Displays information about the control groups
/proc/cgroups file is a read-only file that lives in the
/proc directory. It provides
information about the control groups subsystem of the Linux kernel.
Control groups, or cgroups, are a kernel feature that limits and isolates the resource usage (CPU, memory, disk I/O, network, etc.) of process groups.
What Does /proc/cgroups Contain?
/proc/cgroups file contains tab-separated values that indicate the subsystem name, hierarchy, the number of
cgroups for each hierarchy, and the number of tasks for each. The subsystem names can
#subsys_name hierarchy num_cgroups enabled
cpuset 4 10 1
cpu 2 76 1
cpuacct 6 76 1
blkio 3 76 1
memory 5 183 1
devices 8 76 1
freezer 7 76 1
Why is /proc/cgroups Important?
/proc/cgroups file is crucial because it allows us to monitor and control the resources that each
process and its children can use. This is especially useful in multi-user systems or systems running multiple services,
where resource allocation can significantly impact performance and stability.
To view the contents of the
/proc/cgroups file, you can use the cat command:
The output will give you an overview of the control groups subsystems currently active on your system.
Typical Problems Diagnosed with /proc/cgroups
One common issue you might encounter is overconsumption of resources by certain processes, leading to system instability
or performance degradation. By examining the
/proc/cgroups file, you can identify which cgroups are consuming more
resources and take appropriate actions.
For example, if you notice that a particular cgroup is consuming a large amount of memory, this might indicate that there's a memory leak in one of the processes within that cgroup. In this case, you can use cgroups to limit the amount of memory that the problematic cgroup can use, preventing it from affecting the rest of the system.
/proc/cgroups file is a powerful tool in any Linux admin's arsenal. By understanding its purpose and how to use
it, you can effectively manage resource allocation on your server, diagnose potential issues, and ensure a smooth,