Docker 101 : An example of "Cgroups" - Control Groups for docker containers

An example of cgroups and container:

We can use the "docker run" command to limit the cpu usage of a container using the cgroup subsystem cpu.shares in the cgroup file system "/sys/fs/cgroup/cpu" :

For a debian image, we use the "--cpu-shares" option to limits the "cpu time" a docker container gets:

The above command runs an interactive shell "-it" inside the "debian" image.

Inside the container:

We could verify the value of the "--cpu-shares" from inside the container:

Checking the "--cpu-shares" of the container from the host:

Linux created a subdirectory for docker and another one for the container as we can see from the alphanumerical container ID value.


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