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authorSerge E. Hallyn <serue@us.ibm.com>2008-12-08 16:52:21 -0500
committerJames Morris <jmorris@namei.org>2008-12-08 17:25:53 -0500
commit94d6a5f7341ebaff53d4e41cc81fab37f0d9fbed (patch)
tree07b4a016a50f1cc42c6295ec387a26d1a4481381 /Documentation/scheduler
parent7657d90497f98426af17f0ac633a9b335bb7a8fb (diff)
user namespaces: document CFS behavior
Documented the currently bogus state of support for CFS user groups with user namespaces. In particular, all users in a user namespace should be children of the user which created the user namespace. This is yet to be implemented. Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Acked-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'Documentation/scheduler')
-rw-r--r--Documentation/scheduler/sched-design-CFS.txt21
1 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/scheduler/sched-design-CFS.txt b/Documentation/scheduler/sched-design-CFS.txt
index eb471c7a905..8398ca4ff4e 100644
--- a/Documentation/scheduler/sched-design-CFS.txt
+++ b/Documentation/scheduler/sched-design-CFS.txt
@@ -273,3 +273,24 @@ task groups and modify their CPU share using the "cgroups" pseudo filesystem.
273 273
274 # #Launch gmplayer (or your favourite movie player) 274 # #Launch gmplayer (or your favourite movie player)
275 # echo <movie_player_pid> > multimedia/tasks 275 # echo <movie_player_pid> > multimedia/tasks
276
2778. Implementation note: user namespaces
278
279User namespaces are intended to be hierarchical. But they are currently
280only partially implemented. Each of those has ramifications for CFS.
281
282First, since user namespaces are hierarchical, the /sys/kernel/uids
283presentation is inadequate. Eventually we will likely want to use sysfs
284tagging to provide private views of /sys/kernel/uids within each user
285namespace.
286
287Second, the hierarchical nature is intended to support completely
288unprivileged use of user namespaces. So if using user groups, then
289we want the users in a user namespace to be children of the user
290who created it.
291
292That is currently unimplemented. So instead, every user in a new
293user namespace will receive 1024 shares just like any user in the
294initial user namespace. Note that at the moment creation of a new
295user namespace requires each of CAP_SYS_ADMIN, CAP_SETUID, and
296CAP_SETGID.