Managing CPU Share

The Parallels Server Bare Metal CPU resource control utilities allow you to guarantee any Container the amount of CPU time this Container receives. The Container can consume more than the guaranteed value if there are no other Containers competing for the CPU and the cpulimit parameter is not defined.

Note: The CPU time shares and limits are calculated on the basis of a one-second period. Thus, for example, if a Container is not allowed to receive more than 50% of the CPU time, it will be able to receive no more than half a second each second.

To get a view of the optimal share to be assigned to a Container, check the current server CPU utilization:

# vzcpucheck

Current CPU utilization: 11142

Power of the node: 125504

The output of this command displays the total number of the so-called CPU units consumed by all running Containers and server processes. This number is calculated by Parallels Server Bare Metal with the help of a special algorithm. The above example illustrates the situation when the server is underused. In other words, the running Containers receive more CPU time than was guaranteed to them.

In the following example, Container 102 is guaranteed to receive about 4% of the CPU time even if the server is fully used, or in other words, if the current CPU utilization equals the power of the server. Besides, Container 102 will not receive more than 25% of the CPU time even if the CPU is not fully loaded:

# pctl set 102 --cpuunits 5000 --cpulimit 25 --save

Saved parameters for Container 102

# pctl start 102

Starting Container ...

Container is mounted

Adding IP address(es): 192.168.1.102

Container start in progress...

# vzcpucheck

Current CPU utilization: 15154

Power of the Node: 125504

Container 102 will receive from 4% to 25% of the server CPU time unless the server is overcommitted, i.e. the running virtual machines and Containers have been promised more CPU units than the power of the server. In this case the Container might get less than 4 percent.

Note: To set the --cpuunits parameter for the server, you should indicate 0 as the Container ID (e.g. pctl set 0 --cpuunits 5000 --save ).