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    SubjectRe: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4]

    * Paul Davis <paul@linuxaudiosystems.com> wrote:

    > >my main suspicion is that either the main jackd thread itself calls the
    > >kernel where the kernel (unexpectedly for jackd) schedules away for
    > >whatever reason, or that the chain of wakeup in the audio path somehow
    > >gets violated (i.e. a kernel problem). There's one quick thing we could
    >
    > the "max delay" measurement isn't a reflection of the runtime activity
    > of jackd. its simply a measurement of the delay between when jackd
    > expected to be next woken from poll and when it actually was.
    >
    > as you noted, jackd generally goes back to sleep in poll typically a
    > long time before the next interrupt is expected. hence any delay in
    > the wakeup is between the interrupt handler and the scheduler getting
    > jackd's main thread back on the processor. i think.

    this brings up the next question: does the jackd measurement also
    timestamp the time when it calls poll() - hence detecting in-jackd
    processing delays? If yes, which value is this from Rui's stats? If not
    then it might make sense to add it.

    Ingo
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