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cgroups: add cgroup support for enabling controllers at boot time

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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>
This commit is contained in:
Paul Menage 2008-04-04 14:29:57 -07:00 committed by Linus Torvalds
parent 3a143125dd
commit 8bab8dded6
3 changed files with 42 additions and 5 deletions
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4
Documentation/kernel-parameters.txt
View file

@ -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.

1
include/linux/cgroup.h
View file

@ -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;

42
kernel/cgroup.c
View file

@ -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)) {
@ -800,7 +807,8 @@ static int parse_cgroupfs_options(char *data,
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
ss = subsys[i];
if (!strcmp(token, ss->name)) {
set_bit(i, &opts->subsys_bits);
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);