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    SubjectRe: [PATCH] Make highly niced processes run only when idle
    On Sun, 2001-12-09 at 17:31, Anthony DeRobertis wrote:

    > One of two things:
    > 1) The higher priority task will no longer be runnable; or
    > 2) We gave enough rope to hang yourself, and, well, you did.

    and (3) the lower priority task won't be runnable either.

    Without addressing this (and it is addressable, see below) this feature
    won't make it into the kernel. It isn't an argument to say "we gave you
    the rope and you took it" because if I idle task some random application
    because it deserves little time, I shouldn't have to think of what
    resource/kernel semantics it and another task are going to get into a
    priority inversion fight over.

    I've seen a few solutions. The easiest is to just give idle tasks a
    "boost" on occasion to give them a chance to prevent the deadlock. You
    then, however, have the problem where the tasks can take advantage of
    the boost... Or, we could fix in-kernel deadlocks by doing priority
    inheriting on locks held by A and wanted by B (i.e., if A holds
    something B wants, boost A's priority temporarily to that of B's). But
    that is probably overkill ... note to do any of these it is probably
    cleanest to make a SCHED_IDLE scheduling class.

    maybe I'll put a patch together ...

    Robert Love

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