On 11/11/2012 8:53 AM, Michael Haberler wrote:
> I've worked on Xenomai userthreads build and it is now ready for early testers
>
> <...>
>
> This works on both the 2.6.38.8 and 3.2.21 xenomai kernels, recompilation not 
> needed.

Michael, I meant to ask. Do you see any significant difference in the 
two kernels? I've been using your 3.2.21 kernel only.

> This build wiggles parport pins on my atom; there are still isolated realtime 
> delays, and reporting of those needs improvement.
>
> The parport driver at this point uses the portable but slower ppdev ioctl 
> method; work is underway to enable direct inport/outport I/O if supported by 
> the architecture.
>
> This is now sufficiently mature that development of all RTOS support can 
> happen in a single branch.
>
> for the daring: 
> http://git.mah.priv.at/gitweb/emc2-dev.git/shortlog/refs/heads/rtos-integration-preview1


I built your latest and greatest on my quadcore AMD box a few minutes 
ago: Ubuntu 10.04LTS, 3.2.21-xenomai+ kernel. I also built it on my 
Toshiba NB-305 netbook with dual-core atom N450: Linux Mint 13, 
3.2.21-xenomai+ kernel.

Very preliminary indications are that with xenomai-user threads, I also 
get better jitter numbers, both lower and more stable, than with 
xenomai-kernel on my quadcore. I still see the blowup when I cat 
/proc/xenomai/stat but that may be just an ASUS+Athlon II thing because 
it does not occur on my atom-equipped netbook (which, however, has 
crappy jitter for other reasons). I haven't had time to try any of your 
xenomai work on my ASUS atom motherboard.

Curiously, I get better jitter results on the quadcore if I run both 
latency-test threads on cpu 0, e.g., a core that is exposed to the Linux 
scheduler, than on isolated cpus 2 and 3. On the other hand, 
latency-test running entirely on cpu 0 is somewhat more sensitive to me 
starting other processes, like glxgears, but the effect seems to be 
restricted to a few microseconds accumulated the first time I start up 
glxgears (maybe due to fetching glxgears from the disk?---I should try 
again with a solid-state disk).

Like I said, this is very preliminary. At the least, it shows that 
everything builds reliably from your repo in various environments.

I admit I was skeptical about the user-thread work but this is beginning 
to look like a winner. After 30 minutes, my quadcore is still showing 
max jitter less than 15us  (1ms slow thread) 20us (25us fast thread) 
with both threads running on cpu 0. During the same time, I've been 
running several copies of glxgears, surfing the web, and running find 
over the whole filesystem. RTAI performance on isolated cores is better 
yet, but we all know the long-term problem with RTAI.

Regards,
Kent







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