--- Arjan van de Ven <[EMAIL PROTECTED]> wrote: > On Wed, 2006-12-27 at 06:16 -0800, Martin Knoblauch wrote: > > Hi, (please CC on replies, thanks) > > > > for the ganglia project (http://ganglia.sourceforge.net/) we are > > trying to find a heuristics to determine the number of physical CPU > > "cores" as opposed to virtual processors added by enabling HT. The > > method should work on 2.4 and 2.6 kernels. > > I have a counter question for you.. what are you trying to do with > the > "these two are SMT sibblings" information ? > > Because I suspect "HT" is the wrong level of detection for what you > really want to achieve.... > > If you want to decide "shares caches" then at least 2.6 kernels > directly > export that (and HT is just the wrong way to go about this). > -- Hi Arjan,
one piece of information that Ganglia collects for a node is the "number of CPUs", originally meaning "physical CPUs". With the introduction of HT and multi-core things are a bit more complex now. We have decided that HT sibblings do not qualify as "real" CPUs, while multi-cores do. Currently we are doing "sysconf(_SC_NPROCESSORS_ONLN)". But this includes both physical and virtual (HT) cores. We are looking for a method that only shows "real iron" and works on 2.6 and 2.4 kernels. Whether this has any practial valus is a completely different question. Cheers Martin ------------------------------------------------------ Martin Knoblauch email: k n o b i AT knobisoft DOT de www: http://www.knobisoft.de - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
