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SubjectRe: Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.31-7
From
> Ingo Molnar
>
> * Rui Nuno Capela wrote:
>
>> xruntrace1-2.6.10-rc2-mm3-RT-V0.7.31-13-*.trc.gz
>> - the captured traces, as dumped with xruntrace1_watch.sh
>> 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))
> gettimeofday(0,1);
> }
>
> (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
> covered.)
>
> 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.
>

Done that.

New XRUN traces are attached, while running RT-V0.7.31-15 now. However, I
don't seem to get any notorious difference on the results, since previous
ones. All latencies traced ca. 26-27 usecs.

Bye.
--
rncbc aka Rui Nuno Capela
rncbc@rncbc.org[unhandled content-type:application/x-gzip-compressed][unhandled content-type:application/x-gzip-compressed][unhandled content-type:application/x-gzip-compressed][unhandled content-type:application/x-gzip-compressed][unhandled content-type:application/x-gzip-compressed]
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