Re: Where to find good doc ?

Le mer 15/12/2004 à 21:02, Philippe Martinole a écrit : 
> Hello everyone,
> 
> I've been looking for a doc on SMP since a while but I can't find what I want.
> Do you know some good doc to read ?
> To be more precese, I want to put all processes on only one cpu except
> nly one real time process on the second cpu.

What you want to do is Asymetric multiprocessing using SMP
(Symmetric Multi-Processor) so SMP doc won't help you so much :))

You may have a look to this rthowto:
http://people.mech.kuleuven.ac.be/~bruyninc/rthowto/
which contains valuable information RT and linux including
SMP aspects.

Regarding linux SMP handling and [soft] realtime you
must know that each process may have a processor affinity
which may be set with the sched_setaffinity syscall.
(beware of glibc moving interface regarding this syscal)

Then each interrupt has its smp_affinity which may
be set using /proc/irq/<num>/smp_affinity

As you can see there is NO standard SMP linux feature to
isolate/reserve one (or several) CPU from being used by
processes.

This kind of behavior may be obtained using either 
sub-kernel approach (RTLinux or RTAI
http://www.aero.polimi.it/~rtai/) or using proprietary
extension such as CPU shielding
http://www.linuxdevices.com/articles/AT8610061752.html
http://linuxdevices.com/files/article030/shielded-cpu.pdf

Hope this helps.

> Thanks,
> 
> Philippe
> 
> 
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-- 
Eric NOULARD
E-mail: [email protected]

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