Date: Tue, 27 May 2008 12:14:37 +0200 (CEST) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-questions@FreeBSD.ORG, s.hattori@scs.co.jp Subject: Re: FreeBSD 7.0-RELEASE: Can I specify the maximum number of cores that ?kernel can recognize ? Message-ID: <200805271014.m4RAEb6W032484@lurza.secnetix.de> In-Reply-To: <011501c8bfcc$a3164b40$c154140a@colors.scs.co.jp>
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Hattori, Shigehiro wrote: > I try to measure Bind caching name server's multi threading performance on > FreeBSD 7 , like below. > [...] > My testing machine has 8 cores. ( quad core * 2 ) > > I'd like to specify the maximum # of cores that kernel can recognize. > Can I specify the maximum # of cores with boot parameters or something ? You can reduce the MAXCPUS constant. The default is 16 on i386 and amd64. Unfortunately you have to modify a header file and recompile your kernel. The MAXCPUS constant can be found in /sys/$ARCH/include/param.h and is installed as /usr/include/machine/param.h. After reboot you can verify the new value with sysctl kern.smp.maxcpus (it's a read-only value). 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 "One of the main causes of the fall of the Roman Empire was that, lacking zero, they had no way to indicate successful termination of their C programs." -- Robert Firth
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