I'm having a problem getting realtime priorities working, and I'm wondering if anyone has any suggestions. I'm running Slackware, which doesn't use PAM, so I'm starting everything with the set_rlimits command. I thought I had it working once, but the next time I booted the system, I couldn't get it working again, and I'm not sure what has changed in the meantime. I'm still in the process of compiling and installing things, so I might have changed something, but I'm not sure what. Here's what I have in the /etc/set_rlimits.conf file for jackd and qjackctl, for example: @audio /usr/bin/jackd nice=40 rtprio=70 memlock=262144 @audio /usr/bin/qjackctl nice=40 rtprio=70 memlock=524288 After starting qjackctl, which in turn starts jackd, checking my realtime priorities shows this: chuck@lambda:~% ps -eo pid,rtprio,cls,cmd | grep jack 16524 - TS /usr/bin/qjackctl -p HDA 16531 - TS /usr/bin/jackd -v -P70 -t2000 -dalsa -dhw:Intel -r48000 -p1024 -n2 -Xseq -i2 -o2 -I1 -O1 30333 - TS grep jack This is with the laptop's internal sound card, but I get the same results with my RME Multiface (except that the -d, -i, and -o options to jackd are different, of course). I can change the realtime priority with chrt, but I shouldn't have to. That should be taken care of by set_rlimits. As an experiment, I added this to the configuration file: @audio /bin/zsh nice=40 rtprio=99 memlock=5000000 I then get the following results with zsh (I also tried with bash, with the same results, but a slightly different output format): chuck@lambda:~% ulimit -erl -l: locked-in-memory size (kb) 64 -e: max nice 0 -r: max rt priority 0 chuck@lambda:~% set_rlimits zsh -i chuck@lambda:~% ulimit -erl -l: locked-in-memory size (kb) 5000000 -e: max nice 40 -r: max rt priority 99 chuck@lambda:~% ps -eo pid,rtprio,cls,cmd | grep 'zsh -i' 30359 - TS /bin/zsh -i 30367 - TS grep zsh -i It looks like set_rlimits is working until I look at the realtime priority with ps. What am I doing wrong? I might add that the priorities being set for the IRQs by rtirq are being set correctly, but of course rtirq uses chrt. All this is with a realtime kernel, of course: chuck@lambda:~% uname -srv Linux 3.0.1-rt11 #1 SMP PREEMPT RT Wed Aug 24 05:48:12 EDT 2011