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Message-ID: <20090317062155.GE3314@in.ibm.com>
Date: Tue, 17 Mar 2009 11:51:55 +0530
From: Bharata B Rao <bharata@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: Balaji Rao <balajirrao@...il.com>,
Dhaval Giani <dhaval@...ux.vnet.ibm.com>,
Balbir Singh <balbir@...ux.vnet.ibm.com>,
Li Zefan <lizf@...fujitsu.com>,
Paul Menage <menage@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Ingo Molnar <mingo@...e.hu>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: [PATCH -tip] cpuacct: per-cgroup utime/stime statistics - v3
Hi,
Here is the next version of the cpuacct stime/utime statistics patch.
Ingo, Could you please consider this for -tip ?
Changes for v3:
- Fix a small race in the cpuacct hierarchy walk.
v2:
http://lkml.org/lkml/2009/3/12/170
v1:
http://lkml.org/lkml/2009/3/10/150
--
cpuacct: Add stime and utime statistics
Add per-cgroup cpuacct controller statistics like the system and user
time consumed by the group of tasks.
Signed-off-by: Bharata B Rao <bharata@...ux.vnet.ibm.com>
Signed-off-by: Balaji Rao <balajirrao@...il.com>
---
Documentation/cgroups/cpuacct.txt | 17 +++++++
kernel/sched.c | 92 +++++++++++++++++++++++++++++++++++---
2 files changed, 103 insertions(+), 6 deletions(-)
--- a/Documentation/cgroups/cpuacct.txt
+++ b/Documentation/cgroups/cpuacct.txt
@@ -30,3 +30,20 @@ The above steps create a new group g1 an
process (bash) into it. CPU time consumed by this bash and its children
can be obtained from g1/cpuacct.usage and the same is accumulated in
/cgroups/cpuacct.usage also.
+
+cpuacct.stat file lists a few statistics which further divide the
+CPU time obtained by the cgroup into user and system times. Currently
+the following statistics are supported:
+
+utime: Time spent by tasks of the cgroup in user mode.
+stime: Time spent by tasks of the cgroup in kernel mode.
+
+utime and stime are in USER_HZ unit.
+
+cpuacct controller uses percpu_counter interface to collect utime and
+stime. This causes two side effects:
+
+- It is theoritically possible to see wrong values for stime and utime.
+ This is because percpu_counter_read() on 32bit systems is broken.
+- It is possible to see slightly outdated values for stime and utime
+ due to the batch processing nature of percpu_counter.
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1442,10 +1442,22 @@ iter_move_one_task(struct rq *this_rq, i
struct rq_iterator *iterator);
#endif
+/* Time spent by the tasks of the cpu accounting group executing in ... */
+enum cpuacct_stat_index {
+ CPUACCT_STAT_UTIME, /* ... user mode */
+ CPUACCT_STAT_STIME, /* ... kernel mode */
+
+ CPUACCT_STAT_NSTATS,
+};
+
#ifdef CONFIG_CGROUP_CPUACCT
static void cpuacct_charge(struct task_struct *tsk, u64 cputime);
+static void cpuacct_update_stats(struct task_struct *tsk,
+ enum cpuacct_stat_index idx, cputime_t val);
#else
static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {}
+static inline void cpuacct_update_stats(struct task_struct *tsk,
+ enum cpuacct_stat_index idx, cputime_t val) {}
#endif
static inline void inc_cpu_load(struct rq *rq, unsigned long load)
@@ -4387,6 +4399,8 @@ void account_user_time(struct task_struc
cpustat->nice = cputime64_add(cpustat->nice, tmp);
else
cpustat->user = cputime64_add(cpustat->user, tmp);
