Problems with cyclictest and ps

Hi,

I tried cyclictest under Debian Lenny with Kernel-2.6.23.8-hrt3 and Kernel-2.6.22 as user root. As decribed on the cyclictest-wikipage all cyclictest-tasks run with the scheduler class SCHED_FIFO. I controlled the scheduler class with "ps -ce" and ps showed me SCHED_OTHER for the cyclictest-task.

#> ./cyclictest -t 1 -p 80 -n -i 10000

#> ps -ce | grep cyclic
PID CLS PRI TTY TIME CMD
9693 TS 19 pts/5 00:00:00 cyclictest

I am wondering why cyclictest runs as SCHED_OTHER I expected SCHED_FIFO instead. Any explanations of this behavior are welcome.

Regards,

Phil
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Quoted 17 lines · Phil K.

Hi,

I tried cyclictest under Debian Lenny with Kernel-2.6.23.8-hrt3 and Kernel-2.6.22 as user root. As decribed on the cyclictest-wikipage all cyclictest-tasks run with the scheduler class SCHED_FIFO. I controlled the scheduler class with "ps -ce" and ps showed me SCHED_OTHER for the cyclictest-task.

#> ./cyclictest -t 1 -p 80 -n -i 10000

#> ps -ce | grep cyclic
PID CLS PRI TTY TIME CMD
9693 TS 19 pts/5 00:00:00 cyclictest

I am wondering why cyclictest runs as SCHED_OTHER I expected SCHED_FIFO instead. Any explanations of this behavior are welcome.

Quoted 8 lines

Regards,

Phil
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try "ps -eLc | grep cyclic"

Without the "L" you don't see threads/lightweight processes.

I tried cyclictest under Debian Lenny with Kernel-2.6.23.8-hrt3 and Kernel-2.6.22 as user root. As decribed on the cyclictest-wikipage all cyclictest-tasks run with the scheduler class SCHED_FIFO. I controlled the scheduler class with "ps -ce" and ps showed me SCHED_OTHER for the cyclictest-task.

Hi,

Quoted 5 lines · Phil K.

I tried cyclictest under Debian Lenny with Kernel-2.6.23.8-hrt3 and Kernel-2.6.22 as user root. As decribed on the cyclictest-wikipage all cyclictest-tasks run with the scheduler class SCHED_FIFO. I controlled the scheduler class with "ps -ce" and ps showed me SCHED_OTHER for the cyclictest-task.

I had the same problem using 2.6.23.9-rt12 on Debian Etch (schedutils-1.5.0-1) today. When checking the current state of cyclictest with chrt (chrt -p <pid of cyclictest), it always reported SCHED_OTHER and priority 0.
When I tried to change the scheduling policy and/or priority with chrt it seemed to fail as well (not sure whether it tells the truth though). On the other hand starting cyclictest via chrt did the trick:
"chrt -f 80 cyclictest..."

I can provide further details, when I am closer to the machine in question tomorrow.

Cheers,

Florian

I posted the solution for that problem and described it in the RTWiki(http://rt.wiki.kernel.org/index.php/Cyclictest#FAQ).