Re: [Libguestfs] virt-v2v slow when running inside the VM

I eliminated software-bridge( using iperf3 bandwidth/latency on the host and guest was almost the same) and disk write(using qemu-img convert src dest file both on the host and guestvm was comprable) being the issue. Next I profiled both sshd and qemu-img during the conversion phase using bpftools (profile and tcptop) and this is what i see. Time (min) File Size (KB) sshd RX (KB) tcptop qemu-img RX (KB) tcptop profile (flamegraph) 0 - 5 5478400 5612971 5601536 qemu-img-0-5.svg 5 - 10 8365440 (+2887040) 5669043 5656517 qemu-img-5-10.svg 10 - 15 8423296 (+57856) 5722376 5708926 qemu-img-10-15.svg 15 - 20 9472128(+1048832) 5708230 5693710 qemu-img-15-20.svg 20 - 25 9540992(+68864) 5723629 5712002 qemu-img-20-25.svg 25 - 30 9617024(+76032) 5721568 5708794 qemu-img-25-30.svg 30 - 35 11263040(+10646016) 5689537 5678589 qemu-img-30-35.svg 35 – 40 11263040(+0) 5722598 5709954 qemu-img-35-40.svg 40 - 45 13252160(+1989120) 5693774 5682506 qemu-img-40-45.svg 45 - 50 15272576(+12020416) 5698998 5686398 qemu-img-45-50.svg 50 - 55 15272704(128) 985500 983322 qemu-img-50-55.svg Bulk of the write to the "-sda" file completed within 15-20 mins although sshd/qemu-img receives constant stream of data from the nbd-server I'm not sure if this is because of "sparseness" (Not sure if the sparsifying is handled on the nbd-server side or on the receiving side) The flamegraph also show not much of disk write happening after 20 mins. (mostly poll and recv_msg) I am yet todo a similar experiment when running on the "host" to actually compare the behavior. Does this provide any clues? thanks Suresh On Wed, Apr 10, 2019 at 10:30 AM Richard W.M. Jones <rjones(a)redhat.com&gt; wrote: