smart doing it. All the real yield() users (mostly in the kernel) want it
    >to be an efficient way to avoid livelocks. The old 2.4 yield
    >implementation had the problem of enabling a ping-pong between two
    >higher-prio yielding processes, until they use up their full timeslice.

    (yeah, i looked at that in ktracer logs. cpu hot-potato sucks;)

    >(we could do one more thing that still keeps the thing simple: we could
    >re-set the yielding task's timeslice instead of the current 'keep the
    >previous timeslice' logic.)

    (more consistent)

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