How to Limit CPU and Memory Usage With Cgroups on Debian/Ubuntu Cgroups is a flexible Linux kernel feature to limit, police and account resources usage. A cgroup is a set of tasks for a subsystems, that is typically a resource controller.
A file system of type cgroup is mounted and all operations are run over it.
Installation The installation can be done using any of libcgroup, cgmanager or systemd.
Usage They can be used in multiple ways
By accessing the cgroup filesystem directly. Using the cgm client (part of the cgmanager). Via cgcreate, cgexec and cgclassify (part of cgroup-tools). Via cgconfig.conf and cgrules.conf (also part of cgroup-tools). We will use this last option, so install cgroup-tools with
sudo apt-get install cgroup-tools Debian, by default, disables the memory controller, we can enable it adding the following in /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="quiet cgroup_enable=memory swapaccount=1" So, update Grub
sudo update-grub Now the environment and tools are ready, we will define some “roles” in /etc/cgconfig.conf
group app/editor { cpu { cpu.shares = 500; } memory { memory.limit_in_bytes = 1000000000; } }
group app/browser { cpu { cpu.shares = 300; } memory { memory.limit_in_bytes = 1000000000; } }
group app/util { cpu { cpu.shares = 300; } memory { memory.limit_in_bytes = 500000000; } } The maximum value for cpu.shares is 1000, so 300 is setting as 30% the usage limit for an application with this “role”. memory.limit_in_bytes is self descriptive.
We will associate these “roles” and the applications in /etc/cgrules.conf
*:emacs cpu,memory app/editor/ *:conkeror cpu,memory app/browser/ *:firefox cpu,memory app/browser/ *:slack cpu,memory app/util/ *:dropbox cpu,memory app/util/ Now we need apply the rules with the commands
cgconfigparser -l /etc/cgconfig.conf cgrulesengd Add them in /etc/rc.local for applying on reboot.
That’s it!
We can check if our new rules were applied using
cat /proc/pidof dropbox/cgroup | grep app
And we can check the memory usage of a process with
smem -P dropbox
References
https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt https://www.kernel.org/doc/Documentation/cgroup-v1/memory.txt https://wiki.archlinux.org/index.php/cgroups moby/moby#396 (comment)