Re: getting processor numbers

From: Paul Jackson
Date: Tue Apr 03 2007 - 22:59:07 EST


Ulrich wrote:
> But all this of course does not solve the issue sysconf() has. In
> sysconf we cannot use sched_getaffinity since all the systems CPUs must
> be reported.

Good point. Yes, sysconf(_SC_NPROCESSORS_CONF) really needs to continue
returning the number of CPUs online, to maintain compatibility with the
current implementation, and because with a name like that, just about
anything else would be "surprising".

And OpenMPI shouldn't be calling sysconf(_SC_NPROCESSORS_CONF), as it does
not want to know how much hardware is there, but rather how much hardware
it is allowed to use. Something based on sched_getaffinity() would seem
to be ideal for its purposes.

--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <pj@xxxxxxx> 1.925.600.0401
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