From owner-freebsd-hardware@FreeBSD.ORG Wed Mar 3 20:35:51 2004 Return-Path: Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C312516A4CE for ; Wed, 3 Mar 2004 20:35:51 -0800 (PST) Received: from cobra.acceleratedweb.net (cobra-gw.acceleratedweb.net [207.99.79.37]) by mx1.FreeBSD.org (Postfix) with SMTP id 3A51E43D1D for ; Wed, 3 Mar 2004 20:35:51 -0800 (PST) (envelope-from simon@optinet.com) Received: (qmail 37408 invoked by uid 110); 4 Mar 2004 04:35:50 -0000 Received: from ool-18baaf5c.dyn.optonline.net (HELO win2kpc1) (24.186.175.92) by cobra.acceleratedweb.net with SMTP; 4 Mar 2004 04:35:50 -0000 From: "Simon" To: "Erich Dollansky" Date: Wed, 03 Mar 2004 23:36:05 -0500 Priority: Normal X-Mailer: PMMail 2000 Professional (2.20.2661) For Windows 2000 (5.0.2195;4) In-Reply-To: <4046AEE0.4010201@pacific.net.sg> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Message-Id: <20040304043551.3A51E43D1D@mx1.FreeBSD.org> cc: "hardware@freebsd.org" Subject: Re: Xeon w/ L3 1MB cache vs Xeon w/o L3 cache X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 04 Mar 2004 04:35:51 -0000 Thanks, I read that under higher loads, the L3 cache becomes quite useful, too. But, what is considered high-load? what determines if L3 cache is used or not? is it app to the app to use it? or up to the kernel? or the CPU itself? or a combination? We run a lot of services on our servers and I would say they are heavy loaded, but I could be mistaking, I mean, they do a lot of processing but not exactly crawling, they are still fast. Thanks, Simon On Thu, 04 Mar 2004 12:21:52 +0800, Erich Dollansky wrote: >Hi, > >Simon wrote: > >> Has anyone done any comparison to see if extra L3 cache on Xeon CPUs >> provides any benefit to FreeBSD's kernel/core services and various user >> services' (http/email/ftp/databases) performance? I read that L3 can make >> things slower instead of faster in cases where L3 is not utilized and the CPU >> is forced to access it anyway (when L1/L2 don't hold the data it wants), >> because it exists. Would anyone with personal experience with Xeon CPUs >> with and without L3 cache comment on the impact of L3 cache. Any links >> to any related articles would be appreciated, as well. >> >I only have experience with other CPUs with L3 cache. L3 keeps >them faster under high load conditions. It made a small negative >impact under low load conditions because their L3 cache was much >slower than their L1 and L2 caches. > >If you have the high load it is worth the high price they cost. > >I do not have any links for this. The work was done some time ago >in a typical ISP environment. The tests included only FTP and >database. > >Erich >