8.3. Steal Time Accounting

Steal time is the amount of CPU time needed by a guest virtual machine that is not provided by the host. Steal time occurs when the host allocates these resources elsewhere: for example, to another guest.
Steal time is reported in the CPU time fields in /proc/stat. It is automatically reported by utilities such as top and vmstat. It is displayed as "%st", or in the "st" column. Note that it cannot be switched off.
Large amounts of steal time indicate CPU contention, which can reduce guest performance. To relieve CPU contention, increase the guest's CPU priority or CPU quota, or run fewer guests on the host.