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    SubjectRe: [PATCH] O13int for interactivity
    Date
    On Tue, 5 Aug 2003 12:21, Nick Piggin wrote:
    > >I've already posted a better solution in O13.1
    >
    > No, this still special-cases the uninterruptible sleep. Why is this
    > needed? What is being worked around? There is probably a way to
    > attack the cause of the problem.

    Sure I'm open to any and all ideas. Cpu hogs occasionally do significant I/O.
    Up until that time they have been only losing sleep_avg as they have spent no
    time sleeping; and this is what gives them a lower dynamic priority. During
    uninterruptible sleep all of a sudden they are seen as sleeping even though
    they are cpu hogs waiting on I/O. Witness the old standard, a kernel compile.
    The very first time you launch a make -j something, the higher the something,
    the longer all the jobs wait on I/O, the better the dynamic priority they
    get, which they shouldn't.

    No, this is not just a "fix the scheduler so you don't feel -j kernel
    compiles" as it happens with any cpu hog starving other tasks, and the longer
    the cpu hogs wait on I/O the worse it is. This change causes a _massive_
    improvement for that test case which usually brings the machine to a
    standstill the size of which is dependent on the number of cpu hogs and the
    size of their I/O wait. I don't think the latest incarnation should be a
    problem. In my limited testing I've not found any difference in throughput
    but I don't have a major testbed at my disposal, nor time to use one if it
    was offered which is why I requested more testing.

    Thoughts?

    Con

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