From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LRc2H-0001mc-4q for qemu-devel@nongnu.org; Mon, 26 Jan 2009 19:42:37 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LRc2F-0001m8-Dl for qemu-devel@nongnu.org; Mon, 26 Jan 2009 19:42:36 -0500 Received: from [199.232.76.173] (port=57154 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LRc2F-0001m2-9J for qemu-devel@nongnu.org; Mon, 26 Jan 2009 19:42:35 -0500 Received: from mail2.shareable.org ([80.68.89.115]:35822) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1LRc2E-00071F-UI for qemu-devel@nongnu.org; Mon, 26 Jan 2009 19:42:35 -0500 Date: Tue, 27 Jan 2009 00:42:32 +0000 From: Jamie Lokier Subject: Re: [Qemu-devel] [PATCH] Enabled building of x86_64 code on Mac OS X Message-ID: <20090127004232.GE9296@shareable.org> References: <1232826287-18542-1-git-send-email-agraf@suse.de> <497DD950.2080908@us.ibm.com> <200901270034.04844.paul@codesourcery.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200901270034.04844.paul@codesourcery.com> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Anthony Liguori Paul Brook wrote: > > Out of curiousity, what are the benefits of using 64-bit apps in OS X? > > My guess is that same as most other x86 targets: The i386 legacy > mode is crippled by lack of registers, modern x86 hardware has a big > fat wide memory bus, and noone's bothered implementing an ILP32 > 64-bit API[1], so 64-bit apps give measurably better overall > performance. Except they use more memory and memory bandwidth (arguably filling nearly half of it with zeros most of the time :-) so worse overall performance in some cases. -- Jamie