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| author | Serge E. Hallyn <serue@us.ibm.com> | 2008-12-08 22:52:21 +0100 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2008-12-08 23:25:53 +0100 |
| commit | 94d6a5f7341ebaff53d4e41cc81fab37f0d9fbed (patch) | |
| tree | 07b4a016a50f1cc42c6295ec387a26d1a4481381 /Documentation | |
| parent | user namespaces: require cap_set{ug}id for CLONE_NEWUSER (diff) | |
| download | linux-94d6a5f7341ebaff53d4e41cc81fab37f0d9fbed.tar.xz linux-94d6a5f7341ebaff53d4e41cc81fab37f0d9fbed.zip | |
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')
| -rw-r--r-- | Documentation/scheduler/sched-design-CFS.txt | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/scheduler/sched-design-CFS.txt b/Documentation/scheduler/sched-design-CFS.txt index eb471c7a905e..8398ca4ff4ed 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. # #Launch gmplayer (or your favourite movie player) # echo <movie_player_pid> > multimedia/tasks + +8. Implementation note: user namespaces + +User namespaces are intended to be hierarchical. But they are currently +only partially implemented. Each of those has ramifications for CFS. + +First, since user namespaces are hierarchical, the /sys/kernel/uids +presentation is inadequate. Eventually we will likely want to use sysfs +tagging to provide private views of /sys/kernel/uids within each user +namespace. + +Second, the hierarchical nature is intended to support completely +unprivileged use of user namespaces. So if using user groups, then +we want the users in a user namespace to be children of the user +who created it. + +That is currently unimplemented. So instead, every user in a new +user namespace will receive 1024 shares just like any user in the +initial user namespace. Note that at the moment creation of a new +user namespace requires each of CAP_SYS_ADMIN, CAP_SETUID, and +CAP_SETGID. |