From owner-freebsd-stable@FreeBSD.ORG Fri Jan 27 19:32:04 2006 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4D17116A420 for ; Fri, 27 Jan 2006 19:32:04 +0000 (GMT) (envelope-from cperciva@freebsd.org) Received: from pd2mo2so.prod.shaw.ca (shawidc-mo1.cg.shawcable.net [24.71.223.10]) by mx1.FreeBSD.org (Postfix) with ESMTP id CF97543D48 for ; Fri, 27 Jan 2006 19:32:03 +0000 (GMT) (envelope-from cperciva@freebsd.org) Received: from pd2mr5so.prod.shaw.ca (pd2mr5so-qfe3.prod.shaw.ca [10.0.141.8]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0ITR003V7NLBEP70@l-daemon> for freebsd-stable@freebsd.org; Fri, 27 Jan 2006 12:31:59 -0700 (MST) Received: from pn2ml5so.prod.shaw.ca ([10.0.121.149]) by pd2mr5so.prod.shaw.ca (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0ITR0056KNLBO720@pd2mr5so.prod.shaw.ca> for freebsd-stable@freebsd.org; Fri, 27 Jan 2006 12:31:59 -0700 (MST) Received: from [192.168.0.60] ([24.87.209.6]) by l-daemon (Sun ONE Messaging Server 6.0 HotFix 1.01 (built Mar 15 2004)) with ESMTP id <0ITR003ETNLAB6N0@l-daemon> for freebsd-stable@freebsd.org; Fri, 27 Jan 2006 12:31:59 -0700 (MST) Date: Fri, 27 Jan 2006 11:31:56 -0800 From: Colin Percival In-reply-to: To: Pete French Message-id: <43DA752C.9000300@freebsd.org> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1 Content-transfer-encoding: 7bit X-Enigmail-Version: 0.94.0.0 References: User-Agent: Thunderbird 1.5 (X11/20060112) Cc: freebsd-stable@freebsd.org Subject: Re: How do I turn off hyperthreading on 6.0 ? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Jan 2006 19:32:04 -0000 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