On Tue, Apr 09, 2019 at 06:37:46PM -0700, Sureshkumar Kaliannan wrote: > Hi, > > I'm trying to create a clone of a physical Window VM using p2v. > > My goal is to create a cloning tools VM that has libguestfs tools installed > and acts as the convertor. > VM conversion works just fine but the conversion rate is significantly > slow(1/3) when running inside the VM compared to when the v2v is run on the > same bare-metal host. > > On the host: > ./virt-p2v-20190405-w1f4efxy/virt-v2v-conversion-log.txt:virtual copying > rate: 615.9 M bits/sec > ./virt-p2v-20190405-w1f4efxy/virt-v2v-conversion-log.txt:real copying rate: > 181.8 M bits/sec > > >From the Guest VM (On the same bare-metal host) > virt-p2v-20190405-95azj89j/virt-v2v-conversion-log.txt:virtual copying > rate: 185.1 M bits/sec > virt-p2v-20190405-95azj89j/virt-v2v-conversion-log.txt:real copying rate: > 62.7 M bits/sec > > I understand there are several factors come into play but i tried to make > the VM comparable by making sure enough CPU / memory is given to the VM. > Also the I played by adjusting the disk cache modes for the VM(cache=none, > cache=unsafe). When the conversion happens there is not much load and > there are no other VMs on this machine. > > I ruled out the disk being the bootleneck because when i do "virt-v2v -i > disk" conversion the VM is only slightly off. > For the same disk image, > virt-v2v when running in the host took '75 sec' whereas in the VM it took > '100 sec' > > How to go about debugging this performance issue? Any pointers would be > helpful I think this is just KVM vs TCG? You could try enabling nested KVM to see if that makes things faster, but it very much depends on your host CPU. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org

On Wed, Apr 10, 2019 at 10:15:43AM -0700, Sureshkumar Kaliannan wrote: > thanks Richard, > > The experiment was indeed done with nested VM enabled. I am not sure about > the internals, but i thought once overlay is setup the 2 main processes are > sshd and qemu-img convert (reading data from sshd and doing the conversion) Yes this should be true. I wouldn't expect copying to be slower. So initial guess probably wrong. I wonder if there are some extra steps such as a slow software bridge or openvswitch on the host? > I don't see any of the qemu process running. As per http://libguestfs.org/virt-p2v.1.html#how-virt-p2v-works you should see qemu-nbd running on the physical server, and qemu-img running on the conversion server during the copying phase. > Initial overlay setup was pretty quick and rest of the time was spent in > qemu-img convert operation Indeed qemu should exit before copying starts. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/