kernel-ark/include/linux/cgroup.h
Paul Menage 8bab8dded6 cgroups: add cgroup support for enabling controllers at boot time
The effects of cgroup_disable=foo are:

- foo isn't auto-mounted if you mount all cgroups in a single hierarchy
- foo isn't visible as an individually mountable subsystem

As a result there will only ever be one call to foo->create(), at init time;
all processes will stay in this group, and the group will never be mounted on
a visible hierarchy.  Any additional effects (e.g.  not allocating metadata)
are up to the foo subsystem.

This doesn't handle early_init subsystems (their "disabled" bit isn't set be,
but it could easily be extended to do so if any of the early_init systems
wanted it - I think it would just involve some nastier parameter processing
since it would occur before the command-line argument parser had been run.

Hugh said:

  Ballpark figures, I'm trying to get this question out rather than
  processing the exact numbers: CONFIG_CGROUP_MEM_RES_CTLR adds 15% overhead
  to the affected paths, booting with cgroup_disable=memory cuts that back to
  1% overhead (due to slightly bigger struct page).

  I'm no expert on distros, they may have no interest whatever in
  CONFIG_CGROUP_MEM_RES_CTLR=y; and the rest of us can easily build with or
  without it, or apply the cgroup_disable=memory patches.

Unix bench's execl test result on x86_64 was

== just after boot without mounting any cgroup fs.==
mem_cgorup=off : Execl Throughput       43.0     3150.1      732.6
mem_cgroup=on  : Execl Throughput       43.0     2932.6      682.0
==

[lizf@cn.fujitsu.com: fix boot option parsing]
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Sudhir Kumar <skumar@linux.vnet.ibm.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-04 14:46:26 -07:00

