On 11/2/2012 5:53 PM, Kent A. Reed wrote:
> <...>
> The good news-
>
> LinuxCNC built for xenomai-kernel threads without a hitch. I love how 
> fast a build goes with make running on multiple cores.
>
> Since this is a quadcore system, I set isolcpus=3 and rebooted into 
> 3.2.21-xenomai+
>
> The not so good news-
>
> I'm seeing the same sort of strange behavior I saw with the RT-PREEMPT 
> patches earlier although not as strongly.
>
> RTAI - 1ms servo thread/25us base thread - max jitter 4401ns/2378ns 
> after 3 hours
>
> Xenomai/kernel - 1ms servo thread/25us base thread - max jitter 
> appeared to be running roughly 10000ns/10000ns after 45 minutes *but* 
> then while I was doing something random the max jitter jumped to 
> 89590ns/367129ns (at which point /proc/xenomai/stat said wait 
> errors=8. last overrun=14, total overruns=76). Later, I reran the test 
> unattended for an hour and again got roughly 10000ns/10000ns max 
> jitter. Which is good but the burst is worrisome.

The "something random" turns out to be executing "cat 
/proc/xenomai/stat" in a separate terminal while running latency-test. 
This operation reliably kicks the reported max-jitter number over the 
moon. Looking at /proc/rtapi/status doesn't seem to be a problem.

Hope this helps.

Regards,
Kent



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