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) I don't see any of the qemu process running. Initial overlay setup was pretty quick and rest of the time was spent in qemu-img convert operation
Suresh On Wed, Apr 10, 2019 at 6:22 AM Richard W.M. Jones <[email protected]> wrote: > 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 >
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