Hello,
I know this is in the border line with off-topic, since my question
is not exactly about how to develop for the kernel but about how the
kernel works. Please forgive me if my question is not appropriate.
I want to know if it's possible to create a real-time process with
SCHED_FIFO policy that starts running and never lets any other process
run again.
I had read that processes in SCHED_FIFO usually run until a) they block
themselves by calling some syscall (for example, an I/O request), b)
they are preempted by some higher priority process or c) they decide to
yield the processor. So I thought that technically it would be possible
to create a process that "takes over" the processor from all the other
processes: Just create a SCHED_FIFO process that loops infinitely.
However, when I tried this it didn't work. Someone told me about
sched_rt_runtime_us and sched_rt_period_us, which acted like a
protection for this cases. So I tried both setting sched_rt_runtime_us
to -1 and setting both values to the same number, but it didn't work
either: I can switch to another terminal, execute top and see the
process running.
I've tried everything both in Linux 2.6.27-16-server and
2.6.32-22-generic, the first on a VM with one core and the second on my
computer with two cores (when I tried this one I created two real-time
processes instead of one).
What am I doing wrong? Is there some option in the kernel I have to
enable/disable?
Thanks,
--
Pablo Antonio (AKA crazy2k)
http://www.pablo-a.com.ar/
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