Concerns has been raised about the benefits and drawbacks of migration compression feature which was optional in 3.6 and is now part of the default profile in 4.0. The impact of higher CPU and memory usage has not been fully understood and some of the initial testing was flawed We may want to do further testing but until that's done we should consider disabling it in the default case
can you give it a try and compare the impact please?
Checked with 4.0.4.4-0.1.el7ev Set compression off in default policy. Migrate 1 GB and 10 GB VM, The migrate took 17 sec for 1GB VM and 23 sec for 10GB VM which is longer then with compression about 17%-15% more. No errors found in host(vdsm,libvirt)/engine logs
Verify with: Engine: 4.0.5-0.1.el7ev Host: OS Version:RHEL - 7.2 - 9.el7_2.1 Kernel Version:3.10.0 - 327.35.1.el7.x86_64 KVM Version:2.3.0 - 31.el7_2.22 LIBVIRT Version:libvirt-1.2.17-13.el7_2.6 VDSM Version:vdsm-4.18.5.1-1.el7ev SPICE Version:0.12.4 - 15.el7_2.2 Steps: 1. Create VM with 1 GB and VM with 1 GB memory 2. Migrate VMs 3. Check logs on engine and hosts Results: Migrate PASS, No errors found on logs