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Task Control Groups: shared cgroup subsystem group arrays

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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>
This commit is contained in:
Paul Menage 2007-10-18 23:39:36 -07:00 • committed by Linus Torvalds
parent a424316ca1
commit 817929ec27
5 changed files with 633 additions and 155 deletions
Download patch file Download diff file Expand all files Collapse all files

89
include/linux/cgroup.h
View file

@ -27,10 +27,19 @@ extern void cgroup_lock(void);
extern void cgroup_unlock(void);
extern void cgroup_fork(struct task_struct *p);
extern void cgroup_fork_callbacks(struct task_struct *p);
extern void cgroup_post_fork(struct task_struct *p);
extern void cgroup_exit(struct task_struct *p, int run_callbacks);
extern struct file_operations proc_cgroup_operations;
/* Define the enumeration of all cgroup subsystems */
#define SUBSYS(_x) _x ## _subsys_id,
enum cgroup_subsys_id {
#include <linux/cgroup_subsys.h>
CGROUP_SUBSYS_COUNT
};
#undef SUBSYS
/* Per-subsystem/per-cgroup state maintained by the system. */
struct cgroup_subsys_state {
/* The cgroup that this subsystem is attached to. Useful
@ -97,6 +106,52 @@ struct cgroup {
struct cgroupfs_root *root;
struct cgroup *top_cgroup;
/*
* List of cg_cgroup_links pointing at css_sets with
* tasks in this cgroup. Protected by css_set_lock
*/
struct list_head css_sets;
};
/* A css_set is a structure holding pointers to a set of
* cgroup_subsys_state objects. This saves space in the task struct
* object and speeds up fork()/exit(), since a single inc/dec and a
* list_add()/del() can bump the reference count on the entire
* cgroup set for a task.
*/
struct css_set {
/* Reference count */
struct kref ref;
/*
* List running through all cgroup groups. Protected by
* css_set_lock
*/
struct list_head list;
/*
* List running through all tasks using this cgroup
* group. Protected by css_set_lock
*/
struct list_head tasks;
/*
* List of cg_cgroup_link objects on link chains from
* cgroups referenced from this css_set. Protected by
* css_set_lock
*/
struct list_head cg_links;
/*
* Set of subsystem states, one for each subsystem. This array
* is immutable after creation apart from the init_css_set
* during subsystem registration (at boot time).
*/
struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
};
/* struct cftype:
@ -157,15 +212,7 @@ int cgroup_is_removed(const struct cgroup *cont);
int cgroup_path(const struct cgroup *cont, char *buf, int buflen);
int __cgroup_task_count(const struct cgroup *cont);
static inline int cgroup_task_count(const struct cgroup *cont)
{
int task_count;
rcu_read_lock();
task_count = __cgroup_task_count(cont);
rcu_read_unlock();
return task_count;
}
int cgroup_task_count(const struct cgroup *cont);
/* Return true if the cgroup is a descendant of the current cgroup */
int cgroup_is_descendant(const struct cgroup *cont);
@ -213,7 +260,7 @@ static inline struct cgroup_subsys_state *cgroup_subsys_state(
static inline struct cgroup_subsys_state *task_subsys_state(
struct task_struct *task, int subsys_id)
{
return rcu_dereference(task->cgroups.subsys[subsys_id]);
return rcu_dereference(task->cgroups->subsys[subsys_id]);
}
static inline struct cgroup* task_cgroup(struct task_struct *task,
@ -226,6 +273,27 @@ int cgroup_path(const struct cgroup *cont, char *buf, int buflen);
int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss);
/* A cgroup_iter should be treated as an opaque object */
struct cgroup_iter {
struct list_head *cg_link;
struct list_head *task;
};
/* To iterate across the tasks in a cgroup:
*
* 1) call cgroup_iter_start to intialize an iterator
*
* 2) call cgroup_iter_next() to retrieve member tasks until it
* returns NULL or until you want to end the iteration
*
* 3) call cgroup_iter_end() to destroy the iterator.
*/
void cgroup_iter_start(struct cgroup *cont, struct cgroup_iter *it);
struct task_struct *cgroup_iter_next(struct cgroup *cont,
struct cgroup_iter *it);
void cgroup_iter_end(struct cgroup *cont, struct cgroup_iter *it);
#else /* !CONFIG_CGROUPS */
static inline int cgroup_init_early(void) { return 0; }
@ -233,6 +301,7 @@ static inline int cgroup_init(void) { return 0; }
static inline void cgroup_init_smp(void) {}
static inline void cgroup_fork(struct task_struct *p) {}
static inline void cgroup_fork_callbacks(struct task_struct *p) {}
static inline void cgroup_post_fork(struct task_struct *p) {}
static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
static inline void cgroup_lock(void) {}