343 lines
9.9 KiB
C

#ifndef _LINUX_CGROUP_H
#define _LINUX_CGROUP_H
/*
* cgroup interface
*
* Copyright (C) 2003 BULL SA
* Copyright (C) 2004-2006 Silicon Graphics, Inc.
*
*/
#include <linux/sched.h>
#include <linux/kref.h>
#include <linux/cpumask.h>
#include <linux/nodemask.h>
#include <linux/rcupdate.h>
#include <linux/cgroupstats.h>
#include <linux/prio_heap.h>
#ifdef CONFIG_CGROUPS
struct cgroupfs_root;
struct cgroup_subsys;
struct inode;
extern int cgroup_init_early(void);
extern int cgroup_init(void);
extern void cgroup_init_smp(void);
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 int cgroupstats_build(struct cgroupstats *stats,
struct dentry *dentry);
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
* for subsystems that want to know about the cgroup
* hierarchy structure */
struct cgroup *cgroup;
/* State maintained by the cgroup system to allow
* subsystems to be "busy". Should be accessed via css_get()
* and css_put() */
atomic_t refcnt;
unsigned long flags;
};
/* bits in struct cgroup_subsys_state flags field */
enum {
CSS_ROOT, /* This CSS is the root of the subsystem */
};
/*
* Call css_get() to hold a reference on the cgroup;
*
*/
static inline void css_get(struct cgroup_subsys_state *css)
{
/* We don't need to reference count the root state */
if (!test_bit(CSS_ROOT, &css->flags))
atomic_inc(&css->refcnt);
}
/*
* css_put() should be called to release a reference taken by
* css_get()
*/
extern void __css_put(struct cgroup_subsys_state *css);
static inline void css_put(struct cgroup_subsys_state *css)
{
if (!test_bit(CSS_ROOT, &css->flags))
__css_put(css);
}
struct cgroup {
unsigned long flags; /* "unsigned long" so bitops work */
/* count users of this cgroup. >0 means busy, but doesn't
* necessarily indicate the number of tasks in the
* cgroup */
atomic_t count;
/*
* We link our 'sibling' struct into our parent's 'children'.
* Our children link their 'sibling' into our 'children'.
*/
struct list_head sibling; /* my parent's children */
struct list_head children; /* my children */
struct cgroup *parent; /* my parent */
struct dentry *dentry; /* cgroup fs entry */
/* Private pointers for each registered subsystem */
struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
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;
/*
* Linked list running through all cgroups that can
* potentially be reaped by the release agent. Protected by
* release_list_lock
*/
struct list_head release_list;
};
/* 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:
*
* The files in the cgroup filesystem mostly have a very simple read/write
* handling, some common function will take care of it. Nevertheless some cases
* (read tasks) are special and therefore I define this structure for every
* kind of file.
*
*
* When reading/writing to a file:
* - the cgroup to use is file->f_dentry->d_parent->d_fsdata
* - the 'cftype' of the file is file->f_dentry->d_fsdata
*/
#define MAX_CFTYPE_NAME 64
struct cftype {
/* By convention, the name should begin with the name of the
* subsystem, followed by a period */
char name[MAX_CFTYPE_NAME];
int private;
int (*open) (struct inode *inode, struct file *file);
ssize_t (*read) (struct cgroup *cgrp, struct cftype *cft,
struct file *file,
char __user *buf, size_t nbytes, loff_t *ppos);
/*
* read_uint() is a shortcut for the common case of returning a
* single integer. Use it in place of read()
*/
u64 (*read_uint) (struct cgroup *cgrp, struct cftype *cft);
ssize_t (*write) (struct cgroup *cgrp, struct cftype *cft,
struct file *file,
const char __user *buf, size_t nbytes, loff_t *ppos);
/*
* write_uint() is a shortcut for the common case of accepting
* a single integer (as parsed by simple_strtoull) from
* userspace. Use in place of write(); return 0 or error.
*/
int (*write_uint) (struct cgroup *cgrp, struct cftype *cft, u64 val);
int (*release) (struct inode *inode, struct file *file);
};
struct cgroup_scanner {
struct cgroup *cg;
int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan);
void (*process_task)(struct task_struct *p,
struct cgroup_scanner *scan);
struct ptr_heap *heap;
};
/* Add a new file to the given cgroup directory. Should only be
* called by subsystems from within a populate() method */
int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
const struct cftype *cft);
/* Add a set of new files to the given cgroup directory. Should
* only be called by subsystems from within a populate() method */
int cgroup_add_files(struct cgroup *cgrp,
struct cgroup_subsys *subsys,
const struct cftype cft[],
int count);
int cgroup_is_removed(const struct cgroup *cgrp);
int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
int cgroup_task_count(const struct cgroup *cgrp);
/* Return true if the cgroup is a descendant of the current cgroup */
int cgroup_is_descendant(const struct cgroup *cgrp);
/* Control Group subsystem type. See Documentation/cgroups.txt for details */
struct cgroup_subsys {
struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss,
struct cgroup *cgrp);
void (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
int (*can_attach)(struct cgroup_subsys *ss,
struct cgroup *cgrp, struct task_struct *tsk);
void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup *old_cgrp, struct task_struct *tsk);
void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);
void (*exit)(struct cgroup_subsys *ss, struct task_struct *task);
int (*populate)(struct cgroup_subsys *ss,
struct cgroup *cgrp);
void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
int subsys_id;
int active;
int disabled;
int early_init;
#define MAX_CGROUP_TYPE_NAMELEN 32
const char *name;
/* Protected by RCU */
struct cgroupfs_root *root;
struct list_head sibling;
void *private;
};
#define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
#include <linux/cgroup_subsys.h>
#undef SUBSYS
static inline struct cgroup_subsys_state *cgroup_subsys_state(
struct cgroup *cgrp, int subsys_id)
{
return cgrp->subsys[subsys_id];
}
static inline struct cgroup_subsys_state *task_subsys_state(
struct task_struct *task, int subsys_id)
{
return rcu_dereference(task->cgroups->subsys[subsys_id]);
}
static inline struct cgroup* task_cgroup(struct task_struct *task,
int subsys_id)
{
return task_subsys_state(task, subsys_id)->cgroup;
}
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.
*
* Or, call cgroup_scan_tasks() to iterate through every task in a cpuset.
* - cgroup_scan_tasks() holds the css_set_lock when calling the test_task()
* callback, but not while calling the process_task() callback.
*/
void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it);
struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
struct cgroup_iter *it);
void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);
int cgroup_scan_tasks(struct cgroup_scanner *scan);
int cgroup_attach_task(struct cgroup *, struct task_struct *);
#else /* !CONFIG_CGROUPS */
static inline int cgroup_init_early(void) { return 0; }
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) {}
static inline void cgroup_unlock(void) {}
static inline int cgroupstats_build(struct cgroupstats *stats,
struct dentry *dentry)
{
return -EINVAL;
}
#endif /* !CONFIG_CGROUPS */
#endif /* _LINUX_CGROUP_H */