Le 21/02/2014 18:16, Franz Engel a écrit : > Hi, > > I made a little benchmark of the communication performance of my system > (with Rtnet). Therefore I use an external Data Analyzer (Anritsu) and > measure the delay between each telegram. I tried to send every 4ms. Pseudo > code: > > while(true): > > ret=sendto(...) > > sleep(4ms) > > endwhile
If you really want to send a message every 4ms, this is not what you should do. What you should do is either use an absolute delay, or make the task periodic. Otherwise, the errors will add-up. > > I make this test two times. One time with a totally unstressed system. That > means I isolated the specific core, where my real-time task is working, and > there are no other running programs. The result is that the mean delay of my > communication was 0,004003518. > > For the second test I stressed my system with "taskset -c 0-11 stress --cpu > 12" (that means each core is working with 100%). Now I have the funny > effect, that the result of the second test is better than the first one. In > the second test I have an mean delay of 0,004000951. That means, the mean > delay of the stressed system is 2.567 micro seconds faster than the > unstressed system. > > Does somebody have an idea what could be the reason for this phenomenon? Sounds like a problem with power management. Maybe C1E mode on recent intel processor? -- Gilles. _______________________________________________ Xenomai mailing list [email protected] http://www.xenomai.org/mailman/listinfo/xenomai
