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cgroups (Control Groups)

cgroups provide fine-grained resource control for containers and processes, including CPU, memory, and I/O limits.

Key Concepts​

  • Memory limit: Prevents a container from using more RAM than allowed.
  • CPU shares: Allocates CPU bandwidth among containers.
  • blkio: Limits block device I/O throughput.

Input:

cat /sys/fs/cgroup/memory/docker/<container_id>/memory.limit_in_bytes

Output:

536870912

Indicates memory limit in bytes for a container (512MB here).

Input:

docker run -d --memory=512m --cpus=1 nginx

Restricts container to 512MB RAM and 1 CPU core.

References: