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    SubjectRe: 2.2.1 scheduler behavior


    On Fri, 19 Feb 1999, Rik van Riel wrote:

    > On 18 Feb 1999, Claude Gamache wrote:
    >
    > > We have an application made up of 15 processes that interact
    > > through shared memories and sockets. Each process computes for a
    > > few milliseconds and then pass its data to the next one (a
    > > pipeline computation scheme).
    > [SNIP]
    >
    > > It looks as if the use of the RTC at high frequencies causes the
    > > Kernel scheduler to be executed more often.
    >
    > Andrea, Ingo?

    Just to add my 2c, I noticed the same thing with a little module
    that repeatedly adds itself to tq_immediate and exports a count to
    /proc. It executes either two or four times the interrupt frequency
    depending on whether an application selects on rtc or does a blocking
    read. Isn't that simply due to scheduling on the interrupt and syscall
    returns?

    But I noticed something else curious. When I had apm compiled in
    along with CONFIG_APM_CPU_IDLE, the task would execute between
    30000 to 40000 times per second! Removing apm it went back
    the more "normal" 400 to 600.

    Just wondering is this the expected behavior?


















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