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Commit 8bab8dde authored by Paul Menage's avatar Paul Menage Committed by Linus Torvalds
Browse files

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: default avatarBalbir 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: default avatarLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3a143125

Documentation/kernel-parameters.txt

+4 −0
Original line number Diff line number Diff line
@@ -375,6 +375,10 @@ and is between 256 and 4096 characters. It is defined in the file 
	ccw_timeout_log [S390]

			See Documentation/s390/CommonIO for details.



	cgroup_disable= [KNL] Disable a particular controller

			Format: {name of the controller(s) to disable}

				{Currently supported controllers - "memory"}



	checkreqprot	[SELINUX] Set initial checkreqprot flag value.

			Format: { "0" | "1" }

			See security/selinux/Kconfig help text.

include/linux/cgroup.h

+1 −0
Original line number Diff line number Diff line
@@ -256,6 +256,7 @@ struct cgroup_subsys { 
	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;

kernel/cgroup.c

+37 −5
Original line number Diff line number Diff line
@@ -782,7 +782,14 @@ static int parse_cgroupfs_options(char *data, 
		if (!*token)

			return -EINVAL;

		if (!strcmp(token, "all")) {

			opts->subsys_bits = (1 << CGROUP_SUBSYS_COUNT) - 1;

			/* Add all non-disabled subsystems */

			int i;

			opts->subsys_bits = 0;

			for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {

				struct cgroup_subsys *ss = subsys[i];

				if (!ss->disabled)

					opts->subsys_bits |= 1ul << i;

			}

		} else if (!strcmp(token, "noprefix")) {

			set_bit(ROOT_NOPREFIX, &opts->flags);

		} else if (!strncmp(token, "release_agent=", 14)) {
@@ -800,6 +807,7 @@ static int parse_cgroupfs_options(char *data, 
			for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {

				ss = subsys[i];

				if (!strcmp(token, ss->name)) {

					if (!ss->disabled)

						set_bit(i, &opts->subsys_bits);

					break;

				}
@@ -2600,13 +2608,13 @@ static int proc_cgroupstats_show(struct seq_file *m, void *v) 
{

	int i;



	seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\n");

	seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");

	mutex_lock(&cgroup_mutex);

	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {

		struct cgroup_subsys *ss = subsys[i];

		seq_printf(m, "%s\t%lu\t%d\n",

		seq_printf(m, "%s\t%lu\t%d\t%d\n",

			   ss->name, ss->root->subsys_bits,

			   ss->root->number_of_cgroups);

			   ss->root->number_of_cgroups, !ss->disabled);

	}

	mutex_unlock(&cgroup_mutex);

	return 0;
@@ -3010,3 +3018,27 @@ static void cgroup_release_agent(struct work_struct *work) 
	spin_unlock(&release_list_lock);

	mutex_unlock(&cgroup_mutex);

}



static int __init cgroup_disable(char *str)

{

	int i;

	char *token;



	while ((token = strsep(&str, ",")) != NULL) {

		if (!*token)

			continue;



		for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {

			struct cgroup_subsys *ss = subsys[i];



			if (!strcmp(token, ss->name)) {

				ss->disabled = 1;

				printk(KERN_INFO "Disabling %s control group"

					" subsystem\n", ss->name);

				break;

			}

		}

	}

	return 1;

}

__setup("cgroup_disable=", cgroup_disable);