From owner-freebsd-current@FreeBSD.ORG Thu May 7 09:31:12 2009 Return-Path: Delivered-To: Current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A3C83106566B for ; Thu, 7 May 2009 09:31:12 +0000 (UTC) (envelope-from olivier@gid0.org) Received: from yx-out-2324.google.com (yx-out-2324.google.com [74.125.44.30]) by mx1.freebsd.org (Postfix) with ESMTP id 6C1FA8FC12 for ; Thu, 7 May 2009 09:31:12 +0000 (UTC) (envelope-from olivier@gid0.org) Received: by yx-out-2324.google.com with SMTP id 8so388885yxb.13 for ; Thu, 07 May 2009 02:31:12 -0700 (PDT) MIME-Version: 1.0 Received: by 10.90.97.18 with SMTP id u18mr406971agb.33.1241688671645; Thu, 07 May 2009 02:31:11 -0700 (PDT) In-Reply-To: <758865.1091.qm@web63907.mail.re1.yahoo.com> References: <758865.1091.qm@web63907.mail.re1.yahoo.com> Date: Thu, 7 May 2009 11:31:11 +0200 Message-ID: <367b2c980905070231r37a94eack399f5afed742247f@mail.gmail.com> From: Olivier SMEDTS To: barney_cordoba@yahoo.com Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: pluknet , "Current@freebsd.org" Subject: Re: Hypertherading 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: Thu, 07 May 2009 09:31:12 -0000 2009/5/7 Barney Cordoba : > > > > > --- On Wed, 5/6/09, pluknet wrote: > >> From: pluknet >> Subject: Re: Hypertherading >> To: "Barney Cordoba" >> Cc: "Current@freebsd.org" >> Date: Wednesday, May 6, 2009, 10:55 PM >> 2009/5/7 Barney Cordoba : >> > >> > 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? There can be some benefit if the scheduler is aware of the topoly of CPUs and Hyperthreading (shared cache). I don't know how SCHED_ULE handles this on -CURRENT. If it doesn't see any difference between CPU cores and "HT" cores, you should disable HT in BIOS. >> > >> >> 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 >> > > I wouldn't call varying the number of jobs a very good test > of hyperthreading. I'd want to see the exact same test with > hyperthreading enabled and disabled. Its pretty naive > to assume that running 16 jobs causes them to all be run on > a different cpu. > > Barney > > > > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" > -- Olivier Smedts _ ASCII ribbon campaign ( ) e-mail: olivier@gid0.org - against HTML email & vCards X www: http://www.gid0.org - against proprietary attachments / \ "Il y a seulement 10 sortes de gens dans le monde : ceux qui comprennent le binaire, et ceux qui ne le comprennent pas."