On 08/02/2013 01:42 PM, Robert Schwebel wrote:
Before hacking around (which might also lead to interesting solutions),
I would start using a kernel with preempt-rt support and play with the
cpu affinity:
http://lxr.linux.no/#linux+v3.10.4/Documentation/kernel-parameters.txt#L1257
Robert !
Nice to see you here (I do own your "Embedded Linux Handbuch für
Entwickler" :-) )
Thanks for the pointer !
I do already know "preempt-rt", but I was not aware of cpu affinity.
So this might help.
In fact I need a way to do very guaranteed low latency. regarding the
high clock rate (about 1 GHz) modern ARM chips can provide, maybe
preempt-rt with the cpu affinity might be a decent way to go.
The raining questions include
- how to calculate the maximum latency that can be guaranteed ? (i.e.
does the Kernel impose any spinlocks and interrupt disables on the would
be AMP subsystem ?)
- how to assign an interrupt (e.g. a dedicated timer) to the subsystem ?
- Do the interrupts immediately call the ISR of the cpu "under
affinity" or is some additional latency imposed by the Kernel (and how
many cpu cycles at max are needed to enter the ISR) ?
Thanks,
-Michael
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