Date: Fri, 27 Jan 2006 11:31:56 -0800 From: Colin Percival <cperciva@freebsd.org> To: Pete French <petefrench@ticketswitch.com> Cc: freebsd-stable@freebsd.org Subject: Re: How do I turn off hyperthreading on 6.0 ? Message-ID: <43DA752C.9000300@freebsd.org> In-Reply-To: <E1F2ZCY-000Dvx-Ey@dilbert.firstcallgroup.co.uk> References: <E1F2ZCY-000Dvx-Ey@dilbert.firstcallgroup.co.uk>
next in thread | previous in thread | raw e-mail | index | archive | help
Pete French wrote: > 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. The way machdep.hlt_logical_cpus works is by telling the scheduler to ignore the extra logical processors, not by pretending that the extra logical processors don't exist at all. (This was necessary to ensure that interrupts could still run on the extra threads -- otherwise some problems appeared with broken BIOSes which couldn't route interrupts correctly.) If you look at top(1), which processors do you see actually running processes? Colin Percival
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?43DA752C.9000300>