From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1KSxWt-0000C6-MD for qemu-devel@nongnu.org; Tue, 12 Aug 2008 13:19:31 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1KSxWr-0000Bu-2e for qemu-devel@nongnu.org; Tue, 12 Aug 2008 13:19:30 -0400 Received: from [199.232.76.173] (port=38149 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1KSxWq-0000Br-Sd for qemu-devel@nongnu.org; Tue, 12 Aug 2008 13:19:28 -0400 Received: from hobi.com ([130.94.185.247]:4604) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1KSxWq-0004dO-DW for qemu-devel@nongnu.org; Tue, 12 Aug 2008 13:19:28 -0400 Received: from unknown (HELO ricklap) ([68.23.60.237]) (envelope-sender ) by 130.94.185.247 (qmail-ldap-1.03) with SMTP for ; 12 Aug 2008 17:19:26 -0000 From: Rick Vernam Subject: Re: [Qemu-devel] AMD 100% CPU bug; patch available? Date: Tue, 12 Aug 2008 12:19:24 -0500 References: <48A1BBF8.30407@quinthar.com> In-Reply-To: <48A1BBF8.30407@quinthar.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200808121219.24859.rickv@hobi.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 I'm not so sure there is such a bug - I've been running qemu on AMD 3700 laptop for years w/o that, or much of any other issue (except once upon a time an ACPI issue w/ windows guest causing host cpu to peg 100%). I run gentoo host + various windows/linux guests. points of interest may (or may not) be details such as host kernel configuration? qemu version? qemu options used? built yourself or pre-packaged? I don't claim to be able to help you solve the problem, but there's not much here to work with... On Tuesday 12 August 2008 11:36:08 am David Barrett wrote: > 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