![Paul Menage](/assets/img/avatar_default.png)
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>
343 lines
9.9 KiB
C
343 lines
9.9 KiB
C
#ifndef _LINUX_CGROUP_H
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#define _LINUX_CGROUP_H
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/*
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* cgroup interface
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*
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* Copyright (C) 2003 BULL SA
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* Copyright (C) 2004-2006 Silicon Graphics, Inc.
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*
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*/
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#include <linux/sched.h>
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#include <linux/kref.h>
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#include <linux/cpumask.h>
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#include <linux/nodemask.h>
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#include <linux/rcupdate.h>
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#include <linux/cgroupstats.h>
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#include <linux/prio_heap.h>
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#ifdef CONFIG_CGROUPS
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struct cgroupfs_root;
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struct cgroup_subsys;
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struct inode;
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extern int cgroup_init_early(void);
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extern int cgroup_init(void);
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extern void cgroup_init_smp(void);
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extern void cgroup_lock(void);
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extern void cgroup_unlock(void);
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extern void cgroup_fork(struct task_struct *p);
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extern void cgroup_fork_callbacks(struct task_struct *p);
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extern void cgroup_post_fork(struct task_struct *p);
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extern void cgroup_exit(struct task_struct *p, int run_callbacks);
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extern int cgroupstats_build(struct cgroupstats *stats,
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struct dentry *dentry);
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extern struct file_operations proc_cgroup_operations;
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/* Define the enumeration of all cgroup subsystems */
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#define SUBSYS(_x) _x ## _subsys_id,
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enum cgroup_subsys_id {
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#include <linux/cgroup_subsys.h>
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CGROUP_SUBSYS_COUNT
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};
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#undef SUBSYS
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/* Per-subsystem/per-cgroup state maintained by the system. */
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struct cgroup_subsys_state {
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/* The cgroup that this subsystem is attached to. Useful
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* for subsystems that want to know about the cgroup
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* hierarchy structure */
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struct cgroup *cgroup;
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/* State maintained by the cgroup system to allow
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* subsystems to be "busy". Should be accessed via css_get()
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* and css_put() */
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atomic_t refcnt;
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unsigned long flags;
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};
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/* bits in struct cgroup_subsys_state flags field */
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enum {
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CSS_ROOT, /* This CSS is the root of the subsystem */
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};
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/*
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* Call css_get() to hold a reference on the cgroup;
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*
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*/
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static inline void css_get(struct cgroup_subsys_state *css)
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{
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/* We don't need to reference count the root state */
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if (!test_bit(CSS_ROOT, &css->flags))
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atomic_inc(&css->refcnt);
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}
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/*
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* css_put() should be called to release a reference taken by
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* css_get()
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*/
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extern void __css_put(struct cgroup_subsys_state *css);
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static inline void css_put(struct cgroup_subsys_state *css)
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{
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if (!test_bit(CSS_ROOT, &css->flags))
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__css_put(css);
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}
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struct cgroup {
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unsigned long flags; /* "unsigned long" so bitops work */
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/* count users of this cgroup. >0 means busy, but doesn't
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* necessarily indicate the number of tasks in the
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* cgroup */
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atomic_t count;
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/*
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* We link our 'sibling' struct into our parent's 'children'.
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* Our children link their 'sibling' into our 'children'.
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*/
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struct list_head sibling; /* my parent's children */
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struct list_head children; /* my children */
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struct cgroup *parent; /* my parent */
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struct dentry *dentry; /* cgroup fs entry */
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/* Private pointers for each registered subsystem */
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struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
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struct cgroupfs_root *root;
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struct cgroup *top_cgroup;
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/*
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* List of cg_cgroup_links pointing at css_sets with
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* tasks in this cgroup. Protected by css_set_lock
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*/
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struct list_head css_sets;
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/*
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* Linked list running through all cgroups that can
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* potentially be reaped by the release agent. Protected by
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* release_list_lock
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*/
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struct list_head release_list;
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};
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/* A css_set is a structure holding pointers to a set of
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* cgroup_subsys_state objects. This saves space in the task struct
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* object and speeds up fork()/exit(), since a single inc/dec and a
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* list_add()/del() can bump the reference count on the entire
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* cgroup set for a task.
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*/
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struct css_set {
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/* Reference count */
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struct kref ref;
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/*
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* List running through all cgroup groups. Protected by
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* css_set_lock
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*/
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struct list_head list;
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/*
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* List running through all tasks using this cgroup
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* group. Protected by css_set_lock
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*/
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struct list_head tasks;
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/*
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* List of cg_cgroup_link objects on link chains from
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* cgroups referenced from this css_set. Protected by
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* css_set_lock
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*/
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struct list_head cg_links;
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/*
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* Set of subsystem states, one for each subsystem. This array
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* is immutable after creation apart from the init_css_set
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* during subsystem registration (at boot time).
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*/
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struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
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};
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/* struct cftype:
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*
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* The files in the cgroup filesystem mostly have a very simple read/write
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* handling, some common function will take care of it. Nevertheless some cases
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* (read tasks) are special and therefore I define this structure for every
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* kind of file.
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*
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*
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* When reading/writing to a file:
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* - the cgroup to use is file->f_dentry->d_parent->d_fsdata
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* - the 'cftype' of the file is file->f_dentry->d_fsdata
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*/
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#define MAX_CFTYPE_NAME 64
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struct cftype {
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/* By convention, the name should begin with the name of the
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* subsystem, followed by a period */
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char name[MAX_CFTYPE_NAME];
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int private;
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int (*open) (struct inode *inode, struct file *file);
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ssize_t (*read) (struct cgroup *cgrp, struct cftype *cft,
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struct file *file,
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char __user *buf, size_t nbytes, loff_t *ppos);
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/*
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* read_uint() is a shortcut for the common case of returning a
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* single integer. Use it in place of read()
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*/
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u64 (*read_uint) (struct cgroup *cgrp, struct cftype *cft);
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ssize_t (*write) (struct cgroup *cgrp, struct cftype *cft,
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struct file *file,
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const char __user *buf, size_t nbytes, loff_t *ppos);
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/*
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* write_uint() is a shortcut for the common case of accepting
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* a single integer (as parsed by simple_strtoull) from
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* userspace. Use in place of write(); return 0 or error.
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*/
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int (*write_uint) (struct cgroup *cgrp, struct cftype *cft, u64 val);
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int (*release) (struct inode *inode, struct file *file);
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};
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struct cgroup_scanner {
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struct cgroup *cg;
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int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan);
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void (*process_task)(struct task_struct *p,
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struct cgroup_scanner *scan);
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struct ptr_heap *heap;
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};
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/* Add a new file to the given cgroup directory. Should only be
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* called by subsystems from within a populate() method */
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int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
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const struct cftype *cft);
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/* Add a set of new files to the given cgroup directory. Should
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* only be called by subsystems from within a populate() method */
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int cgroup_add_files(struct cgroup *cgrp,
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struct cgroup_subsys *subsys,
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const struct cftype cft[],
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int count);
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int cgroup_is_removed(const struct cgroup *cgrp);
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int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
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int cgroup_task_count(const struct cgroup *cgrp);
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/* Return true if the cgroup is a descendant of the current cgroup */
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int cgroup_is_descendant(const struct cgroup *cgrp);
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/* Control Group subsystem type. See Documentation/cgroups.txt for details */
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struct cgroup_subsys {
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struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss,
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struct cgroup *cgrp);
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void (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
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void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
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int (*can_attach)(struct cgroup_subsys *ss,
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struct cgroup *cgrp, struct task_struct *tsk);
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void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
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struct cgroup *old_cgrp, struct task_struct *tsk);
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void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);
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void (*exit)(struct cgroup_subsys *ss, struct task_struct *task);
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int (*populate)(struct cgroup_subsys *ss,
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struct cgroup *cgrp);
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void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
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void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
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int subsys_id;
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int active;
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int disabled;
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int early_init;
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#define MAX_CGROUP_TYPE_NAMELEN 32
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const char *name;
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/* Protected by RCU */
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struct cgroupfs_root *root;
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struct list_head sibling;
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void *private;
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};
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#define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
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#include <linux/cgroup_subsys.h>
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#undef SUBSYS
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static inline struct cgroup_subsys_state *cgroup_subsys_state(
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struct cgroup *cgrp, int subsys_id)
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{
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return cgrp->subsys[subsys_id];
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}
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static inline struct cgroup_subsys_state *task_subsys_state(
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struct task_struct *task, int subsys_id)
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{
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return rcu_dereference(task->cgroups->subsys[subsys_id]);
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}
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static inline struct cgroup* task_cgroup(struct task_struct *task,
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int subsys_id)
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{
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return task_subsys_state(task, subsys_id)->cgroup;
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}
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int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss);
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/* A cgroup_iter should be treated as an opaque object */
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struct cgroup_iter {
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struct list_head *cg_link;
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struct list_head *task;
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};
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/* To iterate across the tasks in a cgroup:
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*
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* 1) call cgroup_iter_start to intialize an iterator
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*
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* 2) call cgroup_iter_next() to retrieve member tasks until it
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* returns NULL or until you want to end the iteration
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*
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* 3) call cgroup_iter_end() to destroy the iterator.
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*
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* Or, call cgroup_scan_tasks() to iterate through every task in a cpuset.
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* - cgroup_scan_tasks() holds the css_set_lock when calling the test_task()
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* callback, but not while calling the process_task() callback.
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*/
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void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it);
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struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
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struct cgroup_iter *it);
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void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);
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int cgroup_scan_tasks(struct cgroup_scanner *scan);
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int cgroup_attach_task(struct cgroup *, struct task_struct *);
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#else /* !CONFIG_CGROUPS */
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static inline int cgroup_init_early(void) { return 0; }
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static inline int cgroup_init(void) { return 0; }
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static inline void cgroup_init_smp(void) {}
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static inline void cgroup_fork(struct task_struct *p) {}
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static inline void cgroup_fork_callbacks(struct task_struct *p) {}
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static inline void cgroup_post_fork(struct task_struct *p) {}
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static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
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static inline void cgroup_lock(void) {}
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static inline void cgroup_unlock(void) {}
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static inline int cgroupstats_build(struct cgroupstats *stats,
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struct dentry *dentry)
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{
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return -EINVAL;
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}
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#endif /* !CONFIG_CGROUPS */
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#endif /* _LINUX_CGROUP_H */
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