From owner-freebsd-current@FreeBSD.ORG Thu May 7 09:26:50 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 BADF61065673 for ; Thu, 7 May 2009 09:26:50 +0000 (UTC) (envelope-from barney_cordoba@yahoo.com) Received: from web63907.mail.re1.yahoo.com (web63907.mail.re1.yahoo.com [69.147.97.122]) by mx1.freebsd.org (Postfix) with SMTP id 5D1078FC15 for ; Thu, 7 May 2009 09:26:50 +0000 (UTC) (envelope-from barney_cordoba@yahoo.com) Received: (qmail 2400 invoked by uid 60001); 7 May 2009 09:26:49 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1241688409; bh=wQuGxgnvYVXkV1a40AOY/gqjiJ5vvKX4M7nzx7cMRCo=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Reply-To:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type; b=nf6ww8tCMRerBYSAGA9OexKPw+FJ4cKdhq7pYuS4iDMNCh8YDCOt/EWfb0Fx9pQE2iXPzqW++7qL4YHaZiSEr0TcyhWb6fNZ69WUCgWxLg6u3DXcPdxtyL0ldfmrrsjzF5aSypplZ8qCtD2GZuyNrDO1MHMqByC+77NBzdjArQU= DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Reply-To:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type; b=QSDLr4BPeBTiMpHkQLmnul+DUE39hk784Cj4PQIHNQ4alL4b1VzN5/WJaAJjP5C/hk3noDatXRFst+745IFgJLbfogsjOhCb1PhsLURkcHQXOFpvAPDvaW4bATbJVBBnKgPawr1rwgvDRe5rgPU9saq2SUlo9ywsSNVawWusV5s=; Message-ID: <758865.1091.qm@web63907.mail.re1.yahoo.com> X-YMail-OSG: pgkfytwVM1kfx2H6XVCa1wPSegL_P5a4hL9Hwb8XT_EgN8lQ.K8Ig6cLzvEoKLPZo.rso.HLNeLETvpv7.4M6.W.E9txYjWVOBfqjBr44vZmwTnPN42mnd2_CntWjG8fpmbEUKto.sF1Z45STkWcSgaDGQBJ9n_AGRtessHAanh58ohFtEvZGtlo_IadHOcrvH6KCJAegYx90zVwkWm4kexGtNKgethJpxBc8kbR6j2ydq1XShowzqufiPs5aVP9SlxdlRt.AMBErcssJBdlTrD2xS4- Received: from [98.242.223.106] by web63907.mail.re1.yahoo.com via HTTP; Thu, 07 May 2009 02:26:49 PDT X-Mailer: YahooMailWebService/0.7.289.1 Date: Thu, 7 May 2009 02:26:49 -0700 (PDT) From: Barney Cordoba To: pluknet In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Current@freebsd.org" Subject: Re: Hypertherading X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: barney_cordoba@yahoo.com 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 09:26:51 -0000 --- 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? > > > > 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