[-mm] CPU controller statistics (v5)

[Balbir Singh <balbir@linux.vnet.ibm.com>]

From: Balaji Rao <balajirrao@gmail.com>

This is a repost of Balaji's patches at
http://kerneltrap.org/mailarchive/linux-kernel/2008/5/11/1791504
I've made changes to the format exported to user space. I've used
clock_t, since /proc/<pid>/stat uses the same format to export data.

I've run some basic tests to verify that the patches work.

Andrew could you please consider them for inclusion if there are no
objections to this patch. This patch helps fill a void in the controllers
we have w.r.t. statistics

The patch is against the latest git.

Signed-off-by: Balaji Rao <balajirrao@gmail.com>
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>

---
 include/linux/cgroup.h |    1 
 kernel/cgroup.c        |    6 ++
 kernel/sched.c         |  100
 3 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index e155aa7..60a25cb 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -293,6 +293,7 @@ int cgroup_is_descendant(const struct cgroup *cgrp);
 struct cgroup_subsys {
 	struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss,
 						  struct cgroup *cgrp);
+	void (*initialize)(int early);
 	void (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
 	void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
 	int (*can_attach)(struct cgroup_subsys *ss,
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 15ac0e1..77569d7 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2553,6 +2553,9 @@ int __init cgroup_init_early(void)
 
 		if (ss->early_init)
 			cgroup_init_subsys(ss);
+
+		if (ss->initialize)
+			ss->initialize(1);
 	}
 	return 0;
 }
@@ -2577,6 +2580,9 @@ int __init cgroup_init(void)
 		struct cgroup_subsys *ss = subsys[i];
 		if (!ss->early_init)
 			cgroup_init_subsys(ss);
+
+		if (ss->initialize)
+			ss->initialize(0);
 	}
 
 	/* Add init_css_set to the hash table */
diff --git a/kernel/sched.c b/kernel/sched.c
index bfb8ad8..d6df3d3 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -245,11 +245,32 @@ static DEFINE_MUTEX(sched_domains_mutex);
 struct cfs_rq;
 
 static LIST_HEAD(task_groups);
+#ifdef CONFIG_CGROUP_SCHED
+#define CPU_CGROUP_STAT_THRESHOLD (1 << 30)
+enum cpu_cgroup_stat_index {
+	CPU_CGROUP_STAT_UTIME, /* Usertime of the task group */
+	CPU_CGROUP_STAT_STIME, /* Kerneltime of the task group */
+
+	CPU_CGROUP_STAT_NSTATS,
+};
+
+struct cpu_cgroup_stat {
+	struct percpu_counter cpustat[CPU_CGROUP_STAT_NSTATS];
+};
+
+static void __cpu_cgroup_stat_add(struct cpu_cgroup_stat *stat,
+		enum cpu_cgroup_stat_index idx, s64 val)
+{
+	if (stat)
+		percpu_counter_add(&stat->cpustat[idx], val);
+}
+#endif
 
 /* task group related information */
 struct task_group {
 #ifdef CONFIG_CGROUP_SCHED
 	struct cgroup_subsys_state css;
+	struct cpu_cgroup_stat *stat;
 #endif
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
@@ -3885,6 +3906,16 @@ void account_user_time(struct task_struct *p, cputime_t cputime)
 		cpustat->nice = cputime64_add(cpustat->nice, tmp);
 	else
 		cpustat->user = cputime64_add(cpustat->user, tmp);
+
+       /* Charge the task's group */
+#ifdef CONFIG_CGROUP_SCHED
+	{
+		struct task_group *tg;
+		tg = task_group(p);
+		__cpu_cgroup_stat_add(tg->stat, CPU_CGROUP_STAT_UTIME,
+				cputime_to_msecs(cputime) * NSEC_PER_MSEC);
+	}
+#endif
 }
 
