From owner-freebsd-questions@FreeBSD.ORG Thu Jan 13 00:43:56 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 43B7E16A4CE for ; Thu, 13 Jan 2005 00:43:56 +0000 (GMT) Received: from smtp9.wanadoo.fr (smtp9.wanadoo.fr [193.252.22.22]) by mx1.FreeBSD.org (Postfix) with ESMTP id 00A9543D41 for ; Thu, 13 Jan 2005 00:43:56 +0000 (GMT) (envelope-from atkielski.anthony@wanadoo.fr) Received: from me-wanadoo.net (localhost [127.0.0.1]) by mwinf0912.wanadoo.fr (SMTP Server) with ESMTP id A4E8A1C005E4 for ; Thu, 13 Jan 2005 01:43:54 +0100 (CET) Received: from pix.atkielski.com (ASt-Lambert-111-2-1-3.w81-50.abo.wanadoo.fr [81.50.80.3]) by mwinf0912.wanadoo.fr (SMTP Server) with ESMTP id 859031C005E1 for ; Thu, 13 Jan 2005 01:43:54 +0100 (CET) Date: Thu, 13 Jan 2005 01:43:54 +0100 From: Anthony Atkielski X-Priority: 3 (Normal) Message-ID: <786252184.20050113014354@wanadoo.fr> To: freebsd-questions@freebsd.org In-Reply-To: <41E58E53.7060606@netfence.it> References: <200501121049.j0CAnJQe028309@mp.cs.niu.edu> <828997113.20050112184556@wanadoo.fr> <41E58E53.7060606@netfence.it> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Subject: Re: Hyperthreading hurts 5.3? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: freebsd-questions@freebsd.org List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 13 Jan 2005 00:43:56 -0000 Andrea Venturoli writes: AV> FWIW I tried numerical computations on a P4 with HT enabled: I expected AV> using 2 threads might give *at least slightly* better results, but I AV> could come to the conclusion that with 1, 2 or 4 threads the performance AV> gain (or loss) was exactly zero. Where these computations in which all threads were doing pretty much the same thing? And was it floating-point? (Doesn't the processor have just one FPU, or something like that?) AV> BTW, an old AMD 2000 XP+ would in any case almost outperform a P4 3GHz, AV> but that's another story. An AMD processor will also melt or catch fire if the CPU fan fails, whereas an Intel processor won't. I found this out the hard way, and so henceforth I'll be installing Intel processors. The cost savings one gets from buying AMD isn't enough to pay for a new motherboard or PC. AV> Obviously your use (as a server) is very different, and probably the AV> one test I have done can't expect to achieve 100% coverage even in AV> this field... but, anyway, just my 2 cents... I have no easy way to measure the performance on my system, so I'm mostly just speculating--but it seems logical. -- Anthony