diff options
author | Paul Menage <menage@google.com> | 2007-10-19 06:39:36 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-19 18:53:36 (GMT) |
commit | 817929ec274bcfe771586d338bb31d1659615686 (patch) | |
tree | 5a96ed1afd308016e8720437a00bf2f114e907cb /Documentation | |
parent | a424316ca154317367c7ddf89997d1c80e4a8051 (diff) | |
download | linux-fsl-qoriq-817929ec274bcfe771586d338bb31d1659615686.tar.xz |
Task Control Groups: shared cgroup subsystem group arrays
Replace the struct css_set embedded in task_struct with a pointer; all tasks
that have the same set of memberships across all hierarchies will share a
css_set object, and will be linked via their css_sets field to the "tasks"
list_head in the css_set.
Assuming that many tasks share the same cgroup assignments, this reduces
overall space usage and keeps the size of the task_struct down (three pointers
added to task_struct compared to a non-cgroups kernel, no matter how many
subsystems are registered).
[akpm@linux-foundation.org: fix a printk]
[akpm@linux-foundation.org: build fix]
Signed-off-by: Paul Menage <menage@google.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/cgroups.txt | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/Documentation/cgroups.txt b/Documentation/cgroups.txt index 553727c..98a26f8 100644 --- a/Documentation/cgroups.txt +++ b/Documentation/cgroups.txt @@ -176,7 +176,9 @@ Control Groups extends the kernel as follows: subsystem state is something that's expected to happen frequently and in performance-critical code, whereas operations that require a task's actual cgroup assignments (in particular, moving between - cgroups) are less common. + cgroups) are less common. A linked list runs through the cg_list + field of each task_struct using the css_set, anchored at + css_set->tasks. - A cgroup hierarchy filesystem can be mounted for browsing and manipulation from user space. @@ -252,6 +254,16 @@ linear search to locate an appropriate existing css_set, so isn't very efficient. A future version will use a hash table for better performance. +To allow access from a cgroup to the css_sets (and hence tasks) +that comprise it, a set of cg_cgroup_link objects form a lattice; +each cg_cgroup_link is linked into a list of cg_cgroup_links for +a single cgroup on its cont_link_list field, and a list of +cg_cgroup_links for a single css_set on its cg_link_list. + +Thus the set of tasks in a cgroup can be listed by iterating over +each css_set that references the cgroup, and sub-iterating over +each css_set's task set. + The use of a Linux virtual file system (vfs) to represent the cgroup hierarchy provides for a familiar permission and name space for cgroups, with a minimum of additional kernel code. |