 /*
@@ -3942,8 +3973,17 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
 		cpustat->irq = cputime64_add(cpustat->irq, tmp);
 	else if (softirq_count())
 		cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
-	else if (p != rq->idle)
+	else if (p != rq->idle) {
 		cpustat->system = cputime64_add(cpustat->system, tmp);
+#ifdef CONFIG_CGROUP_SCHED
+		{
+			struct task_group *tg;
+			tg = task_group(p);
+			__cpu_cgroup_stat_add(tg->stat, CPU_CGROUP_STAT_STIME,
+				cputime_to_msecs(cputime) * NSEC_PER_MSEC);
+		}
+#endif
+	}
 	else if (atomic_read(&rq->nr_iowait) > 0)
 		cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
 	else
@@ -8325,6 +8365,24 @@ unsigned long sched_group_shares(struct task_group *tg)
 }
 #endif
 
+static s64 cpu_cgroup_read_stat(struct cpu_cgroup_stat *stat,
+		enum cpu_cgroup_stat_index idx)
+{
+	if (stat)
+		return nsec_to_clock_t(
+				percpu_counter_read(&stat->cpustat[idx]));
+
+	return 0;
+}
+
+static const struct cpu_cgroup_stat_desc {
+	const char *msg;
+	u64 unit;
+} cpu_cgroup_stat_desc[] = {
+	[CPU_CGROUP_STAT_UTIME] = { "utime", 1, },
+	[CPU_CGROUP_STAT_STIME] = { "stime", 1, },
+};
+
 #ifdef CONFIG_RT_GROUP_SCHED
 /*
  * Ensure that the real time constraints are schedulable.
@@ -8551,10 +8609,41 @@ static inline struct task_group *cgroup_tg(struct cgroup *cgrp)
 			    struct task_group, css);
 }
 
+static int cpu_cgroup_stats_show(struct cgroup *cgrp, struct cftype *cft,
+		struct cgroup_map_cb *cb)
+{
+	struct task_group *tg = cgroup_tg(cgrp);
+	struct cpu_cgroup_stat *stat = tg->stat;
+	int i;
+	for (i = 0; i < CPU_CGROUP_STAT_NSTATS; i++) {
+		s64 val;
+		val = cpu_cgroup_read_stat(stat, i);
+		val *= cpu_cgroup_stat_desc[i].unit;
+		cb->fill(cb, cpu_cgroup_stat_desc[i].msg, val);
+	}
+	return 0;
+}
+
+static void cpu_cgroup_initialize(int early)
+{
+	int i;
+	struct cpu_cgroup_stat *stat;
+
+	if (!early) {
+		stat = kmalloc(sizeof(struct cpu_cgroup_stat)
+				, GFP_KERNEL);
+		for (i = 0; i < CPU_CGROUP_STAT_NSTATS; i++)
+			percpu_counter_init(
+					&stat->cpustat[i], 0);
+		init_task_group.stat = stat;
+	}
+}
+
 static struct cgroup_subsys_state *
 cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
 {
 	struct task_group *tg, *parent;
+	int i;
 
 	if (!cgrp->parent) {
 		/* This is early initialization for the top cgroup */
@@ -8567,6 +8656,10 @@ cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
 	if (IS_ERR(tg))
 		return ERR_PTR(-ENOMEM);
 
+	tg->stat = kmalloc(sizeof(struct cpu_cgroup_stat), GFP_KERNEL);
+	for (i = 0; i < CPU_CGROUP_STAT_NSTATS; i++)
+		percpu_counter_init(&tg->stat->cpustat[i], 0);
+
 	/* Bind the cgroup to task_group object we just created */
 	tg->css.cgroup = cgrp;
 
@@ -8664,6 +8757,10 @@ static struct cftype cpu_files[] = {
 		.write_u64 = cpu_rt_period_write_uint,
 	},
 #endif
+	{
+		.name = "stat",
+		.read_map = cpu_cgroup_stats_show,
+	},
 };
 
 static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)
@@ -8673,6 +8770,7 @@ static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)
 
 struct cgroup_subsys cpu_cgroup_subsys = {
 	.name		= "cpu",
+	.initialize	= cpu_cgroup_initialize,
 	.create		= cpu_cgroup_create,
 	.destroy	= cpu_cgroup_destroy,
 	.can_attach	= cpu_cgroup_can_attach,

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL