From owner-freebsd-current@FreeBSD.ORG Tue Jan 20 15:56:39 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0622A1065680 for ; Tue, 20 Jan 2009 15:56:39 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id D38398FC1A for ; Tue, 20 Jan 2009 15:56:38 +0000 (UTC) (envelope-from rwatson@FreeBSD.org) Received: from fledge.watson.org (fledge.watson.org [65.122.17.41]) by cyrus.watson.org (Postfix) with ESMTPS id 7612B46B2E; Tue, 20 Jan 2009 10:56:38 -0500 (EST) Date: Tue, 20 Jan 2009 15:56:38 +0000 (GMT) From: Robert Watson X-X-Sender: robert@fledge.watson.org To: Barney Cordoba In-Reply-To: <844890.15272.qm@web63902.mail.re1.yahoo.com> Message-ID: References: <844890.15272.qm@web63902.mail.re1.yahoo.com> User-Agent: Alpine 2.00 (BSF 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-current@freebsd.org Subject: Re: Running on only some cores X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 20 Jan 2009 15:56:39 -0000 On Tue, 20 Jan 2009, Barney Cordoba wrote: > Can FreeBSD be configured to only run on N cores? So for example, if I have > an 8 core system, can it be configured in loader.conf or through a simple > hack to only run on 2 cores? > > We're testing various configs, and its not terribly convenient to keep > swapping out CPUs. You can use device.hints to disable specific CPUs using: hint.lapic.X.disabled=1 This prevents FreeBSD from probing the CPU. If I had to guess, disabling the BSP would be a bad idea, but for the APs it should work fine. :-) Robert N M Watson Computer Laboratory University of Cambridge