Set limits for the maximum and minimum amount of system memory to allocate to the host operating system (domain 0). For instructions, see Managing Domain 0 Memory .

Disable powersave functionality on the host and all guest operating systems. On the host computer and other Linux computers, you can use the chkconfig powersaved off command.

Close Virtual Machine Manager if you are not actively using it and restart it when needed. Closing Virtual Machine Manager does not affect the state of virtual machines.

If left running, Virtual Machine Manager incrementally consumes domain 0 memory. With diminishing system memory in domain 0, virtual machine performance slows and then out-of-memory error messages start to appear in domain 0 and all virtual machines. Closing Virtual Machine Machine manager releases the additional memory it consumed.