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    SubjectRe: v2.6.19-rt1, yum/rpm

    * Karsten Wiese <fzu@wemgehoertderstaat.de> wrote:

    > I tweaked latency_trace.c to make freerunning work. Will post later.

    ok, please do.

    i'm trying to understand your trace:

    > Below the trace shows i_usX2Y_usbpcm_urb_complete() running under an
    > alien context, and this is where jackd starts stalling:

    by 'alien context' do you mean softirq--4? That is the following kernel
    thread:

    4 ? S 0:00 [softirq-high/0]

    handling HI_SOFTIRQ softirqs, which are the 'highprio' tasklets.

    > IRQ_17-308 0D..2 3411063us : deactivate_task <IRQ_17-308> (180 2)
    > softirq--4 0D..2 3411064us+: __schedule <IRQ_17-308> (180 101)
    > softirq--4 0.... 3411072us+: i_usX2Y_usbpcm_urb_complete (8 0 dd134)
    > softirq--4 0.... 3411078us : try_to_wake_up (c011b4ab 0 0)
    > softirq--4 0D..1 3411079us : __activate_task <jackd-2667> (173 1)
    > softirq--4 0Dn.1 3411079us : try_to_wake_up <jackd-2667> (173 101)
    > softirq--4 0Dn.1 3411080us : __schedule (c032a862 0 0)
    > jackd-2667 0D..2 3411081us+: __schedule <softirq--4> (101 173)

    it's running at SCHED_FIFO prio 80.

    it's probably this use in sound/usb/usbmidi.c:

    tasklet_hi_schedule(&port->ep->tasklet);

    so what is your observation - if i_usX2Y_usbpcm_urb_complete() is
    executed in this tasklet then you are seeing xruns/delays?

    Ingo
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