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Subject: Re: [hwloc-devel] PUs not located under cores
From: Samuel Thibault (samuel.thibault_at_[hidden])
Date: 2010-06-24 12:28:18

Jeff Squyres, le Thu 24 Jun 2010 12:02:48 -0400, a écrit :
> Is that right? I.e., is it proper that hwloc can return just a pile of PUs under a numa node with no core as an umbrella?

Yes, that happens when the kernel doesn't know where cores are. In that
case you thus can't know whether the proc is hyperthreaded or not.

> It might be worth adding a section in hwloc.doxy describing stuff like this (yes, I'm volunteering to write it :-) )

Please do.

> depending on the type of machine you're running on.

It also depends on the OS and kernel version for instance. Not all
information is available, the only you can bet on is PUs under a system
object. At worse there is just one because the OS didn't even say how
many there are.