On Mon, Feb 14, 2011 at 6:15 PM, Thomas Broda <thomas@xxxxxxxxxxxxx> wrote: > dd'ing /dev/zero to a testfile gives me a throughput of about 400MB/s when > done directly on the hypervisor. If I try this from within a virtual guest, > it's only 19MB/s to 24MB/s if the guest is on the LVM volume (raw device, > not qcow2 or something, no filesystem on top of the LVM). Did you run dd with O_DIRECT? dd if=/dev/zero of=<path-to-device> oflag=direct bs=64k In order to exercise the disk and eliminate page cache effects you need to do this. Also, you are using oldish KVM packages. You could try a modern kernel and KVM userspace. Stefan -- 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
