I am having the same problem. Anyone have any advice? On Wednesday, April 10, 2013 4:03:20 PM UTC-4, edj wrote: > > I'm looking for a means to do real-time scheduling on a BeagleBone with > the Angstrom distro. Is it possible? I've been trying, but failing... > > Whenever I try programmatically using pthread_setschedparam, I get > "Operation not permitted" errors even when logged in as root. > > When I try with the "chrt" command to change a process to use SCHED_FIFO, > it reports back that the process is using SCHED_OTHER, effectively ignoring > my request. > > If real-time is not possible with Angstrom, can anyone recommend a quick > path to get there with another distro or add-on to Angstrom? > > I have one simple real-time requirement. I need to detect an edge of a > GPIO signal and take an action within 1 millisecond of that edge, > guaranteed. I'm doing this with user space GPIO calls, blocking a thread > waiting on a GPIO edge event. I'm measuring response time by watching > another GPIO that I assert when the sleeping thread wakes up. Without > real-time scheduling, many edge events are detected and responded to in > under 1 ms, but the worst case time is sometimes as long as 20 > milliseconds. I could live with 2 or 3 ms, if reliable, but 20 ms is just > too slow for my application. > > Would a kernel module doing the same job experience better worst-case > response times? > > Thanks, > Ed >
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