From owner-freebsd-smp Wed Nov 7 11:44:18 2001 Delivered-To: freebsd-smp@freebsd.org Received: from mail6.speakeasy.net (mail6.speakeasy.net [216.254.0.206]) by hub.freebsd.org (Postfix) with ESMTP id 69F7D37B41B for ; Wed, 7 Nov 2001 11:44:12 -0800 (PST) Received: (qmail 12076 invoked from network); 7 Nov 2001 19:44:11 -0000 Received: from unknown (HELO laptop.baldwin.cx) ([64.81.54.73]) (envelope-sender ) by mail6.speakeasy.net (qmail-ldap-1.03) with SMTP for ; 7 Nov 2001 19:44:11 -0000 Message-ID: X-Mailer: XFMail 1.4.0 on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <20011107194120.045EA207CF@citi.umich.edu> Date: Wed, 07 Nov 2001 11:44:11 -0800 (PST) From: John Baldwin To: Kevin Coffman Subject: RE: magic switch? Cc: freebsd-smp@freebsd.org Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org On 07-Nov-01 Kevin Coffman wrote: > > I've looked around a bit, but haven't seen this. Is there a "magic > switch" that I can flip to disable all but one processor in an > SMP-enabled kernel on an SMP machine? We'd like to do some > measurements comparing performance of an application running on one cpu > vs. two cpus, without the need to reboot between a UP kernel and SMP > kernel. Is this possible? It's certainly possible, but it's not implemented right now AFAIK. :) I think you could just modify smp_active via a sysctl. However, I'm not sure if the CPU's would resume when you set smp_active back to 1 after clearing it. -- John Baldwin -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message