From d311c798b7d4fb4ad7723a845cb871e306b0688d Mon Sep 17 00:00:00 2001 From: Michael Kerrisk Date: Tue, 9 Jan 2018 21:37:31 +0100 Subject: [PATCH] cgroups.7: Add a more complete description of cgroup v1 named hierarchies Signed-off-by: Michael Kerrisk --- man7/cgroups.7 | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/man7/cgroups.7 b/man7/cgroups.7 index 6950cefd3..eeef6b585 100644 --- a/man7/cgroups.7 +++ b/man7/cgroups.7 @@ -125,16 +125,6 @@ which is a child of Under each cgroup directory is a set of files which can be read or written to, reflecting resource limits and a few general cgroup properties. -.PP -In addition, in cgroups v1, -cgroups can be mounted with no bound controller, in which case -they serve only to track processes. -(See the discussion of release notification below.) -An example of this is the -.I name=systemd -cgroup which is used by -.BR systemd (1) -to track services and user sessions. .\" .SS Tasks (threads) versus processes In cgroups v1, a distinction is drawn between @@ -507,6 +497,26 @@ At the time when a new cgroup is created, the value in this file is inherited from the corresponding file in the parent cgroup. .\" +.SS Cgroup v1 named hierarchies +In cgroups v1, +it is possible to mount a cgroup hierarchy that has no attached controllers: +.PP +.in +4n +.EX +mount -t cgroup -o none,name=somename none /some/mount/point +.EE +.in +.PP +Multiple instances of such hierarchies can be mounted; +each hierarchy must have a unique name. +The only purpose of such hierarchies is to track processes. +(See the discussion of release notification below.) +An example of this is the +.I name=systemd +cgroup hierarchy that is used by +.BR systemd (1) +to track services and user sessions. +.\" .SH CGROUPS VERSION 2 In cgroups v2, all mounted controllers reside in a single unified hierarchy.