Erik Jacobson wrote:
We have been trying to test qemu-kvm virtual machines under an IO load. The IO load is quite simple: A timed build of the linux kernel and modules. I have found that virtual machines take more than twice as long to do this build as the host. It doesn't seem to matter if I use virtio or not, Using the same device and same filesystem, the host is more than twice as fast. We're hoping that we can get some advice on how to address this issue. If there are any options I should add for our testing, we'd appreciate it. I'm also game to try development bits to see if they make a difference. If it turns out "that is just the way it is right now", we'd like to know that too. For these tests, I used Fedora 11 as the virtualization server. I did this because it has recent bits. I experimented with SLES11 and Fedora11 guests. In general, I used virt-manager to do the setup and launching. So the qemu-kvm command lines are based on that (and this explains why they are a bit long). I then modified the qemu-kvm command line to perform other variations of the test. Example command lines can be found at the end of this message. I performed tests on two different systems to be sure it isn't related to specific hardware.
What is the host cpu type? On pre-Nehalem/Barcelona processors kvm has poor scalability in mmu intensive workloads like kernel builds.
-- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
