Date: Tue, 10 Mar 2009 22:31:18 +0100 (CET) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-smp@FreeBSD.ORG, Heron <robert@heron.pl>, Julian Elischer <julian@elischer.org> Subject: Re: only one logical CPU used in Xeon Message-ID: <200903102131.n2ALVIjR072494@lurza.secnetix.de> In-Reply-To: <49B697F8.3070301@elischer.org>
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Julian Elischer wrote: > Robert Heron wrote: > > Hyperthreading is enabled in BIOS, but the variable: > > > > machdep.hyperthreading_allowed > > > > is '0' by default in FreeBSD 6.2R :((( > > I just changed it now to '1' and all cores in all CPUs started to work :))) > > > > Very simple change and so much power more :) > > well certainly more power used.. That's true. > It would be a good idea to do benchmarks on your workload > to check if it actually helps. This is is because > Hyperthreading on some cpu models actually reduces throughput > on some workloads because it thrashes the shared cache more. No need for benchmarks here, because Robert's processors don't do hyperthreading at all. FreeBSD 6.2 recognized the *cores* as logical HT processors, so he needs to set hyperthreading_allowed in order to enable the cores. Of course, the better solution is to update to a more recent release, such as 6.4 or even 7.1. His 6.2 is more than 2 years old and contains lots of known bugs, of which the wrong recognition of cores is a relatively harmless one. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd "That's what I love about GUIs: They make simple tasks easier, and complex tasks impossible." -- John William Chambless
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