Hi!
On 02:01 Sat 28 Aug , Pablo Antonio wrote:
...
> 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.
Yes, it should be. However hardware interrupts will still arrive.
> 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.
This is weird. Are you sure that you have put the process in the SCHED_FIFO
queue and assigned a static priority > 0 via sched_setscheduler? If you start
top and look in the PR column you should see "RT".
> What am I doing wrong? Is there some option in the kernel I have to
> enable/disable?
I do not think that there is an option about this.
-Michi
--
programing a layer 3+4 network protocol for mesh networks
see http://michaelblizek.twilightparadox.com
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