From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1KSwrU-0000XT-VP for qemu-devel@nongnu.org; Tue, 12 Aug 2008 12:36:45 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1KSwrT-0000Vg-Ry for qemu-devel@nongnu.org; Tue, 12 Aug 2008 12:36:44 -0400 Received: from [199.232.76.173] (port=37626 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1KSwrT-0000VY-Na for qemu-devel@nongnu.org; Tue, 12 Aug 2008 12:36:43 -0400 Received: from yw-out-1718.google.com ([74.125.46.158]:56882) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1KSwrT-0003wQ-Dy for qemu-devel@nongnu.org; Tue, 12 Aug 2008 12:36:43 -0400 Received: by yw-out-1718.google.com with SMTP id 6so1053903ywa.82 for ; Tue, 12 Aug 2008 09:36:41 -0700 (PDT) Message-ID: <48A1BBF8.30407@quinthar.com> Date: Tue, 12 Aug 2008 09:36:08 -0700 From: David Barrett MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] AMD 100% CPU bug; patch available? 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 Can anybody confirm that qemu works on an AMD processor with a Linux host and Linux guest (ideally Ubuntu 8.04 in both cases) without using 100% CPU? (qemu process on the host uses 100% CPU despite all processes on the guest being idle.) Or is there a known bug that qemu with a Ubuntu guest always uses 100% CPU on AMD Ubuntu hosts? If so, is there a patch or workaround for it? I don't know this for certain, but it's the only pattern I can see: I've run qemu on a bunch of laptops and servers over the past 12 months -- often with the exact same image and exact same commands -- and some hosts see the guest VM use limited CPU, and others a solid 100%. This seems to be the case whether or not -kernel-kqemu is used. At first I thought it was an Ubuntu/Fedora Core issue, as I was running Ubuntu on laptops and FC4 on servers (and I only saw this problem on servers). But I just got a new Ubuntu server and the problem remains. Now I realize there's another commonality: my servers have been AMD-based, whereas laptops were Intel based. With this theory I looked through the user forum and saw a strong correlation between reports of 100% CPU and AMD processors. Is this old news or a debunked theory? Is there some tool like CPUIdle I should be running? Any suggestions for how to start debugging the issue? Thanks! -david