Hello, I am working with a group on PortAudio, a simple cross-platform open-source audio API. We currently support Windows, Mac, BeOS, SGI, and, of course, Unix.
Folks have been reporting audio glitches even with a buffer size equivalent to 100 msec. I have experimented with setting my thread priority to the max for SCHED_FIFO and that seems to eliminate the glitches. I can get down to around 5 or 10 msec latency on RedHat 7.2, even without any low-latency patches. But I have to run as superuser. I have heard reports that SCHED_FIFO has several bugs. I have searched the web and read many posts about this but there are still unanswered questions. Q: Do the SCHED_FIFO bugs prevent a simple use of sched_setscheduler() to bump the priority of a thread that is reading and writing to OSS? I want the code to work on old systems as well as new. Q: Does SCHED_RR work better than SCHED_FIFO? Fewer bugs? Q: I have code that throttles back if I consume too much CPU time. Is that sufficient? Q: Can I safely use the value from sched_get_priority_max(SCHED_FIFO) or should I use less? Thanks, Phil Burk JSyn,pForth,DSP,ASIC - http://www.softsynth.com Portable Audio I/O - http://www.portaudio.com Interaction Server - http://www.transjam.com
