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cpuset: allow to move tasks to empty cpusets 

Currently some cpuset behaviors are not friendly when cpuset is co-mounted
with other cgroup controllers.

Now with this patchset if cpuset is mounted with sane_behavior option,
it behaves differently:

- Tasks will be kept in empty cpusets when hotplug happens and take
  masks of ancestors with non-empty cpus/mems, instead of being moved to
  an ancestor.

- A task can be moved into an empty cpuset, and again it takes masks of
  ancestors, so the user can drop a task into a newly created cgroup without
  having to do anything for it.

As tasks can reside in empy cpusets, here're some rules:

- They can be moved to another cpuset, regardless it's empty or not.

- Though it takes masks from ancestors, it takes other configs from the
  empty cpuset.

- If the ancestors' masks are changed, those tasks will also be updated
  to take new masks.

v2: add documentation in include/linux/cgroup.h

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Li Zefan 2013-06-09 17:16:46 +08:00 committed by Tejun Heo
parent 5c5cc62321
commit 88fa523bff
2 changed files with 10 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/cgroup.h
View File

@ -281,6 +281,9 @@ enum {
* and take masks of ancestors with non-empty cpus/mems, instead of
* being moved to an ancestor.
*
* - cpuset: a task can be moved into an empty cpuset, and again it
* takes masks of ancestors.
*
* - memcg: use_hierarchy is on by default and the cgroup file for
* the flag is not created.
*

9
kernel/cpuset.c
View File

@ -479,7 +479,7 @@ static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
*/
ret = -ENOSPC;
if ((cgroup_task_count(cur->css.cgroup) || cur->attach_in_progress) &&
(cpumask_empty(trial->cpus_allowed) ||
(cpumask_empty(trial->cpus_allowed) &&
nodes_empty(trial->mems_allowed)))
goto out;
@ -1466,8 +1466,13 @@ static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
mutex_lock(&cpuset_mutex);
/*
* We allow to move tasks into an empty cpuset if sane_behavior
* flag is set.
*/
ret = -ENOSPC;
if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
if (!cgroup_sane_behavior(cgrp) &&
(cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
goto out_unlock;
cgroup_taskset_for_each(task, cgrp, tset) {