From: Arjan van de Ven <arjan@infradead.org>
To: knobi@knobisoft.de
Cc: Gleb Natapov <glebn@voltaire.com>, linux-kernel@vger.kernel.org
Subject: Re: How to detect multi-core and/or HT-enabled CPUs in 2.4.x and 2.6.x kernels
Date: Wed, 27 Dec 2006 16:53:26 +0100 [thread overview]
Message-ID: <1167234806.3281.3966.camel@laptopd505.fenrus.org> (raw)
In-Reply-To: <20061227154158.54796.qmail@web32608.mail.mud.yahoo.com>
>
> this is a real interesting question. Ganglia is coming [originally]
> from the HPC side of computing. At least in the past HT as implemented
> on XEONs did help a lot. Running two CPU+memory-bandwith intensive
> processes on the same physical CPU would at best result in a 50/50
> performance split. So, knowing how many "real" CPUs are in a system is
> interesting to us.
but this 50/50 split is most likely because of either a cache or a
bandwidth bottleneck, at which point "HT" is the wrong measure.
(also if you go to things like SUN's Niagara CPU then it's even more
clear that SMT isn't the right measure for performance capability)
--
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
next prev parent reply other threads:[~2006-12-27 15:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-27 14:16 Martin Knoblauch
2006-12-27 14:24 ` Arjan van de Ven
2006-12-27 14:40 ` Martin Knoblauch
2006-12-27 15:13 ` Arjan van de Ven
2006-12-27 15:22 ` Gleb Natapov
2006-12-27 15:38 ` Arjan van de Ven
2006-12-27 15:41 ` Martin Knoblauch
2006-12-27 15:53 ` Arjan van de Ven [this message]
2006-12-27 15:51 ` Martin Knoblauch
2006-12-27 16:09 ` Arjan van de Ven
2006-12-27 17:14 ` Bernd Eckenfels
2006-12-27 17:52 ` Martin Knoblauch
2006-12-27 19:58 ` Siddha, Suresh B
2006-12-27 14:37 ` Jan Engelhardt
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