>
> one piece of information that Ganglia collects for a node is the
> "number of CPUs", originally meaning "physical CPUs".
Ok I was afraid of that.
> 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.
I think that decision is a mistake, and is probably based on experiences
with the first generation of HT capable Pentium 4 processors.
The original p4 HT to a large degree suffered from a too small cache
that now was shared. SMT in general isn't per se all that different in
performance than dual core, at least not on a fundamental level, it's
all a matter of how many resources each thread has on average. With dual
core sharing the cache for example, that already is part HT. Putting the
"boundary" at HT-but-not-dual-core is going to be highly artificial and
while it may work for the current hardware, in general it's not a good
way of separating things (just look at the PowerPC processors, those are
highly SMT as well), and I suspect that your distinction is just going
to break all the time over the next 10 years ;) Or even today on the
current "large cache" P4 processors with HT it already breaks. (just
those tend to be the expensive models so more rare)
I would strongly urge you to reconsider this decision; if you want to
show "sockets" that sounds reasonable, or even if you want to do it on
the "bus sharing" level (FSB/HT), but HT.. just sounds wrong.
--
if you want to mail me at work (you don't), use arjan (at) linux.intel.com
Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org
-
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/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
