15.20. Изменение выделенного объема памяти

You can use virsh to modify a domain's memory allocation:
virsh setmem [domain-id | domain-name]  [count]
You must specify the [count] in kilobytes. Note that the new count cannot exceed the amount you specified when you created the Virtual Machine. Values lower than 64 MB probably won't work. You can adjust the Virtual Machine memory as necessary.