24.8 Configuring the Memory Assigned to a Guest OS
To configure the memory assigned to a guest OS, use the setmem option of the virsh command. For example, the following command reduces the memory allocated to a guest system to 256Mb:
# virsh setmem guestName 256
Note that acceptable memory settings must fall within the memory available to the current Domain. This may be increased using the setmaxmem option.