On Wed, 2004-06-02 at 12:11, Fernando Pablo Lopez-Lezcano wrote: > On Wed, 2004-06-02 at 11:34, Arjan van de Ven wrote: > > On Wed, Jun 02, 2004 at 11:28:20AM -0700, Fernando Pablo Lopez-Lezcano wrote: > > > > > > A real test with the Jack low latency server reveals that something else > > > > > > is creating latency hits. > > > > > > > > > > do you run Jack as realtime process ?? > > > > > > > > Correct, it is running SCHED_FIFO. I'm using Jack O'Quin LSM realcap > > > > module to grant non-root users those privileges (compiled as a module in > > > > the kernel). > > > > > > > > Just occured to me, is there anything else in FC2 that may be running > > > > SCHED_FIFO?? I'll try to find out. > > > > > > Using schedutils (chrt) I find no tasks or threads running SCHED_FIFO. > > > And the realtime threads of jack are apparently running SCHED_FIFO. > > > Argh, that would have been too easy :-) > > > > can you try to NOT run it realtime? > > Sure, just tried that. Lots _more_ xruns, move around the mouse, xruns, > switch windows, xruns :-) > > > Sounds odd but when you use realtime > > behavior you have to be really careful for priority inversion situations (eg > > if X doesn't run at such a high prio, but your RT task needs to wait on X to > > draw something..) > > Aha! I think you are on to something! I double checked the priority of > the jack clients and _they_ are not getting SCHED_FIFO!! They should be > getting that priority from the jack server but they are not (and the > jack server is not complaining at all so no error is being raised). > Probably some change in glibc, I would think... Before (or rather while) I start banging my head again against sched_setscheduler and friends, could this be related to selinux even though it is turned off? None of the calls that are supposed to give the client thread SCHED_FIFO are (apparently) returning errors... -- Fernando
