On Thu, Dec 13, 2018 at 09:27:12PM +0000, Paul Swanson wrote: > Hi, > > I'm trying to understand how interval timers work in OpenBSD, > but I'm a little stuck on this line from the getitimer / setitimer man page: > > "Time values smaller than the resolution of the system clock > are rounded up to this resolution (typically 10 milliseconds)." > > Does this mean that 10 milliseconds is the shortest interval possible > with a system interval timer? > > If so, are there other userland options for more precise timers? >
What would need a more precise timer? with what resolution? On amd64, you could build a kernel with HZ=1024, which gives a timer that ticks every 1ms. I use this since ~2005 for MIDI programs. If the program that needs a precise timer involves audio, you could also use the sound card clock instead. For instance by running sndiod with "-z 120" option then call your code in the sio_onmove(3) call-back. The advantage of this approach is that you get a unique clock source, which avoids may problems.
