Query on Linux process sheduling

From: B.Vinai Kumar
Date: Sat Mar 24 2012 - 07:56:15 EST


Hi Guys,

I have embedded box running 2.6.28.9 linux kernel and running 6 Real
time task threads (With SCHED_RR as scheduling policy).
Together all the 6 threads running is consuming around 85% of CPU,
which is expected.

All the threads have a 10ms of cycle.

The issue is for every second I have observed that for 50ms these Real
time task threads are not scheduling at all. During this 50ms
the process swapper/idle task is being scheduled(pid 0).

Is this the behaviour is due to these values?

# cat /proc/sys/kernel/sched_rt_period_us
1000000
# cat /proc/sys/kernel/sched_rt_runtime_us
950000

What changes can be done to the kernel so that the Real time task
threads get scheduled in that 50ms interval too?

Thanks,
Vinai.
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