From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LRk8t-0001dp-Gw for qemu-devel@nongnu.org; Tue, 27 Jan 2009 04:21:59 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LRk8t-0001dd-25 for qemu-devel@nongnu.org; Tue, 27 Jan 2009 04:21:59 -0500 Received: from [199.232.76.173] (port=37570 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LRk8s-0001da-SH for qemu-devel@nongnu.org; Tue, 27 Jan 2009 04:21:58 -0500 Received: from ns.suse.de ([195.135.220.2]:52110 helo=mx1.suse.de) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1LRk8s-0006v9-Fd for qemu-devel@nongnu.org; Tue, 27 Jan 2009 04:21:58 -0500 Message-ID: <497ED233.7010504@suse.de> Date: Tue, 27 Jan 2009 10:21:55 +0100 From: Alexander Graf MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH] Enabled building of x86_64 code on Mac OS X References: <1232826287-18542-1-git-send-email-agraf@suse.de> <200901270034.04844.paul@codesourcery.com> <20090127004232.GE9296@shareable.org> <200901270059.21958.paul@codesourcery.com> <497E61DE.2080802@us.ibm.com> In-Reply-To: <497E61DE.2080802@us.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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: Paul Brook Anthony Liguori wrote: > Paul Brook wrote: >> I did say overall performance. >> My experience with AMD hardware is that you generally get ~10% >> overall improvement from LP64. Intel hardware (particularly the early >> 64-bit cores) less so, but it's generally still a win. >> >> I guess ILP32 long mode would probably increase that further, and >> avoid the odd regressions. It's an awful lot of work to implement >> though, especially on a target that isn't used to having lots of >> incompatible variants. >> > > I expected a performance boost. Since OS X only runs on Intel CPUs, I > don't think it's dramatically worth it to get a few percent CPU > improvement. The reason I asked is that if we decided to drop Cocoa > in favor of SDL, it would prevent the use of 64-bit. The extra registers should speed up things quite a bit. While that's not too much of a problem when emulating x86, which has few registers anyway, emulating a ppc or x86_64 target should be faster on an x86_64 host. I haven't done measurements though. As for the plus in code size on x86_64 - that doesn't really apply to tcg, as that still generates 32-bit code when only 32-bit code is necessary, which still looks the same on x86_64. Plus it does simplify 64-bit operations. I would be very surprised if the improvement of emulating x86_64 on x86 vs. x86_64 is only ~10%. Alex