Task Control Groups: example CPU accounting subsystem

This example demonstrates how to use the generic cgroup subsystem for a
simple resource tracker that counts, for the processes in a cgroup, the
total CPU time used and the %CPU used in the last complete 10 second interval.

Portions contributed by Balbir Singh <balbir@in.ibm.com>

Signed-off-by: Paul Menage <menage@google.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
index b152b51..a568b87 100644 (file)
--- a/include/linux/cgroup_subsys.h
+++ b/include/linux/cgroup_subsys.h
@@ -13,4 +13,10 @@ SUBSYS(cpuset)
 
 /* */
 
+#ifdef CONFIG_CGROUP_CPUACCT
+SUBSYS(cpuacct)
+#endif
+
+/* */
+
 /* */

diff --git a/include/linux/cpu_acct.h b/include/linux/cpu_acct.h
new file mode 100644 (file)
index 0000000..6b5fd8a
--- /dev/null
+++ b/include/linux/cpu_acct.h
@@ -0,0 +1,14 @@
+
+#ifndef _LINUX_CPU_ACCT_H
+#define _LINUX_CPU_ACCT_H
+
+#include <linux/cgroup.h>
+#include <asm/cputime.h>
+
+#ifdef CONFIG_CGROUP_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 --git a/init/Kconfig b/init/Kconfig
index 18b1abc..b59a0a9 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -335,6 +335,13 @@ config PROC_PID_CPUSET
        depends on CPUSETS
        default y
 
+config CGROUP_CPUACCT
+       bool "Simple CPU accounting cgroup subsystem"
+       depends on CGROUPS
+       help
+         Provides a simple Resource Controller for monitoring the
+         total CPU consumed by the tasks in a cgroup
+
 config RELAY
        bool "Kernel->user space relay support (formerly relayfs)"
        help

diff --git a/kernel/Makefile b/kernel/Makefile
index ea8c8a1..48a7fae 100644 (file)
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_KEXEC) += kexec.o
 obj-$(CONFIG_COMPAT) += compat.o
 obj-$(CONFIG_CGROUPS) += cgroup.o
 obj-$(CONFIG_CPUSETS) += cpuset.o
+obj-$(CONFIG_CGROUP_CPUACCT) += cpu_acct.o
 obj-$(CONFIG_IKCONFIG) += configs.o
 obj-$(CONFIG_STOP_MACHINE) += stop_machine.o
 obj-$(CONFIG_AUDIT) += audit.o auditfilter.o

diff --git a/kernel/cpu_acct.c b/kernel/cpu_acct.c
new file mode 100644 (file)
index 0000000..731e47e
--- /dev/null
+++ b/kernel/cpu_acct.c
@@ -0,0 +1,186 @@
+/*
+ * kernel/cpu_acct.c - CPU accounting cgroup subsystem
+ *
+ * Copyright (C) Google Inc, 2006
+ *
+ * Developed by Paul Menage (menage@google.com) and Balbir Singh
+ * (balbir@in.ibm.com)
+ *
+ */
+
+/*
+ * Example cgroup subsystem for reporting total CPU usage of tasks in a
+ * cgroup, along with percentage load over a time interval
+ */
+
+#include <linux/module.h>
+#include <linux/cgroup.h>
+#include <linux/fs.h>
+#include <linux/rcupdate.h>
+
+#include <asm/div64.h>
+
+struct cpuacct {
+       struct cgroup_subsys_state css;
+       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;
+};
+
+struct cgroup_subsys cpuacct_subsys;
+
+static inline struct cpuacct *cgroup_ca(struct cgroup *cont)
+{
+       return container_of(cgroup_subsys_state(cont, cpuacct_subsys_id),
+                           struct cpuacct, css);
+}
+
+static inline struct cpuacct *task_ca(struct task_struct *task)
+{
+       return container_of(task_subsys_state(task, cpuacct_subsys_id),
+                           struct cpuacct, css);
+}
+
+#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 struct cgroup_subsys_state *cpuacct_create(
+       struct cgroup_subsys *ss, struct cgroup *cont)
+{
+       struct cpuacct *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
+
+       if (!ca)
+               return ERR_PTR(-ENOMEM);
+       spin_lock_init(&ca->lock);
+       ca->next_interval_check = next_interval_boundary(get_jiffies_64());
+       return &ca->css;
+}
+
+static void cpuacct_destroy(struct cgroup_subsys *ss,
+                           struct cgroup *cont)
+{
+       kfree(cgroup_ca(cont));
+}
+
+/* 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 u64 cpuusage_read(struct cgroup *cont, struct cftype *cft)
+{
+       struct cpuacct *ca = cgroup_ca(cont);
+       u64 time;
+
+       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);
+       return time;
+}
+
+static u64 load_read(struct cgroup *cont, struct cftype *cft)
+{
+       struct cpuacct *ca = cgroup_ca(cont);
+       u64 time;
+
+       /* 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);
+
+       return time;
+}
+
+static struct cftype files[] = {
+       {
+               .name = "usage",
+               .read_uint = cpuusage_read,
+       },
+       {
+               .name = "load",
+               .read_uint = load_read,
+       }
+};
+
+static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+       return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
+}
+
+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();
+}
+
+struct cgroup_subsys cpuacct_subsys = {
+       .name = "cpuacct",
+       .create = cpuacct_create,
+       .destroy = cpuacct_destroy,
+       .populate = cpuacct_populate,
+       .subsys_id = cpuacct_subsys_id,
+};

diff --git a/kernel/sched.c b/kernel/sched.c
index ed90be4..72a2a16 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -51,6 +51,7 @@
 #include <linux/cpu.h>
 #include <linux/cpuset.h>
 #include <linux/percpu.h>
+#include <linux/cpu_acct.h>
 #include <linux/kthread.h>
 #include <linux/seq_file.h>
 #include <linux/sysctl.h>
@@ -3307,9 +3308,13 @@ void account_user_time(struct task_struct *p, cputime_t cputime)
 {
        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)
@@ -3374,9 +3379,10 @@ 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);
-       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);
@@ -3412,8 +3418,10 @@ void account_steal_time(struct task_struct *p, cputime_t steal)
                        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);
+       }
 }
 
 /*