I have an application that is a cpu emulator. It is for the most part working and without problems.
When the emulated cpu runs a cpu diagnostic that checks timing, there are some time critical issues that I think would be solved by raising my priority with a call to sched_setscheduler() using SCHED_FIFO to keep the cpu for the time of the diagnostic test (usually anywhere from 2 ms to 5 seconds). This would prevent the loss of the cpu at a time critical portion of the test (the diagnostic in question fails intermittantly 1 out of 3 times). I think the failures that have been seen is a quick context switch that causes the interrupt to occur a little faster than is expected (the context switch uses up a little time that the emulated cpu would have executed its software timing loop, hence the count is smaller than expected). I tried calling sched_setscheduler() to set my priority to 1 and the mode to SCHED_FIFO both as root and also with a chmod to suid the small program. The program fails with perror() printing "Operation not permitted" which is EPERM. I would have thought that as a root user this would not happen. I was testing with RH 6.2 and 2.2.14 kernel, is sched_setscheduler() broken in that kernel? Does anyone have a sample bit of code that does the call? Best regards. Tony Preston Cancer is Curable, Ask me why! [EMAIL PROTECTED] 2003-04-03 -- redhat-list mailing list unsubscribe mailto:[EMAIL PROTECTED] https://listman.redhat.com/mailman/listinfo/redhat-list
