Test 1: Created a new VM and kept it Idle for 60+ hours, then ran Unix benchmark test against it. (NO Live-migration/migration)
Result 1: The performance was NOT affected and the result was the same as a fresh VM.
Test 2: Created a new VM, and perform a "virsh save <domain> <file>" followed by a "virsh restore <file>" on the SAME hypervisor. Then run unix benchmark against it.
Result 2: The VM is AFFECTED (cost to perform system calls degraded by ~21% )
Test 3: Rebooted the affected VM from test (2) and re-ran unix-benchmark tests against it.
Result 3: Performance is back to normal and is identical to a newly created and non-migrated/not-saved VM.
Thus, it seems the problem is also exposed by "saving" the running precise domain (memory pages) to state file followed by a "restore" even on the same hypervisor and not necessarily live-migration to a different host.
Few updates from a few tests we ran:
Setup: 0ubuntu14. 7
hypervisor ==> Ubuntu 12.04.2 LTS
libvirt ===> 0.9.8-2ubuntu17.7
qemu-kvm ===> 1.0+noroms-
storage: NFS exports
Guest VM OS: Ubuntu 12.04.1 LTS
Test 1: Created a new VM and kept it Idle for 60+ hours, then ran Unix benchmark test against it. (NO Live-migration/ migration)
Result 1: The performance was NOT affected and the result was the same as a fresh VM.
Test 2: Created a new VM, and perform a "virsh save <domain> <file>" followed by a "virsh restore <file>" on the SAME hypervisor. Then run unix benchmark against it.
Result 2: The VM is AFFECTED (cost to perform system calls degraded by ~21% )
Test 3: Rebooted the affected VM from test (2) and re-ran unix-benchmark tests against it. not-saved VM.
Result 3: Performance is back to normal and is identical to a newly created and non-migrated/
Thus, it seems the problem is also exposed by "saving" the running precise domain (memory pages) to state file followed by a "restore" even on the same hypervisor and not necessarily live-migration to a different host.