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Date: Wed, 19 Sep 2012 15:43:45 -0700
From: Tejun Heo <tj@...nel.org>
To: linux-kernel@...r.kernel.org,
containers@...ts.linux-foundation.org, cgroups@...r.kernel.org,
lizefan@...wei.com
Cc: peterz@...radead.org, glommer@...allels.com, mhocko@...e.cz,
kay.sievers@...y.org, mzxreary@...inter.de, davej@...hat.com,
ben@...adent.org.uk, pjt@...gle.com, Tejun Heo <tj@...nel.org>
Subject: [PATCH 3/3] cgroup, sched: deprecate cpuacct
Now that cpu serves the same files as cpuacct and using cpuacct
separately from cpu is deprecated, we can deprecate cpuacct. To avoid
disturbing userland which has been co-mounting cpu and cpuacct,
implement some hackery in cgroup core so that cpuacct co-mounting
still works even if cpuacct is disabled.
The goal of this patch is to accelerate disabling and removal of
cpuacct by decoupling kernel-side deprecation from userland changes.
Userland is recommended to do the following.
* If /proc/cgroups lists cpuacct, always co-mount it with cpu under
e.g. /sys/fs/cgroup/cpu.
* Optionally create symlinks for compatibility -
e.g. /sys/fs/cgroup/cpuacct and /sys/fs/cgroup/cpu,cpucct both
pointing to /sys/fs/cgroup/cpu - whether cpuacct exists or not.
This compatibility hack will eventually go away.
Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Glauber Costa <glommer@...allels.com>
Cc: Michal Hocko <mhocko@...e.cz>
Cc: Kay Sievers <kay.sievers@...y.org>
Cc: Lennart Poettering <mzxreary@...inter.de>
Cc: Dave Jones <davej@...hat.com>
Cc: Ben Hutchings <ben@...adent.org.uk>
Cc: Paul Turner <pjt@...gle.com>
---
init/Kconfig | 11 ++++++++++-
kernel/cgroup.c | 41 +++++++++++++++++++++++++++++++++++++++--
kernel/sched/core.c | 2 ++
3 files changed, 51 insertions(+), 3 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index af6c7f8..a13cf8f 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -675,11 +675,20 @@ config PROC_PID_CPUSET
default y
config CGROUP_CPUACCT
- bool "Simple CPU accounting cgroup subsystem"
+ bool "DEPRECATED: Simple CPU accounting cgroup subsystem"
+ default n
help
Provides a simple Resource Controller for monitoring the
total CPU consumed by the tasks in a cgroup.
+ This cgroup subsystem is deprecated. The CPU cgroup
+ subsystem serves the same accounting files and "cpuacct"
+ mount option is ignored if specified with "cpu". As long as
+ userland co-mounts cpu and cpuacct, disabling this
+ controller should be mostly unnoticeable - one notable
+ difference is that /proc/PID/cgroup won't list cpuacct
+ anymore.
+
config RESOURCE_COUNTERS
bool "Resource counters"
help
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 01c11e3..a577f6c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1157,6 +1157,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
unsigned long mask = (unsigned long)-1;
int i;
bool module_pin_failed = false;
+ bool cpuacct_requested = false;
BUG_ON(!mutex_is_locked(&cgroup_mutex));
@@ -1242,8 +1243,13 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
break;
}
- if (i == CGROUP_SUBSYS_COUNT)
+ /* handle deprecated cpuacct specially, see below */
+ if (!strcmp(token, "cpuacct")) {
+ cpuacct_requested = true;
+ one_ss = true;
+ } else if (i == CGROUP_SUBSYS_COUNT) {
return -ENOENT;
+ }
}
/*
@@ -1270,8 +1276,25 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
* this creates some discrepancies in /proc/cgroups and
* /proc/PID/cgroup.
*
+ * Accept and ignore "cpuacct" option if comounted with "cpu" even
+ * when cpuacct itself is disabled to allow quick disabling and
+ * removal of cpuacct. This will be removed eventually.
+ *
* https://lkml.org/lkml/2012/9/13/542
*/
+ if (cpuacct_requested) {
+ bool comounted = false;
+
+#if IS_ENABLED(CONFIG_CGROUP_SCHED)
+ comounted = opts->subsys_bits & (1 << cpu_cgroup_subsys_id);
+#endif
+ if (!comounted) {
+ pr_warning("cgroup: mounting cpuacct separately from cpu is deprecated\n");
+#if !IS_ENABLED(CONFIG_CGROUP_CPUACCT)
+ return -EINVAL;
+#endif
+ }
+ }
#if IS_ENABLED(CONFIG_CGROUP_SCHED) && IS_ENABLED(CONFIG_CGROUP_CPUACCT)
if ((opts->subsys_bits & (1 << cpu_cgroup_subsys_id)) &&
(opts->subsys_bits & (1 << cpuacct_subsys_id)))
@@ -4678,6 +4701,7 @@ const struct file_operations proc_cgroup_operations = {
/* Display information about each subsystem and each hierarchy */
static int proc_cgroupstats_show(struct seq_file *m, void *v)
{
+ struct cgroup_subsys *ss;
int i;
seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
@@ -4688,7 +4712,7 @@ static int proc_cgroupstats_show(struct seq_file *m, void *v)
*/
mutex_lock(&cgroup_mutex);
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
- struct cgroup_subsys *ss = subsys[i];
+ ss = subsys[i];
if (ss == NULL)
continue;
seq_printf(m, "%s\t%d\t%d\t%d\n",
@@ -4696,6 +4720,19 @@ static int proc_cgroupstats_show(struct seq_file *m, void *v)
ss->root->number_of_cgroups, !ss->disabled);
}
mutex_unlock(&cgroup_mutex);
+
+ /*
+ * Fake /proc/cgroups entry for cpuacct to trick userland into
+ * cpu,cpuacct comounts. This is to allow quick disabling and
+ * removal of cpuacct and will be removed eventually.
+ */
+#if IS_ENABLED(CONFIG_CGROUP_SCHED) && !IS_ENABLED(CONFIG_CGROUP_CPUACCT)
+ ss = subsys[cpu_cgroup_subsys_id];
+ if (ss) {
+ seq_printf(m, "cpuacct\t%d\t%d\t%d\n", ss->root->hierarchy_id,
+ ss->root->number_of_cgroups, !ss->disabled);
+ }
+#endif
return 0;
}
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9648671..10176a3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8569,6 +8569,8 @@ struct cgroup_subsys cpu_cgroup_subsys = {
#ifdef CONFIG_CGROUP_CPUACCT
+#warning CONFIG_CGROUP_CPUACCT is deprecated, read the Kconfig help message
+
/*
* CPU accounting code for task groups.
*
--
1.7.7.3
--
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