Hi Drew, Without the real time kernel, I didn't need to put any additional load and I could see the jitter was large (on x86 in a VM). As soon as I did any activity such as just open another terminal, the jitter shot even higher, so I didn't deliberately add any further load, since it was clear I couldn't do much machine control in this manner.
I've just now repeated with BBB, and recorded a couple of videos (each video is less than 2Mbyte, MP4 file). They are here to download: https://app.box.com/s/hcax6malowe43ctxdg1x64r83yruklyg In the no-xenomai-gcc.mp4 video, you can see that I ran the cyclic test which shows the Min/Actual(i.e. current)/Avg/Max latency values in usec. I ran gcc as a real-world load. You can see that the latency shoots up to 591 usec, i.e. jitter is higher than 500 usec. In the with-xenomai-gcc.mp4 file, I repeat things, but this time using a cyclic test which is xenomai-enabled. The video shows that the latency during the gcc load didn't exceed 62 usec, so almost 10 times better : ) There's a third video there too, titled stress-xenomai.mp4. In that, I ran a stress command, and also displayed the processes and top. Afterwards, I stopped the cyclic test and you can see the difference in 'top' output too. I don't know how useful this video is, because I don't know how good that stress command is. I copied that command from some Pi stress-test document. Thanks, Shabaz. ________________________________ From: [email protected] <[email protected]> on behalf of Drew Fustini <[email protected]> Sent: 23 October 2019 11:53 To: Beagle Board <[email protected]> Subject: Re: [beagleboard] Re: Real Time experience on Beagle? On Tue, Oct 15, 2019 at 6:16 PM shabaz <[email protected]> wrote: > By the way, > > I've put an oscilloscope trace of a Xenomai'd program on the BBB here in case > you'd like to show it for your presentation: > https://app.box.com/s/nfwlud613c7zoz7gu6rn9arfttticvvc > > For that trace, the BBB is just toggling a GPIO pin repeatedly, in a > Xenomai'd thread. I left it running for several minutes and the statistics > that were collected are at the bottom of the screenshot. > The delta between the Max (66.34 usec) and Min (60.76 usec) values indicates > that jitter was under 6 usec. Thanks very much for these instructions and your results. I will give a try. Did you run anything to put load on the system while you were collecting stats? thanks, drew -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAEf4M_CxW3m1QVennDZz%2Bu_fpUbxjDdOsi1Tt0DEur1td70dLw%40mail.gmail.com. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/DB6P18901MB0214F24846A34FD0CB0B9B9E846B0%40DB6P18901MB0214.EURP189.PROD.OUTLOOK.COM.
