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    SubjectRe: [patch] idle_task was wasting a lot of CPU
    On Fri, 27 Nov 1998, Linus Torvalds wrote:
    > On Fri, 27 Nov 1998, Andrea Arcangeli wrote:
    > >
    > > The first pending patch is a fix for a bug I discovered last week. The
    > > patch avoid the idle task to continue to run if an useful process is being
    > > wakenup. It make a _big_ difference. Compiling the kernel a `xload' show
    > > that the CPU is used at 100% all the time (5/10% kernel and the other is
    > > gcc). Without this patch xload is far from doing a straight line in the
    > > high part of the graph.
    >
    > Hmm.. The idle tasks _should_ have a negative counter value all the time,
    > at least they used to. That's the proper fix, to make sure that the
    > counter value is never positive in the first place.
    >
    > I wonder when that broke?

    I thought about that too. It process.c we used to mark
    the counter of each idle task to -100 and it had gone
    without a reason.

    Putting it back there won't really work since, on each
    timer interrupt, counter will be reset to 0. IMHO the
    real fix is to mark the idle task with SCHED_YIELD.
    This will work because we never mangle the idle task
    with goodness()... (we don't, do we?)

    regards,

    Rik -- now completely used to dvorak kbd layout...
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