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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-10-07 19:56:38 +0200 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-10-08 14:08:23 +0200 |
| commit | dddb7ea1fc7160f4decc933b76cfa611951dc037 (patch) | |
| tree | 9ba0cbd3b4b5f1282f378bbac2215bdd01bd4284 | |
| parent | 2befa495c2bce914316569f05e1f083141d90f55 (diff) | |
| download | man-pages-dddb7ea1fc7160f4decc933b76cfa611951dc037.tar.gz | |
cgroups.7: Document cgroups v2 unified hierarchy
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
| -rw-r--r-- | man7/cgroups.7 | 29 |
1 files changed, 26 insertions, 3 deletions
diff --git a/man7/cgroups.7 b/man7/cgroups.7 index 7d6be88dc3..531d3bb9c5 100644 --- a/man7/cgroups.7 +++ b/man7/cgroups.7 @@ -453,15 +453,18 @@ under both the v1 and the v2 hierarchies. The new behaviors in cgroups v2 are summarized here, and in some cases elaborated in the following subsections. .IP 1. 3 +Cgroups v2 provides a unified hiearchy against +which all controllers are mounted. +.IP 2. "Internal" processes are not permitted. With the exception of the root cgroup, processes may reside only in leaf nodes (cgroups that do not themselves contain child cgroups). -.IP 2. +.IP 3. Active cgroups must be specified via the files .IR cgroup.controllers and .IR cgroup.subtree_control . -.IP 3. +.IP 4. The .I tasks file has been removed. @@ -470,7 +473,7 @@ In addition, the file that is employed by the .I cpuset controller has been removed. -.IP 4. +.IP 5. An improved mechanism for notification of empty cgroups is provided by the .IR cgroup.events file. @@ -479,6 +482,25 @@ For more changes, see the .I Documentation/cgroup-v2.txt file in the kernel source. .\" +.SS Cgroups v2 unified hierarchy +In cgroups v1, the ability to mount different controllers +against different hierarchies was intended to allow great flexibility +for application design. +In practice, though, the flexibility turned out to less useful than expected, +and in many cases added complexity. +Therefore, in cgroups v2, +all available controllers are mounted against a single hierarchy. +The available controllers are automatically mounted, +meaning that it is not necessary (or possible) to specify the controllers +when mounting the cgroup v2 filesystem using a command such as the following: + + mount -t cgroup2 none /mnt/cgroup2 + +A cgroup v2 controller is available only if it is not currently in use +via a mount against a cgroup v1 hierarchy. +Or, to put things another way, it is not possible to employ +the same controller against both a v1 hierarchy and the unified v2 hierarchy. +.\" .SS Cgroups v2 "no internal processes" rule With the exception of the root cgroup, processes may reside only in leaf nodes (cgroups that do not themselves contain child cgroups). @@ -528,6 +550,7 @@ then it cannot be enabled in .IR /A/B/C . .\" .SS Cgroups v2 events file +.\" FIXME The following text is wrong A new feature in cgroups v2 is the .I cgroup.populated file. |