+
+ cpuacct_update_stats(p, CPUACCT_STAT_UTIME, cputime);
/* Account for user time used */
acct_update_integrals(p);
}
@@ -4448,6 +4462,8 @@ void account_system_time(struct task_str
else
cpustat->system = cputime64_add(cpustat->system, tmp);
+ cpuacct_update_stats(p, CPUACCT_STAT_STIME, cputime);
+
/* Account for system time used */
acct_update_integrals(p);
}
@@ -9727,6 +9743,7 @@ struct cpuacct {
struct cgroup_subsys_state css;
/* cpuusage holds pointer to a u64-type object on every cpu */
u64 *cpuusage;
+ struct percpu_counter cpustat[CPUACCT_STAT_NSTATS];
struct cpuacct *parent;
};
@@ -9751,20 +9768,33 @@ static struct cgroup_subsys_state *cpuac
struct cgroup_subsys *ss, struct cgroup *cgrp)
{
struct cpuacct *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
+ int i;
if (!ca)
- return ERR_PTR(-ENOMEM);
+ goto out;
ca->cpuusage = alloc_percpu(u64);
- if (!ca->cpuusage) {
- kfree(ca);
- return ERR_PTR(-ENOMEM);
- }
+ if (!ca->cpuusage)
+ goto out_free_ca;
+
+ for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
+ if (percpu_counter_init(&ca->cpustat[i], 0))
+ goto out_free_counters;
if (cgrp->parent)
ca->parent = cgroup_ca(cgrp->parent);
return &ca->css;
+
+out_free_counters:
+ i--;
+ while (i-- >= 0)
+ percpu_counter_destroy(&ca->cpustat[i]);
+ free_percpu(ca->cpuusage);
+out_free_ca:
+ kfree(ca);
+out:
+ return ERR_PTR(-ENOMEM);
}
/* destroy an existing cpu accounting group */
@@ -9772,7 +9802,10 @@ static void
cpuacct_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
{
struct cpuacct *ca = cgroup_ca(cgrp);
+ int i;
+ for (i = 0; i < CPUACCT_STAT_NSTATS; i++)
+ percpu_counter_destroy(&ca->cpustat[i]);
free_percpu(ca->cpuusage);
kfree(ca);
}
@@ -9859,6 +9892,25 @@ static int cpuacct_percpu_seq_read(struc
return 0;
}
+static const char *cpuacct_stat_desc[] = {
+ [CPUACCT_STAT_UTIME] = "utime",
+ [CPUACCT_STAT_STIME] = "stime",
+};
+
+static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft,
+ struct cgroup_map_cb *cb)
+{
+ struct cpuacct *ca = cgroup_ca(cgrp);
+ int i;
+
+ for (i = 0; i < CPUACCT_STAT_NSTATS; i++) {
+ s64 val = percpu_counter_read(&ca->cpustat[i]);
+ val = cputime_to_clock_t(val);
+ cb->fill(cb, cpuacct_stat_desc[i], val);
+ }
+ return 0;
+}
+
static struct cftype files[] = {
{
.name = "usage",
@@ -9869,7 +9921,10 @@ static struct cftype files[] = {
.name = "usage_percpu",
.read_seq_string = cpuacct_percpu_seq_read,
},
-
+ {
+ .name = "stat",
+ .read_map = cpuacct_stats_show,
+ },
};
static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
@@ -9908,6 +9963,31 @@ static void cpuacct_charge(struct task_s
rcu_read_unlock();
}
+/*
+ * Charge the system/user time to the task's accounting group.
+ */
+static void cpuacct_update_stats(struct task_struct *tsk,
+ enum cpuacct_stat_index idx, cputime_t val)
+{
+ struct cpuacct *ca;
+
+ if (unlikely(!cpuacct_subsys.active))
+ return;
+
+ /*
+ * rcu_read_lock() protects ca thus making sure that hierarchy
+ * walk is safe.
+ */
+ rcu_read_lock();
+ ca = task_ca(tsk);
+
+ do {
+ percpu_counter_add(&ca->cpustat[idx], val);
+ ca = ca->parent;
+ } while (ca);
+ rcu_read_unlock();
+}
+
struct cgroup_subsys cpuacct_subsys = {
.name = "cpuacct",
.create = cpuacct_create,
--
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