From owner-freebsd-questions@FreeBSD.ORG Sat Dec 11 22:05:28 2004 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 DCCC816A4CE for ; Sat, 11 Dec 2004 22:05:28 +0000 (GMT) Received: from out2.smtp.messagingengine.com (out2.smtp.messagingengine.com [66.111.4.26]) by mx1.FreeBSD.org (Postfix) with ESMTP id 66E3743D31 for ; Sat, 11 Dec 2004 22:05:28 +0000 (GMT) (envelope-from list-freebsd-2004@morbius.sent.com) Received: from frontend2.messagingengine.com (frontend2.internal [10.202.2.151]) by frontend1.messagingengine.com (Postfix) with ESMTP id BF284C40D02 for ; Sat, 11 Dec 2004 17:05:26 -0500 (EST) X-Sasl-enc: vz8foTOPQGJfh2KdX21ioQ 1102802724 Received: from gumby.localhost (dsl-80-41-36-57.access.uk.tiscali.com [80.41.36.57]) by frontend2.messagingengine.com (Postfix) with ESMTP id E2BBA570147 for ; Sat, 11 Dec 2004 17:05:24 -0500 (EST) From: RW To: freebsd-questions@freebsd.org Date: Sat, 11 Dec 2004 22:05:16 +0000 User-Agent: KMail/1.7.1 References: <36661.194.210.13.66.1102680032.squirrel@194.210.13.66> <41B9F042.4040700@raad.tartu.ee> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200412112205.17410.list-freebsd-2004@morbius.sent.com> Subject: Re: [Fwd: HTT/SMP servers instability on 5.3-STABLE] 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: Sat, 11 Dec 2004 22:05:29 -0000 On Friday 10 December 2004 19:57, Colin J. Raven wrote: > On Dec 10, Toomas Aas launched this into the bitstream: > > Colin J. Raven wrote: > >> On Dec 10, Toomas Aas launched this into the bitstream: > >>> For more than a month now, I've been running a Dual Xeon 2000 system > >>> (IBM eServer xSeries 225) with 5.3-RC2 and later upgraded to > >>> 5.3-RELEASE and I have no problems at all. Hyperthreading is disabled > >>> in BIOS, ACPI is enabled. > >> > >> Excuse me for jumping into this thread but could you elaborate as to why > >> you have Nyperthreading disabled? > > > > I'm afraid I can't give you any good technical reasons. I simply think of > > HTT as Intel marketing blurb, meant to make you feel like you are getting > > two CPUs for the price of one. Well, actually it's still only one CPU. > > I've been running another single Xeon 2.4 box for more than a year. > > Initially, I ran several months with HTT enabled. Then I ran several > > months with HTT disabled. I didn't really notice any performance > > difference. > > Well thanks for sharing those observations. Until I read what you said I > *assumed* that there was a performance difference with HTT > enabled. The specs seem to show that there *is* a theoretical > difference, yet clearly according to your observations there just isn't > any difference of earth shaking proportions. Isn't the point of HTT that a CPU holds several threads from the *same* process. So if your software isn't multithreaded, there's no benifit. UNIX software tends to fork single-threaded process, rather than create new threads, so it benefits from SMP, but not HTT.