From owner-freebsd-stable@FreeBSD.ORG Sun Nov 4 22:39:29 2007 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 4F4ED16A419 for ; Sun, 4 Nov 2007 22:39:29 +0000 (UTC) (envelope-from rb@gid.co.uk) Received: from gidgate.gid.co.uk (gid.co.uk [194.32.164.225]) by mx1.freebsd.org (Postfix) with ESMTP id DCFC313C4A3 for ; Sun, 4 Nov 2007 22:39:28 +0000 (UTC) (envelope-from rb@gid.co.uk) Received: from [194.32.164.30] (host-83-146-60-88.bulldogdsl.com [83.146.60.88]) by gidgate.gid.co.uk (8.13.8/8.13.8) with ESMTP id lA4MJ0KZ078915; Sun, 4 Nov 2007 22:19:00 GMT (envelope-from rb@gid.co.uk) In-Reply-To: References: Mime-Version: 1.0 (Apple Message framework v752.3) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: Content-Transfer-Encoding: 7bit From: Bob Bishop Date: Sun, 4 Nov 2007 22:19:14 +0000 To: Pete French X-Mailer: Apple Mail (2.752.3) Cc: freebsd-stable@freebsd.org Subject: Re: Best way to use more that 4 gigs of memory ? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 04 Nov 2007 22:39:29 -0000 Hi, On 4 Nov 2007, at 21:11, Pete French wrote: > I have been doing some experiments with runnign 32 bit processed on > and amd64 kernel over the last couple of days and am wondering what > the general feel is for the best way to use over 4 gigs of memory. > As far > as I can see I have 3 options: > > 1) amd64 kernel + 64 bit processes > 2) amd64 kernel + 32 bit processes > 3) i386 kernel with PAE and 32 bit processes > > I was initially thinking that option 1 was the best, but > benchmarking it > the programs take 3 times longer to run that option 2! This > astounds me > and I intend to investigate why, but given it is rue then that > rules it out > as a viable solution for deploying stuff. I had similar results, I surmise (without evidence) it's to do with cache usage. > Which leaves either 32 bit processes on a 64 bit kernel or > alternatively > running under PAE on a 32 bit kerenel. I don't know a lot about PAE > and > was wondering if anyone had any advice either way as to which > wouldbe the most > stable and/or best performing. If your workload is CPU-intensive it probably doesn't matter; if it isn't, I'd do some more experiments. > cheers, > > -pcf. -- Bob Bishop +44 (0)118 940 1243 rb@gid.co.uk fax +44 (0)118 940 1295