Hi, I'm writing since i am experiencing some difficulties through the development of an application which execute a cyclic task every 1 ms. The computer where this application should run is an embedded pc with an intel celeron j1900 quad core, 2G of ram and 32G of ssd. I have installed debian 9.2.1 on it, from a netinst iso image, with no graphical environment. I've downloaded the latest stable kernel source (4.9.47) with the respective rt patch (4.9.47-rt37) and followed the instructions as described in the web page "how to set up preempt_rt properly". I patched the kernel and then i ticked the box with the "Fully Preemptible Kernel" option, and compiled it (make, make modules_install, make install). Rebooted the pc, i checked that the new kernel was running (uname -a) and i wrote a small cpp application following the example of "how to build a simple rt application" web page and "how to build a basic cyclic application" web page. Then to be sure that the cycle keeps at a constant rate of 1 ms, i took the time in nano seconds (clock_gettime) each time the thread finished sleeping and woke up, and compared it with the previous woke up time by subtraction. In theory i should get this time to be around 1000000 ns, but what i get is that it varies continuosly from 800000 to 1100000. Sometimes when i launch the program it stays around the desired cycle time, but if i stop and restart the program then it starts to behave as before. I am really confused, what am i doing wrong or am i missing to do? Any suggestion is appreciated. Thanks in advance. -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
