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3.6. freezer

The freezer subsystem suspends or resumes tasks in a cgroup.
freezer.state is only available in non-root cgroups and has three possible values:
  • FROZEN — tasks in the cgroup are suspended.
  • FREEZING — the system is in the process of suspending tasks in the cgroup.
  • THAWED — tasks in the cgroup have resumed.
To suspend a specific process:
  1. Move that process to a cgroup in a hierarchy which has the freezer subsystem attached to it.
  2. Freeze that particular cgroup to suspend the process contained in it.
It is not possible to move a process into a suspended (frozen) cgroup.
Note that while the FROZEN and THAWED values can be written to freezer.state, FREEZING cannot be written, only read.