From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:48209) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SWmQq-00028M-IK for qemu-devel@nongnu.org; Tue, 22 May 2012 06:35:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SWmQj-0003Wm-F8 for qemu-devel@nongnu.org; Tue, 22 May 2012 06:35:12 -0400 Received: from david.siemens.de ([192.35.17.14]:32023) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SWmQj-0003Pk-4m for qemu-devel@nongnu.org; Tue, 22 May 2012 06:35:05 -0400 Message-ID: <4FBB6BD1.9080003@siemens.com> Date: Tue, 22 May 2012 07:34:57 -0300 From: Jan Kiszka MIME-Version: 1.0 References: <4FBA735D.4010701@rdsoftware.de> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Current differences between qemu --enable-kvm and qemu-kvm? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Avi Kivity , Erik Rull , "qemu-devel@nongnu.org" , Marcelo Tosatti On 2012-05-22 07:04, Stefan Hajnoczi wrote: > On Mon, May 21, 2012 at 5:54 PM, Erik Rull wrote: >> is there a summary existing that shows up the rough or actual differences >> between qemu --enable-kvm and qemu-kvm? I tested both versions with the same >> compile and start options, the CPU performance results are identical, only >> the bootup time of my guest system with qemu-kvm seemed to be a bit faster >> (not measured, it just feeled so). Current upstream does not enable the in-kernel irqchip of KVM by default. This should explain the difference in boot-up times. Try "-machine accel=kvm,kernel_irqchip=on". But the default will be on, just like in qemu-kvm, once [1] is merged. > > For production KVM instances I think it still makes sense to use > qemu-kvm packages from your distro or qemu-kvm upstream source. > > Jan Kiszka has reduced the delta between qemu.git and qemu-kvm.git to > the point where I think the list of differences is rather small - > maybe PCI passthrough stuff, irqfd for vhost-net (which is now also > being upstreamed into qemu.git), and a few other things I don't know > of. Right, the list of differences is dramatically shrinking. As stated in [2], soon only PCI passthrough and legacy interface dependencies on qemu-kvm will be the remaining reasons to use it. If we are lucky, PCI passthrough will also make it into upstream for QEMU 1.2, we are working on this. > > For development most patches should be against qemu.git unless they > have a dependency on qemu-kvm.git code. Yes, unless you are working on the upstream merge itself, there is practically no reason anymore to develop against qemu-kvm directly. Jan [1] http://thread.gmane.org/gmane.comp.emulators.kvm.devel/91171 [2] http://thread.gmane.org/gmane.comp.emulators.kvm.devel/91026 -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux