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    SubjectRe: bonus inheritance
    Hi Nick,

    On Tue, Mar 16, 2004 at 04:54:49PM +1100, Nick Piggin wrote:
    > Does it help any actual interactivity problem? Unfortunately
    > practically any you make to the scheduler is bound to make
    > things worse for at least one person, so it is difficult to
    > just test things out.

    Well, the interactivity problems existed with O(1) in 2.4.
    The 50% penalty hurt freshly started processes a lot.

    To fix this, the penalty has been set to 95 (5% penalty)
    in 2.6.
    I believe it's cleaner to draw the bonus towards the average
    and inherit a percentage, and thus I set a inheritance percentage
    of 50 in 2.4.

    It was successful in 2.4. In a measurable way.

    In 2.6, it likely will not make a big difference as with giving
    95% of the bonus, you don't change much ...

    So it's more a question of have the concept in there which is
    clearer. More a theoretical thing. Assuming that with 95% chance
    your child has the same character w.r.t. to interactiveness is
    rather high.

    It will be very hard to measure 80% inheritance to 95% penalty
    as for the most important case (starting a process from a shell),
    the results are almost the same.

    The fact that we are more likely to start new processes towards
    the center in our bonus scale certainly makes it faster for the
    scheduler to put them in the right category, so there should be
    some benefit w.r.t. interactiveness. However, those are not easy
    to measure :-(

    I'll see whether we can get some benchmarks anyway.

    Regards,
    --
    Kurt Garloff <garloff@suse.de> Cologne, DE
    SUSE LINUX AG, Nuernberg, DE SUSE Labs (Head)
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