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

[Rui Nuno Capela]

> 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@xxxxxxxxx

Attachment: config-2.6.10-rc2-mm3-RT-V0.7.31-15.gz
Description: application/gzip-compressed

Attachment: xruntrace1-2.6.10-rc2-mm3-RT-V0.7.31-15-20041130140917.trc.gz
Description: application/gzip-compressed

Attachment: xruntrace1-2.6.10-rc2-mm3-RT-V0.7.31-15-20041130141834.trc.gz
Description: application/gzip-compressed

Attachment: xruntrace1-2.6.10-rc2-mm3-RT-V0.7.31-15-20041130142405.trc.gz
Description: application/gzip-compressed

Attachment: jackit-0.99.15.1xruntrace-alsa.patch.gz
Description: application/gzip-compressed