From owner-freebsd-questions@FreeBSD.ORG Wed Jan 12 02:31:28 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 79DA116A4CE for ; Wed, 12 Jan 2005 02:31:28 +0000 (GMT) Received: from pi.codefab.com (pi.codefab.com [199.103.21.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id C602E43D3F for ; Wed, 12 Jan 2005 02:31:27 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from [192.168.1.3] (pool-68-160-208-232.ny325.east.verizon.net [68.160.208.232]) by pi.codefab.com (8.12.11/8.12.11) with ESMTP id j0C2VMlh033997 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 11 Jan 2005 21:31:24 -0500 (EST) Message-ID: <41E48BDE.7010301@mac.com> Date: Tue, 11 Jan 2005 21:30:54 -0500 From: Chuck Swiger Organization: The Courts of Chaos User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.5) Gecko/20041217 X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Timothy J. Luoma" References: <9094-SnapperMsgD246FC56BE0A255B@68.243.126.247> In-Reply-To: <9094-SnapperMsgD246FC56BE0A255B@68.243.126.247> X-Enigmail-Version: 0.90.0.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=1.8 required=5.5 tests=AWL,RCVD_IN_NJABL_DUL, RCVD_IN_SORBS_DUL autolearn=disabled version=3.0.1 X-Spam-Level: * X-Spam-Checker-Version: SpamAssassin 3.0.1 (2004-10-22) on pi.codefab.com cc: freebsd-questions@freebsd.org 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 02:31:28 -0000 Timothy J. Luoma wrote: > summary: should I disable hypertheading in the BIOS when running 5.3? It would certainly be worth trying this and seeing whether running as a purely single-proc system performs better for you. It's not exactly as if HyperThreading evolved out of a sensible plan like "let's design a multi-core CPU intended for parallel execution, or something like a m56k DSP with VLIW", the situation is more like "Intel created the P4 such a monsterously long pipeline that breaks x86 instructions into tiny u-ops which require a lot of functional units to be available, only the CPU still can't schedule things to use all of the available units much of the time, anyway, so hey, maybe we could run another processing thread on 'em and hope the additional work it can do outweighs the additional CPU resource contention and the additional overhead of doing SMP..." [ I have a non-HT P4 (a 2.4MHz@400FSB Northwood) around, but I doubt I'd turn HT on with it even if it could. I'd rather use an AMD-64, or a G5, or even a recent P3 (Tualatin/Pentium-M) than another hyperthermal P4 spaceheater. ] Bah, I'm rambling, time to stop... :-) -- -Chuck