From owner-freebsd-questions@FreeBSD.ORG Wed Jan 12 17:51:59 2005 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id B674916A4CE for ; Wed, 12 Jan 2005 17:51:59 +0000 (GMT) Received: from aiolos.otenet.gr (aiolos.otenet.gr [195.170.0.23]) by mx1.FreeBSD.org (Postfix) with ESMTP id 802E043D1D for ; Wed, 12 Jan 2005 17:51:57 +0000 (GMT) (envelope-from keramida@ceid.upatras.gr) Received: from orion.daedalusnetworks.priv (aris.bedc.ondsl.gr [62.103.39.226])j0CHptgo023795 for ; Wed, 12 Jan 2005 19:51:55 +0200 Received: from orion.daedalusnetworks.priv (orion [127.0.0.1]) j0CHpc3X002834 for ; Wed, 12 Jan 2005 19:51:38 +0200 (EET) (envelope-from keramida@ceid.upatras.gr) Received: (from keramida@localhost)j0CHpbBl002833 for freebsd-questions@freebsd.org; Wed, 12 Jan 2005 19:51:37 +0200 (EET) (envelope-from keramida@ceid.upatras.gr) Date: Wed, 12 Jan 2005 19:51:37 +0200 From: Giorgos Keramidas To: freebsd-questions@freebsd.org Message-ID: <20050112175137.GA2734@orion.daedalusnetworks.priv> References: <9094-SnapperMsgD246FC56BE0A255B@68.243.126.247> <20050112014359.GA3722@gothmog.gr> <35de0c30050111210235ea3060@mail.gmail.com> <20050112052901.GA61033@osiris.chen.org.nz> <167683180.20050112072014@wanadoo.fr> <20050112111542.GA1651@orion.daedalusnetworks.priv> <1869737534.20050112184102@wanadoo.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1869737534.20050112184102@wanadoo.fr> Subject: Re: Hyperthreading hurts 5.3? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 12 Jan 2005 17:51:59 -0000 On 2005-01-12 18:41, Anthony Atkielski wrote: > Giorgos Keramidas writes: > > GK> You need to enable SMP too, to allow the FreeBSD kernel to use the > GK> second (hyper-threaded) CPU. > > I found it, in a file called SMP. Why is the SMP option tucked away in > a separate file? [...] The 'separate file' is NOTES. This file is actually the complete reference of options that the kernel supports, so it's not like the SMP option is hidden or something. > I imagine this will give me a bit more horsepower for the buck, > although--with only 0.2% of the machine busy under normal load even with > a single processor--I guess I wasn't exactly processor-bound to begin > with (I'd run out of I/O capacity long before running out of processor). > But why not profit from what's there, eh? Because it's not always a 'profit'. The locking and synchronization overhead is not always negligible. Please, read the rest of the thread too :-) - Giorgos