Re: Need help to measure and tune the latency in Linux RT
Jason Cooper <[email protected]>
| Newsgroups | org.kernel.vger.linux-newbie,org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-embedded,org.kernel.vger.linux-rt-users |
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| Message-ID | <[email protected]> |
Ashoka, linux-embedded is pretty quiet. I'm not even sure why I'm still subscribed to it. You'll have better luck with your question by asking on linux-arm-kernel (added to the cc). I believe there is also a linux-rt-users mailinglist [1]. A few comments below: On Tue, Apr 30, 2013 at 01:57:21PM +0530, Ashoka K wrote: > Hi, > > I have an embedded system running 2.6.33 cross compiled for ARM OMAP > with 1 GHZ uni-processor system. Wow, this is ancient. Is this a vanilla kernel? If it's a vendor kernel, you'll need to ask the vendor. > The application has many threads and processes (around 15 total). In > that 1 thread is time critical and must run every interval confiurable > as 2, 4 or 8 milli sec etc. There is another thread which transfers > Images to a FTP or to HMI etc, whoever requested the image. > With this image transfer enabled my critical process misses the > deadline and timesout. This critical thread is at RR priority 50. I > used a HR timer thread with RR pri 55 to wakeup the critical thread > every 1 milli sec to do the job. > If image transfer is enabled i see that real time thread misses deadlines. > > All traffic is flowing on common ethernet connection. Does it affect > in any way ? > > How to find out where the kernel is waiting or delaying to schedule > the critical thread even though it is at higher RR priority. How to > measure the latency ? > > I am trying to use Oprofile tool, but got some error in cross > compiling. Doesn't these tools add their own latency to the original > problem ? > > Any tools ? which one is better. Please provide your input on this. I'm not the guy to answer this ;-) I'll just forward to the appropriate lists. hth, Jason. [1] http://vger.kernel.org/vger-lists.html#linux-rt-users -- To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs