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    SubjectRe: [2.4.17/18pre] VM and swap - it's really unusable
    I forgot the line that says: "Oliver pointed out the immediate problem but .."

    On Mon, Jan 14, 2002 at 06:45:48AM -0700, wrote:
    > On Mon, Jan 14, 2002 at 02:17:46PM +0200, Momchil Velikov wrote:
    > > >>>>> "yodaiken" == yodaiken <> writes:
    > > yodaiken> It's not even clear how preempt is supposed to interact with SCHED_FIFO.
    > >
    > > How so ? The POSIX specification is not clear enough or it is not to be followed ?
    > POSIX makes no specification of how scheduling classes interact - unless something changed
    > in the new version.
    > But more than that, the problem of preemption is much more complex when you have
    > task that do not share the "goodness fade" with everything else. That is, given a
    > set of SCHED_OTHER processes at time T0, it is reasonable to design the scheduler so
    > that there is some D so that by time T0+D each process has become the highest priority
    > and has received cpu up to either a complete time slice or a I/O block. Linux kind of
    > has this property now, and I believe that making this more robust and easier to analyze
    > is going to be an enormously important issue. However, once you add SCHED_FIFO in the
    > current scheme, this becomes more complex. And with preempt, you cannot even offer the
    > assurance that once a process gets the cpu it will make _any_ advance at all.
    > --
    > ---------------------------------------------------------
    > Victor Yodaiken
    > Finite State Machine Labs: The RTLinux Company.

    Victor Yodaiken
    Finite State Machine Labs: The RTLinux Company.

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