Barney Cordoba wrote: > > > --- On Wed, 5/6/09, pluknet <pluknet_at_gmail.com> wrote: > > >> From: pluknet <pluknet_at_gmail.com> >> Subject: Re: Hypertherading >> To: "Barney Cordoba" <barney_cordoba_at_yahoo.com> >> Cc: "Current_at_freebsd.org" <Current_at_freebsd.org> >> Date: Wednesday, May 6, 2009, 10:55 PM >> 2009/5/7 Barney Cordoba <barney_cordoba_at_yahoo.com>: >> >>> I just got a shiny new nehalem box and it comes up >>> >> with 16 processors with dual quads installed. Is there any >> benefit or should hyperthreading be disabled? >> >> Hi. There is a measurable win if hyperthreading is enabled >> [1]. >> You can switch it off via machdep.hyperthreading_enabled >> loader tunable. >> >> [1] >> http://lists.freebsd.org/pipermail/freebsd-stable/2009-January/047460.html >> >> >> -- >> wbr, >> pluknet >> > > I assume you mean hyperthreading-allowed? > > I set > > sysctl -a | grep hyper > > machdep.hyperthreading_allowed: 0 > > > but it still launches 16 cpus. Is that expected? It doesn't seem correct. > > Barney > > > > _______________________________________________ > freebsd-current_at_freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org" > If I recall correctly, that sysctl only prevents processes from being scheduled on the "virtual" hyper-threaded CPUs, and does not affect their discovery by the kernel. -BorisReceived on Thu May 07 2009 - 14:38:13 UTC
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