MOM is a policy-driven tool that can be used to manage overcommitment on KVM hosts. Using libvirt, MOM keeps track of active virtual machines on a host. At a regular collection interval, data is gathered about the host and guests. Data can come from multiple sources (eg. the /proc interface, libvirt API calls, a client program connected to a guest, etc). Once collected, the data is organized for use by the policy evaluation engine. When started, MOM accepts a user-supplied overcommitment policy. This policy is regularly evaluated using the latest collected data. In response to certain conditions, the policy may trigger reconfiguration of the system’s overcommitment mechanisms. Currently MOM supports control of memory ballooning and KSM but the architecture is designed to accommodate new mechanisms such as cgroups.