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-rw-r--r--Documentation/cgroups/cgroups.txt24
1 files changed, 18 insertions, 6 deletions
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt
index 44b8b7af8019..aedf1bd02fdd 100644
--- a/Documentation/cgroups/cgroups.txt
+++ b/Documentation/cgroups/cgroups.txt
@@ -110,22 +110,22 @@ university server with various users - students, professors, system
tasks etc. The resource planning for this server could be along the
following lines:
- CPU : Top cpuset
+ CPU : "Top cpuset"
/ \
CPUSet1 CPUSet2
- | |
- (Profs) (Students)
+ | |
+ (Professors) (Students)
In addition (system tasks) are attached to topcpuset (so
that they can run anywhere) with a limit of 20%
- Memory : Professors (50%), students (30%), system (20%)
+ Memory : Professors (50%), Students (30%), system (20%)
- Disk : Prof (50%), students (30%), system (20%)
+ Disk : Professors (50%), Students (30%), system (20%)
Network : WWW browsing (20%), Network File System (60%), others (20%)
/ \
- Prof (15%) students (5%)
+ Professors (15%) students (5%)
Browsers like Firefox/Lynx go into the WWW network class, while (k)nfsd go
into NFS network class.
@@ -349,6 +349,10 @@ To mount a cgroup hierarchy with all available subsystems, type:
The "xxx" is not interpreted by the cgroup code, but will appear in
/proc/mounts so may be any useful identifying string that you like.
+Note: Some subsystems do not work without some user input first. For instance,
+if cpusets are enabled the user will have to populate the cpus and mems files
+for each new cgroup created before that group can be used.
+
To mount a cgroup hierarchy with just the cpuset and memory
subsystems, type:
# mount -t cgroup -o cpuset,memory hier1 /dev/cgroup
@@ -426,6 +430,14 @@ You can attach the current shell task by echoing 0:
# echo 0 > tasks
+Note: Since every task is always a member of exactly one cgroup in each
+mounted hierarchy, to remove a task from its current cgroup you must
+move it into a new cgroup (possibly the root cgroup) by writing to the
+new cgroup's tasks file.
+
+Note: If the ns cgroup is active, moving a process to another cgroup can
+fail.
+
2.3 Mounting hierarchies by name
--------------------------------