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SubjectRe: Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.31-7

* Rui Nuno Capela <> wrote:

> xruntrace1-2.6.10-rc2-mm3-RT-V0.7.31-13-*.trc.gz
> - the captured traces, as dumped with script.

> Each trace shows only the first XRUN occurrence on a distinct jackd
> session. Every other trace were triggered and captured after
> restarting jackd.

interesting - the trace shows only a latency of 20-40 usecs. Perhaps the
tracing should be done over two periods?

Could you try to hack alsa_driver.c to do the gettimeofday(1,1) call for
only every second case. Something like this ought to be enough:

static count = 0;

if (!(count++ & 1))

(only one thread accesses this particular variable so there are no
threading issues.)

with this variant there's a 50% chance that we get the trace of the last
2 poll() instances. (and there's a 50% chance that we get only 1 period

in any case, the scripts & approach seems to be almost there, i hope we
only need the above change to see the true source of the xruns.

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