https://github.com/okeuday/cgroups

Erlang native cgroups interface
https://github.com/okeuday/cgroups

cgroups erlang linux

Last synced: 3 months ago
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Erlang native cgroups interface

• Host: GitHub
• URL: https://github.com/okeuday/cgroups
• Owner: okeuday
• License: mit
• Created: 2016-09-14T03:15:55.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2023-10-26T18:24:32.000Z (about 1 year ago)
• Last Synced: 2024-10-14T03:29:55.761Z (3 months ago)
• Topics: cgroups, erlang, linux
• Language: Erlang
• Size: 90.8 KB
• Stars: 13
• Watchers: 4
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.markdown
  • License: LICENSE

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README

        
Erlang cgroups interface

========================

An interface for cgroups manipulation that handles cgroup version details

(i.e., differences between [v1](https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt) and [v2](https://github.com/torvalds/linux/blob/master/Documentation/admin-guide/cgroup-v2.rst))

and provides safe usage of the cgroups filesystem mount.

Build

-----

    rebar compile

Example

-------

Update or create the cgroup "group1/nested1" with the OS pid 19368,

then delete the cgroup path after moving the OS pid back to the root cgroup

(executed as root).

    # erl -pz ebin

    1> application:start(cgroups).

    2> OSPid0 = 19368.

    3> CGroupPath = "group1/nested1".

    4> {ok, CGroups} = cgroups:new().

    5> MemoryLimit = case cgroups:version(CGroups) of 1 -> "memory.limit_in_bytes"; 2 -> "memory.high" end.

    6> cgroups:update_or_create(CGroupPath,

                                [OSPid0],

                                [{MemoryLimit, "10000000"}],

                                CGroups).

    7> cgroups:update("", [OSPid0], [], CGroups).

    8> cgroups:delete_recursive(CGroupPath, CGroups).

    9> cgroups:destroy(CGroups).

Troubleshooting

---------------

**`cgroups:update/4` and `cgroups:update_or_create/4` Errors:**

* Either root execution of beam.smp or

  `setcap cap_sys_admin=+ep /path/to/beam.smp` before execution is required

  for most usage of cgroups

* A Linux/systemd setup may have the control group setup mode set to `hybrid`

  due to it being the [recommended default](https://github.com/systemd/systemd/blob/v239/NEWS#L1365)

  for distributions.  However, that mode blocks the use of cgroup controllers

  (the file `/sys/fs/cgroup/unified/cgroup.controllers` is empty)

  because the cgroup controllers can only be [mounted in one hierarchy](https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html#mounting)

  (v1 or v2).  If cgroup v1 should be used, the Linux kernel argument

  `systemd.legacy_systemd_cgroup_controller=1` can be used.

  If cgroup v2 should be used, the Linux kernel argument

  `systemd.unified_cgroup_hierarchy=1` can be used

  (with systemd >= `v226` and kernel >= `4.2`) or

  `cgroup_no_v1=all` can be used (with kernel >= `4.6`).

* Any non-root use should only use `cgroups:update/4` with more limited

  controllers (memory, pids, possibly cpu and/or io) and all OS pids added

  elsewhere as root

Author

------

Michael Truog (mjtruog at protonmail dot com)

License

-------

MIT License