From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: QEMU vs KVM Date: Wed, 12 Sep 2007 12:04:33 +0300 Message-ID: <46E7ABA1.5060107@qumranet.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel To: gerryw-dHy0zPTSVEVBDgjK7y7TUQ@public.gmane.org Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org gerryw-dHy0zPTSVEVBDgjK7y7TUQ@public.gmane.org wrote: > > Hello All, > > I am a bit unclear about the differences between QEMU and KVM. If I > understand correctly, QEMU can run in a mode on an x86 where it > executes user space code directly on the cpu without emulation. This > seems to be very similar to what KVM is doing with the exception of > using the virtualization capability of the cpu. I would think there > would be very little difference in performance between the two in this > case. Please forgive my ignorance, because I don't know that much > about the new VT cpus yet. What is the actual difference / objective > of the KVM project? You're describing kqemu, not qemu. Qemu is an emulator; it can emualte a large number of guests on a large number of hosts, albeit at fairly slow speeds. kqemu is a "qemu accelerator" which can be used to speed up qemu emulation if the guest and host are the same. kvm is a hardware virtualization system that is part of the Linux kernel. While at present the only serious user is a modified qemu, it is not tied to qemu. It is faster than either qemu of kqemu. The downside is that it requires hardware virtualization extensions for fully virtualized guests. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/