On Sat, 2006-02-25 at 02:44 -0500, Hector Centeno-Garcia wrote: > Hi, > > I've been playing around a little with the priority thing. I would like > to understand better the way it works. Looking at the priority of jackd > (running realtime, as user, and with a RT kernel, full-preemption) I > can't figure out why if I start jackd with -P 60 (or any other number > > 0) the output of chrt is always: > > $ chrt -p (jackd's pid) > pid 8115's current scheduling policy: SCHED_OTHER > pid 8115's current scheduling priority: 0 > > I checked this in two different distros (FC4+CCRMA and Ubuntu with > custom RT kernel) and the result is the same. Is it not supposed to read: > > $ chrt -p 8115 > pid 8115's current scheduling policy: SCHED_FIFO (maybe?) > pid 8115's current scheduling priority: 60 > > I know that I can set this manually, but I'm just wondering what is the > real effect of the -P flag. > > Any help will be appreciated, Assuming you did start Jack with the "-R" option you are probablyk looking at the main Jack process and that is actually SCHED_OTHER. Jack has more threads and some of them are SCHED_FIFO. Do this: ls /proc/(jack's pid)/tasks and you will see the pids of the other threads (I'm sure there must be a more elegant way of finding this info) A chrt of those will show something like this: $ for pid in `ls /proc/27701/task/` ; do chrt -p $pid ; done pid 27701's current scheduling policy: SCHED_OTHER pid 27701's current scheduling priority: 0 pid 27702's current scheduling policy: SCHED_OTHER pid 27702's current scheduling priority: 0 pid 27703's current scheduling policy: SCHED_OTHER pid 27703's current scheduling priority: 0 pid 27704's current scheduling policy: SCHED_FIFO pid 27704's current scheduling priority: 72 pid 27705's current scheduling policy: SCHED_FIFO pid 27705's current scheduling priority: 62 And there you have the rt threads... -- Fernando
