Hi, Log from my hypervisor after launch the test VM: 2018-08-01 17:45:58,209 - mom.RPCServer - INFO - ping() 2018-08-01 17:45:58,211 - mom.RPCServer - INFO - getStatistics() 2018-08-01 17:45:58,346 - mom.RPCServer - INFO - ping() 2018-08-01 17:45:58,347 - mom.RPCServer - INFO - getStatistics() 2018-08-01 17:45:58,759 - mom.GuestMonitor.Thread - INFO - GuestMonitor-ovirt-dev-c7-vm1ending 2018-08-01 17:45:58,944 - mom.Controllers.KSM - INFO - Updating KSM configuration: pages_to_scan:0 merge_across_nodes:1 run:0 sleep_millisecs:0 2018-08-01 17:46:13,310 - mom.RPCServer - INFO - ping() 2018-08-01 17:46:13,313 - mom.RPCServer - INFO - getStatistics() 2018-08-01 17:46:13,386 - mom.RPCServer - INFO - ping() 2018-08-01 17:46:13,387 - mom.RPCServer - INFO - getStatistics() 2018-08-01 17:46:28,380 - mom.RPCServer - INFO - ping() 2018-08-01 17:46:28,381 - mom.RPCServer - INFO - getStatistics() 2018-08-01 17:46:28,423 - mom.RPCServer - INFO - ping() 2018-08-01 17:46:28,424 - mom.RPCServer - INFO - getStatistics() 2018-08-01 17:46:28,748 - mom.GuestMonitor.Thread - INFO - GuestMonitor-ovirt-dev-c7-vm1 starting 2018-08-01 17:46:43,402 - mom.RPCServer - INFO - ping() 2018-08-01 17:46:43,403 - mom.RPCServer - INFO - getStatistics() 2018-08-01 17:46:43,459 - mom.RPCServer - INFO - ping() 2018-08-01 17:46:43,460 - mom.RPCServer - INFO - getStatistics() 2018-08-01 17:46:43,772 - mom.Monitor - INFO - ovirt-dev-c7-vm1 is ready 2018-08-01 17:46:58,461 - mom.RPCServer - INFO - ping() 2018-08-01 17:46:58,462 - mom.RPCServer - INFO - getStatistics() 2018-08-01 17:46:58,502 - mom.RPCServer - INFO - ping() 2018-08-01 17:46:58,503 - mom.RPCServer - INFO - getStatistics() After that I lauch my perl program to consume RAM and stop it [root@ovirt-dev-c7-vm1 ~]# free -m total used free shared buff/cache available Mem: 7820 6876 846 2 96 745 Swap: 8063 109 7954 [root@ovirt-dev-c7-vm1 ~]# free -m total used free shared buff/cache available Mem: 7820 188 7535 2 96 7433 Swap: 8063 109 7954 [root@ovirt-dev-c7-vm1 ~]# On hypervisor side, RAM is not released : [root@ovirt-dev1 ~]# free -m total used free shared buff/cache available Mem: 31989 8750 22657 17 581 22816 Swap: 16127 0 16127 [root@ovirt-dev1 ~]# top 22192 vdsm 20 0 681968 24508 5440 S 1,7 0,1 0:01.81 python 22525 qemu 20 0 9126664 8,0g 13664 S 1,7 25,4 0:42.57 qemu-kvm qemu-kvm process still use 8GB RAM instead of ~300MB. An idea ? Thanks !