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cgroups.7: Prefer "controller" over "subsystem" 

Replace various uses of "subsystem" with "controller". The
former too was originally used in describing cgroups, but it
is vague to the point of ambiguity. The latter term is a
little less ambiguous.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2016-10-07 11:46:40 +02:00
parent 1a90a85efc
commit 55f52de8f6
1 changed files with 19 additions and 19 deletions
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38
man7/cgroups.7
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@ -55,7 +55,7 @@ Subsystems are sometimes also known as
.IR "resource controllers" .IR "resource controllers"
(or simply, controllers). (or simply, controllers).
The cgroups for a subsystem are arranged in a The cgroups for a controller are arranged in a
.IR hierarchy . .IR hierarchy .
This hierarchy is defined by creating, removing, and This hierarchy is defined by creating, removing, and
renaming subdirectories within the cgroup filesystem. renaming subdirectories within the cgroup filesystem.
@ -69,10 +69,10 @@ by descendant cgroups.
.\" .\"
.SS Cgroups version 1 and version 2 .SS Cgroups version 1 and version 2
The initial release of the cgroups implementation was in Linux 2.6.24. The initial release of the cgroups implementation was in Linux 2.6.24.
Over time, various cgroup subsystems have been added Over time, various cgroup controllers have been added
to allow the management of various types of resources. to allow the management of various types of resources.
However, the development of these subsystems was largely uncoordinated, However, the development of these controllers was largely uncoordinated,
with the result that many inconsistencies arose between subsystems with the result that many inconsistencies arose between controllers
and management of the cgroup hierarchies became rather complex. and management of the cgroup hierarchies became rather complex.
(A longer description of these problems can be found in (A longer description of these problems can be found in
the kernel source file the kernel source file
@ -127,7 +127,7 @@ written to, reflecting resource limits and a few general cgroup
properties. properties.
In addition, in cgroups v1, In addition, in cgroups v1,
cgroups can be mounted with no bound subsystem, in which case cgroups can be mounted with no bound controller, in which case
they serve only to track processes. they serve only to track processes.
An example of this is the An example of this is the
.I name=systemd .I name=systemd
@ -154,23 +154,23 @@ Cgroups v2 allows manipulation of cgroup membership only for processes
all threads in the process). all threads in the process).
.\" .\"
.SS Mounting .SS Mounting
To be available, a given cgroup subsystem must be compiled into the To be available, a given cgroup controller must be compiled into the
kernel. kernel.
Since they are exposed through a virtual filesystem, subsystems Since they are exposed through a virtual filesystem, controllers
must be mounted before they can be controlled. must be mounted before they can be controlled.
The usual place for this is under The usual place for this is under
.IR /sys/fs/cgroup . .IR /sys/fs/cgroup .
If all the desired subsystems can be comounted, If all the desired controllers can be comounted,
then one can do so with the following command: then one can do so with the following command:
mount \-t cgroup \-o all cgroup /sys/fs/cgroup mount \-t cgroup \-o all cgroup /sys/fs/cgroup
(One can achieve the same result by omitting (One can achieve the same result by omitting
.IR "\-o all" , .IR "\-o all" ,
since it is the default if subsystems are explicitly specified.) since it is the default if controllers are explicitly specified.)
If multiple, separately mounted subsystems are desired, then this is If multiple, separately mounted controllers are desired, then this is
usually done in per-subsystem subdirectories. usually done in per-controller subdirectories.
This requires first mounting a tmpfs under This requires first mounting a tmpfs under
.I /sys/fs/cgroup .I /sys/fs/cgroup
so that subdirectories can be created. so that subdirectories can be created.
@ -191,12 +191,12 @@ done
.in .in
.fi .fi
Comounting subsystems has the effect that a process is in the same cgroup for Comounting controllers has the effect that a process is in the same cgroup for
all comounted subsystems. all comounted controllers.
Separately mounting subsystems allows a process to Separately mounting controllers allows a process to
be in cgroup be in cgroup
.I /foo1 .I /foo1
for one subsystem while being in for one controller while being in
.I /foo2/foo3 .I /foo2/foo3
for another. for another.
.\" .\"
@ -334,8 +334,8 @@ For more changes, please see the
.I Documentation/cgroup-v2.txt .I Documentation/cgroup-v2.txt
file in the kernel source. file in the kernel source.
.\" .\"
.SS Cgroups version 1 subsystems .SS Cgroups version 1 controllers
Each of the cgroups version 1 subsystems is governed Each of the cgroups version 1 controllers is governed
by a kernel configuration option (listed below). by a kernel configuration option (listed below).
Additionally, the availability of the cgroups feature is governed by the Additionally, the availability of the cgroups feature is governed by the
.BR CONFIG_CGROUPS .BR CONFIG_CGROUPS
@ -510,7 +510,7 @@ For each cgroup hierarchy of which the process is a member,
there is one entry containing three there is one entry containing three
colon-separated fields of the form: colon-separated fields of the form:
hierarchy-ID:subsystem-list:cgroup-path hierarchy-ID:controller-list:cgroup-path
For example: For example:
.nf .nf
@ -530,7 +530,7 @@ that can be matched to a hierarchy ID in
For the cgroups version 2 hierarchy, this field contains the value 0. For the cgroups version 2 hierarchy, this field contains the value 0.
.IP 2. .IP 2.
For cgroups version 1 hierarchies, For cgroups version 1 hierarchies,
this field contains a comma-separated list of the subsystems this field contains a comma-separated list of the controllers
bound to the hierarchy. bound to the hierarchy.
For the cgroups version 2 hierarchy, this field is empty. For the cgroups version 2 hierarchy, this field is empty.
.IP 3. .IP 3.