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Limiting process resource usage in AL2027 using cgroups - Amazon Linux 2027
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Limiting process resource usage in AL2027 using cgroups

AL2027 Preview

AL2027 is currently available for preview. It is intended for evaluation and testing only and is not recommended for production workloads.

While it is recommended to use Resource control with systemd, this section covers basic usage of the base libcgroup-tools utilities to limit CPU and memory usage of processes. Both methods are alternatives to using the cpulimit utility.

The following example covers running the stress-ng stress test (from the stress-ng package) while limiting its CPU and memory usage using utilities from the libcgroup-tools package, and the tunables in sysfs.

Use libcgroup-tools on the command line to limit resource usage

  1. Install the libcgroup-tools package.

    sudo dnf install libcgroup-tools

  2. Create a cgroup with the memory and cpu controllers, and give it a name (our-example-limits). Using the -a and -t options to allow the ec2-user user to control the tunables of the cgroup.

    sudo cgcreate -a ec2-user -t ec2-user -g memory,cpu:our-example-limits

    There is now a /sys/fs/cgroup/our-example-limits/ directory that contains files that can be used to control each tunable.

  3. Limit memory usage of all processes in our cgroup to 100 million bytes.

    echo 100000000 > /sys/fs/cgroup/our-example-limits/memory.max

  4. Limit CPU usage of all processes in our cgroup to 10%. The format of the cpu.max file is $MAX $PERIOD, limiting the group to consuming $MAX for every $PERIOD.

    echo 10000 100000 > /sys/fs/cgroup/our-example-limits/cpu.max

  5. The following example runs stress-ng (which can be installed by running dnf install -y stress-ng) in the our-example-limits cgroup. While the stress-ng command is running, you can observe using top that it is limited to 10% of CPU time.

    sudo cgexec -g memory,cpu:our-example-limits stress-ng --cpu 1

  6. Clean up by removing the cgroup.

    sudo cgdelete -g memory,cpu:our-example-limits

The Linux Kernel documentation for cgroup-v2 on the kernel.org website contains extensive details about how they work. The documentation of the cpu and memory controllers, both on the kernel.org website, covers the details of how to use each tunable option.