This chapter covers advanced administration tools for fine tuning and controlling system resources as they are made available to guest virtual machines.
8.1. Control Groups (cgroups)
Red Hat Enterprise Linux 6 provides a new kernel feature: control groups, which are often referred to as cgroups. Cgroups allow you to allocate resources such as CPU time, system memory, network bandwidth, or a combination of these resources among user-defined groups of tasks (processes) running on a system. You can monitor the cgroups you configure, deny cgroups access to certain resources, and even reconfigure your cgroups dynamically on a running system.
The cgroup functionality is fully supported by libvirt. By default, libvirt puts each guest into a separate control group for various controllers (such as memory, cpu, blkio, device).