From owner-freebsd-current@FreeBSD.ORG Wed Jun 6 10:47:58 2007 Return-Path: X-Original-To: freebsd-current@FreeBSD.ORG Delivered-To: freebsd-current@FreeBSD.ORG Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 5231F16A400 for ; Wed, 6 Jun 2007 10:47:58 +0000 (UTC) (envelope-from des@des.no) Received: from tim.des.no (tim.des.no [194.63.250.121]) by mx1.freebsd.org (Postfix) with ESMTP id 3F86613C455 for ; Wed, 6 Jun 2007 10:47:56 +0000 (UTC) (envelope-from des@des.no) Received: from tim.des.no (localhost [127.0.0.1]) by spam.des.no (Postfix) with ESMTP id 7621F20A5; Wed, 6 Jun 2007 12:47:52 +0200 (CEST) X-Spam-Tests: AWL X-Spam-Learn: disabled X-Spam-Score: 0.0/3.0 X-Spam-Checker-Version: SpamAssassin 3.2.0 (2007-05-01) on tim.des.no Received: from dwp.des.no (des.no [80.203.243.180]) by smtp.des.no (Postfix) with ESMTP id EE1D420A4; Wed, 6 Jun 2007 12:47:51 +0200 (CEST) Received: by dwp.des.no (Postfix, from userid 1001) id 774D256F5; Wed, 6 Jun 2007 12:47:59 +0200 (CEST) From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= To: freebsd-current@FreeBSD.ORG References: <200706051316.l55DGSU0052272@lurza.secnetix.de> Date: Wed, 06 Jun 2007 12:47:59 +0200 In-Reply-To: <200706051316.l55DGSU0052272@lurza.secnetix.de> (Oliver Fromme's message of "Tue\, 5 Jun 2007 15\:16\:28 +0200 \(CEST\)") Message-ID: <86ps49l5pc.fsf@dwp.des.no> User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.3 (berkeley-unix) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Cc: jroberson@chesapeake.net, almarrie@gmail.com Subject: Re: Intel C2D COREs not used equally in FreeBSD 7.0-CURRENT i386 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 Jun 2007 10:47:58 -0000 Oliver Fromme writes: > It's a common mistake to assume that amd64 only makes sense > if you have >=3D 4GB RAM. There are several reasons why it > might be useful to switch from i386 to amd64: > > - Most programs (though not all) will run faster, because > in amd64 mode there are twice as many general-purpose > registers, giving compilers much better opportunities > for optimizations and caching of values, and reducing > slow memory accesses. "twice as many" is an understatement. AMD64 has 16 GPRs vs i386's 8 if you consider BP, SI, DI and SP as GPRs (as the AMD and Intel literature does); in practical terms the score is 12 to 4. > - Some applications might benefit from a larger virtual > address space > 4 GB. (Note that this is not related > to the amount of physical RAM!) For instance, Varnish maps its entire storage into memory, and will benefit greatly from the increased address space. > In practice there's (almost) only one reason not to run > FreeBSD/amd64 on amd64-capable hardware: If you depend > on a certain piece of software which is known not to run > correctly in 64bit mode. Fortunately those are not many. The only one I can think of (for a desktop) is the Flash plugin. DES --=20 Dag-Erling Sm=C3=B8rgrav - des@des.no