Re: Hypertherading

From: Barney Cordoba <barney_cordoba_at_yahoo.com>
Date: Thu, 7 May 2009 06:57:44 -0700 (PDT)
--- 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
Received on Thu May 07 2009 - 11:57:45 UTC

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