Date: Fri, 27 Jan 2006 19:24:06 +0000 From: Pete French <petefrench@ticketswitch.com> To: fcash@ocis.net, freebsd-stable@freebsd.org Subject: Re: How do I turn off hyperthreading on 6.0 ? Message-ID: <E1F2ZCY-000Dvx-Ey@dilbert.firstcallgroup.co.uk> In-Reply-To: <200601271019.59088.fcash@ocis.net>
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> Disable it in the BIOS. The kernel can't use what isn't advertised as > available. :) true - but surely this is a bug in FreeBSD ? man smp says: "Since using logical CPUs can cause performance penalties under certain loads, the logical CPUs can be disabled by setting the machdep.hlt_logical_cpus sysctl to one." I have: websvr04# sysctl machdep.hlt_logical_cpus machdep.hlt_logical_cpus: 1 but I am still seeing 4 CPU's as I have two physical processors, each with two logical ones onboard. I find it very hard to believe theres a bug in something this basic though, as it's specificly mentioned in the relase notes as being there to disable hyperthreading... very odd... -pete.
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