From 8bab8dded67d026c39367bbd5e27d2f6c556c38e Mon Sep 17 00:00:00 2001 From: Paul Menage Date: Fri, 4 Apr 2008 14:29:57 -0700 Subject: [PATCH] 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 Cc: Paul Menage Cc: Balbir Singh Cc: Pavel Emelyanov Cc: KAMEZAWA Hiroyuki Cc: Hugh Dickins Cc: Sudhir Kumar Cc: YAMAMOTO Takashi Cc: David Rientjes Signed-off-by: Li Zefan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/kernel-parameters.txt | 4 +++ include/linux/cgroup.h | 1 + kernel/cgroup.c | 42 +++++++++++++++++++++++++---- 3 files changed, 42 insertions(+), 5 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 4cd1a5da80a4..32e9297ef747 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -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. diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 028ba3b523b1..a6a6035a4e1e 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -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; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 53d86b4b0ce0..62f1a5231fe9 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -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);