This patch demonstrates how a resource controller can work with rcfs.

The controller counts the total CPU time used by all processes in a
resource container, during the time that they're members of the
container.

Written by Paul Menage. Adapted to work with rcfs by Srivatsa.


Signed-off-by : Paul Menage <menage@google.com>
Signed-off-by : Srivatsa Vaddagiri <vatsa@in.ibm.com>




diff -puN /dev/null include/linux/cpu_acct.h
--- /dev/null	2006-02-25 03:06:56.000000000 +0530
+++ linux-2.6.20-vatsa/include/linux/cpu_acct.h	2007-03-01 16:53:39.000000000 +0530
@@ -0,0 +1,14 @@
+
+#ifndef _LINUX_CPU_ACCT_H
+#define _LINUX_CPU_ACCT_H
+
+#include <linux/rcfs.h>
+#include <asm/cputime.h>
+
+#ifdef CONFIG_RC_CPUACCT
+extern void cpuacct_charge(struct task_struct *, cputime_t cputime);
+#else
+static void inline cpuacct_charge(struct task_struct *p, cputime_t cputime) {}
+#endif
+
+#endif
diff -puN init/Kconfig~cpu_acct init/Kconfig
--- linux-2.6.20/init/Kconfig~cpu_acct	2007-03-01 16:53:39.000000000 +0530
+++ linux-2.6.20-vatsa/init/Kconfig	2007-03-01 16:53:39.000000000 +0530
@@ -291,6 +291,13 @@ config SYSFS_DEPRECATED
 	  If you are using a distro that was released in 2006 or later,
 	  it should be safe to say N here.
 
+config RC_CPUACCT
+	bool "Simple CPU accounting container subsystem"
+	select RCFS
+	help
+	  Provides a simple Resource Controller for monitoring the
+	  total CPU consumed by the tasks in a container
+
 config RELAY
 	bool "Kernel->user space relay support (formerly relayfs)"
 	help
diff -puN /dev/null kernel/cpu_acct.c
--- /dev/null	2006-02-25 03:06:56.000000000 +0530
+++ linux-2.6.20-vatsa/kernel/cpu_acct.c	2007-03-01 16:53:39.000000000 +0530
@@ -0,0 +1,221 @@
+/*
+ * kernel/cpu_acct.c - CPU accounting container subsystem
+ *
+ * Copyright (C) Google Inc, 2006
+ *
+ * Developed by Paul Menage (menage@google.com) and Balbir Singh
+ * (balbir@in.ibm.com)
+ *
+ */
+
+/*
+ * Container subsystem for reporting total CPU usage of tasks in a
+ * container, along with percentage load over a time interval
+ */
+
+#include <linux/module.h>
+#include <linux/nsproxy.h>
+#include <linux/rcfs.h>
+#include <linux/fs.h>
+#include <asm/div64.h>
+
+struct cpuacct {
+	spinlock_t lock;
+	/* total time used by this class */
+	cputime64_t time;
+
+	/* time when next load calculation occurs */
+	u64 next_interval_check;
+
+	/* time used in current period */
+	cputime64_t current_interval_time;
+
+	/* time used in last period */
+	cputime64_t last_interval_time;
+};
+
+static struct rc_subsys cpuacct_subsys;
+
+static inline struct cpuacct *nsproxy_ca(struct nsproxy *ns)
+{
+	if (!ns)
+		return NULL;
+
+	return ns->ctlr_data[cpuacct_subsys.subsys_id];
+}
+
+static inline struct cpuacct *task_ca(struct task_struct *task)
+{
+	return nsproxy_ca(task->nsproxy);
+}
+
+#define INTERVAL (HZ * 10)
+
+static inline u64 next_interval_boundary(u64 now) {
+	/* calculate the next interval boundary beyond the
+	 * current time */
+	do_div(now, INTERVAL);
+	return (now + 1) * INTERVAL;
+}
+
+static int cpuacct_create(struct rc_subsys *ss, struct nsproxy *ns,
+					struct nsproxy *parent)
+{
+	struct cpuacct *ca;
+
+	if (parent && (parent != &init_nsproxy))
+		return -EINVAL;
+
+	ca = kzalloc(sizeof(*ca), GFP_KERNEL);
+	if (!ca)
+		return -ENOMEM;
+	spin_lock_init(&ca->lock);
+	ca->next_interval_check = next_interval_boundary(get_jiffies_64());
+	ns->ctlr_data[cpuacct_subsys.subsys_id] = ca;
+	return 0;
+}
+
+static void cpuacct_destroy(struct rc_subsys *ss, struct nsproxy *ns)
+{
+	kfree(nsproxy_ca(ns));
+}
+
+/* Lazily update the load calculation if necessary. Called with ca locked */
+static void cpuusage_update(struct cpuacct *ca)
+{
+	u64 now = get_jiffies_64();
+	/* If we're not due for an update, return */
+	if (ca->next_interval_check > now)
+		return;
+
+	if (ca->next_interval_check <= (now - INTERVAL)) {
+		/* If it's been more than an interval since the last
+		 * check, then catch up - the last interval must have
+		 * been zero load */
+		ca->last_interval_time = 0;
+		ca->next_interval_check = next_interval_boundary(now);
+	} else {
+		/* If a steal takes the last interval time negative,
+		 * then we just ignore it */
+		if ((s64)ca->current_interval_time > 0) {
+			ca->last_interval_time = ca->current_interval_time;
+		} else {
+			ca->last_interval_time = 0;
+		}
+		ca->next_interval_check += INTERVAL;
+	}
+	ca->current_interval_time = 0;
+}
+
+static ssize_t cpuusage_read(struct nsproxy *ns,
+			     struct cftype *cft,
+			     struct file *file,
+			     char __user *buf,
+			     size_t nbytes, loff_t *ppos)
+{
+	struct cpuacct *ca = nsproxy_ca(ns);
+	u64 time;
+	char usagebuf[64];
+	char *s = usagebuf;
+
+	spin_lock_irq(&ca->lock);
+	cpuusage_update(ca);
+	time = cputime64_to_jiffies64(ca->time);
+	spin_unlock_irq(&ca->lock);
+
+	/* Convert 64-bit jiffies to seconds */
+	time *= 1000;
+	do_div(time, HZ);
+	s += sprintf(s, "%llu", (unsigned long long) time);
+
+	return simple_read_from_buffer(buf, nbytes, ppos, usagebuf, s - usagebuf);
+}
+
+static ssize_t load_read(struct nsproxy *ns,
+			 struct cftype *cft,
+			 struct file *file,
+			 char __user *buf,
+			 size_t nbytes, loff_t *ppos)
+{
+	struct cpuacct *ca = nsproxy_ca(ns);
+	u64 time;
+	char usagebuf[64];
+	char *s = usagebuf;
+
+	/* Find the time used in the previous interval */
+	spin_lock_irq(&ca->lock);
+	cpuusage_update(ca);
+	time = cputime64_to_jiffies64(ca->last_interval_time);
+	spin_unlock_irq(&ca->lock);
+
+	/* Convert time to a percentage, to give the load in the
+	 * previous period */
+	time *= 100;
+	do_div(time, INTERVAL);
+
+	s += sprintf(s, "%llu", (unsigned long long) time);
+
+	return simple_read_from_buffer(buf, nbytes, ppos, usagebuf, s - usagebuf);
+}
+
+static struct cftype cft_usage = {
+	.name = "cpuacct.usage",
+	.read = cpuusage_read,
+};
+
+static struct cftype cft_load = {
+	.name = "cpuacct.load",
+	.read = load_read,
+};
+
+static int cpuacct_populate(struct rc_subsys *ss,
+			    struct dentry *d)
+{
+	int err;
+
+	if ((err = rcfs_add_file(d, &cft_usage)))
+		return err;
+	if ((err = rcfs_add_file(d, &cft_load)))
+		return err;
+
+	return 0;
+}
+
+
+void cpuacct_charge(struct task_struct *task, cputime_t cputime)
+{
+
+	struct cpuacct *ca;
+	unsigned long flags;
+
+	if (!cpuacct_subsys.active)
+		return;
+	rcu_read_lock();
+	ca = task_ca(task);
+	if (ca) {
+		spin_lock_irqsave(&ca->lock, flags);
+		cpuusage_update(ca);
+		ca->time = cputime64_add(ca->time, cputime);
+		ca->current_interval_time =
+			cputime64_add(ca->current_interval_time, cputime);
+		spin_unlock_irqrestore(&ca->lock, flags);
+	}
+	rcu_read_unlock();
+}
+
+static struct rc_subsys cpuacct_subsys = {
+	.name = "cpuacct",
+	.create = cpuacct_create,
+	.destroy = cpuacct_destroy,
+	.populate = cpuacct_populate,
+	.subsys_id = -1,
+};
+
+
+int __init init_cpuacct(void)
+{
+	int id = rc_register_subsys(&cpuacct_subsys);
+	return id < 0 ? id : 0;
+}
+
+module_init(init_cpuacct)
diff -puN kernel/Makefile~cpu_acct kernel/Makefile
--- linux-2.6.20/kernel/Makefile~cpu_acct	2007-03-01 16:53:39.000000000 +0530
+++ linux-2.6.20-vatsa/kernel/Makefile	2007-03-01 16:53:39.000000000 +0530
@@ -36,6 +36,7 @@ obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
 obj-$(CONFIG_KEXEC) += kexec.o
 obj-$(CONFIG_COMPAT) += compat.o
 obj-$(CONFIG_CPUSETS) += cpuset.o
+obj-$(CONFIG_RC_CPUACCT) += cpu_acct.o
 obj-$(CONFIG_IKCONFIG) += configs.o
 obj-$(CONFIG_STOP_MACHINE) += stop_machine.o
 obj-$(CONFIG_AUDIT) += audit.o auditfilter.o
diff -puN kernel/sched.c~cpu_acct kernel/sched.c
--- linux-2.6.20/kernel/sched.c~cpu_acct	2007-03-01 16:53:39.000000000 +0530
+++ linux-2.6.20-vatsa/kernel/sched.c	2007-03-01 16:53:39.000000000 +0530
@@ -52,6 +52,7 @@
 #include <linux/tsacct_kern.h>
 #include <linux/kprobes.h>
 #include <linux/delayacct.h>
+#include <linux/cpu_acct.h>
 #include <asm/tlb.h>
 
 #include <asm/unistd.h>
@@ -3066,9 +3067,13 @@ void account_user_time(struct task_struc
 {
 	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
 	cputime64_t tmp;
+	struct rq *rq = this_rq();
 
 	p->utime = cputime_add(p->utime, cputime);
 
+	if (p != rq->idle)
+		cpuacct_charge(p, cputime);
+
 	/* Add user time to cpustat. */
 	tmp = cputime_to_cputime64(cputime);
 	if (TASK_NICE(p) > 0)
@@ -3098,9 +3103,10 @@ void account_system_time(struct task_str
 		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);
-	else if (atomic_read(&rq->nr_iowait) > 0)
+		cpuacct_charge(p, cputime);
+	} else if (atomic_read(&rq->nr_iowait) > 0)
 		cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
 	else
 		cpustat->idle = cputime64_add(cpustat->idle, tmp);
@@ -3125,8 +3131,10 @@ void account_steal_time(struct task_stru
 			cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
 		else
 			cpustat->idle = cputime64_add(cpustat->idle, tmp);
-	} else
+	} else {
 		cpustat->steal = cputime64_add(cpustat->steal, tmp);
+		cpuacct_charge(p, -tmp);
+	}
 }
 
 static void task_running_tick(struct rq *rq, struct task_struct *p)
_

-- 
Regards,
vatsa
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