[v2,1/3] scheduler: cpuacct: Enable platform hooks to track cpuusage for CPU frequencies

Commit Message

Mike Chan May 20, 2010, 6:42 p.m. UTC

None

Patch

diff --git a/Documentation/cgroups/cpuacct.txt b/Documentation/cgroups/cpuacct.txt
index 8b93094..600d2d0 100644
--- a/Documentation/cgroups/cpuacct.txt
+++ b/Documentation/cgroups/cpuacct.txt
@@ -40,6 +40,10 @@  system: Time spent by tasks of the cgroup in kernel mode.
 
 user and system are in USER_HZ unit.
 
+cpuacct.cpufreq file gives CPU time (in nanoseconds) spent at each CPU
+frequency. Platform hooks must be implemented inorder to properly track
+time at each CPU frequency.
+
 cpuacct controller uses percpu_counter interface to collect user and
 system times. This has two side effects:
 
diff --git a/include/linux/cpuacct.h b/include/linux/cpuacct.h
new file mode 100644
index 0000000..6205d29
--- /dev/null
+++ b/include/linux/cpuacct.h
@@ -0,0 +1,41 @@ 
+/* include/linux/cpuacct.h
+ *
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _CPUACCT_H_
+#define _CPUACCT_H_
+
+#ifdef CONFIG_CGROUP_CPUACCT
+
+#include <linux/cgroup.h>
+
+/*
+ * Platform specific CPU frequency hooks for cpuacct. These functions are
+ * called from the scheduler.
+ */
+struct cpuacct_charge_calls {
+	/*
+	 * Platforms can take advantage of this data and use
+	 * per-cpu allocations if necessary.
+	 */
+	void (*init) (void **cpuacct_data);
+	void (*charge) (void *cpuacct_data,  u64 cputime, unsigned int cpu);
+	void (*show) (void *cpuacct_data, struct cgroup_map_cb *cb);
+};
+
+int cpuacct_charge_register(struct cpuacct_charge_calls *fn);
+
+#endif /* CONFIG_CGROUPS */
+
+#endif /* _CPUACCT_H_ */
diff --git a/kernel/cgroup_cpuaccount.c b/kernel/cgroup_cpuaccount.c
index 0ad356a..11799a7 100644
--- a/kernel/cgroup_cpuaccount.c
+++ b/kernel/cgroup_cpuaccount.c
@@ -7,6 +7,7 @@ 
 #include <linux/slab.h>
 #include <linux/seq_file.h>
 #include <linux/err.h>
+#include <linux/cpuacct.h>
 
 #include <asm/cputime.h>
 
@@ -26,8 +27,30 @@  struct cpuacct {
 	u64 __percpu *cpuusage;
 	struct percpu_counter cpustat[CPUACCT_STAT_NSTATS];
 	struct cpuacct *parent;
+	struct cpuacct_charge_calls *cpufreq_fn;
+	void *cpuacct_data;
 };
 
+static struct cpuacct *cpuacct_root;
+
+/* Default calls for cpufreq accounting */
+static struct cpuacct_charge_calls *cpuacct_cpufreq;
+int cpuacct_charge_register(struct cpuacct_charge_calls *fn)
+{
+	cpuacct_cpufreq = fn;
+
+	/*
+	 * Root node is created before platform can register callbacks,
+	 * initalize here.
+	 */
+	if (cpuacct_root && fn) {
+		cpuacct_root->cpufreq_fn = fn;
+		if (fn->init)
+			fn->init(&cpuacct_root->cpuacct_data);
+	}
+	return 0;
+}
+
 struct cgroup_subsys cpuacct_subsys;
 
 /* return cpu accounting group corresponding to this container */
@@ -62,8 +85,16 @@  static struct cgroup_subsys_state *cpuacct_create(
 		if (percpu_counter_init(&ca->cpustat[i], 0))
 			goto out_free_counters;
 
+	ca->cpufreq_fn = cpuacct_cpufreq;
+
+	/* If available, have platform code initalize cpu frequency data */
+	if (ca->cpufreq_fn && ca->cpufreq_fn->init)
+		ca->cpufreq_fn->init(&ca->cpuacct_data);
+
 	if (cgrp->parent)
 		ca->parent = cgroup_ca(cgrp->parent);
+	else
+		cpuacct_root = ca;
 
 	return &ca->css;
 
@@ -191,6 +222,16 @@  static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft,
 	return 0;
 }
 
+static int cpuacct_cpufreq_show(struct cgroup *cgrp, struct cftype *cft,
+		struct cgroup_map_cb *cb)
+{
+	struct cpuacct *ca = cgroup_ca(cgrp);
+	if (ca->cpufreq_fn && ca->cpufreq_fn->show)
+		ca->cpufreq_fn->show(ca->cpuacct_data, cb);
+
+	return 0;
+}
+
 static struct cftype files[] = {
 	{
 		.name = "usage",
@@ -205,6 +246,10 @@  static struct cftype files[] = {
 		.name = "stat",
 		.read_map = cpuacct_stats_show,
 	},
+	{
+		.name =  "cpufreq",
+		.read_map = cpuacct_cpufreq_show,
+	},
 };
 
 static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
@@ -234,6 +279,10 @@  void cpuacct_charge(struct task_struct *tsk, u64 cputime)
 	for (; ca; ca = ca->parent) {
 		u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
 		*cpuusage += cputime;
+
+		/* Call back into platform code to account for CPU speeds */
+		if (ca->cpufreq_fn && ca->cpufreq_fn->charge)
+			ca->cpufreq_fn->charge(ca->cpuacct_data, cputime, cpu);
 	}
 
 	rcu_read_unlock();