linuxaudio.org

2012-10-19 15:02, Fons Adriaensen skrev:

quoted text
> Hello all,

>

> My ex-collegues at Alcatel are screaming for help. They want to run

> an app (as root, debatable but that's another story) using SCHED_FIFO

> threads on an openSuSE 11.4 system.

>

> Using the 'default' kernel (which has CONFIG_PREEMPT not set), this

> works. Using the 'desktop' kernel (CONFIG_PREEMPT=y) they get an

> EPERM when trying to start a RT thread, even as root.

>

> As I haven't used SuSE for ages, has anyone an idea of what is

> happening here ?

Try with chrt.
On my laptop with opensuse 11.4 with desktop-kernel. I started "top" as

root.
linux-do4z:~ # ps -up `pidof top`

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND

root     15666  0.4  0.0   8848  1300 pts/19   S+   17:54   0:00 top
linux-do4z:~ # chrt -p `pidof top`

pid 15666's current scheduling policy: SCHED_OTHER

pid 15666's current scheduling priority: 0
linux-do4z:~ # chrt -f -p 20 `pidof top`
linux-do4z:~ # chrt -p `pidof top`

pid 15666's current scheduling policy: SCHED_FIFO

pid 15666's current scheduling priority: 20
check with "chrt -m" for priorities.
regards,
/bengan

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