summaryrefslogtreecommitdiffstats
path: root/kernel/sched/cpuacct.c
blob: dd7cbb55bbf2c98591dd31603790676136eafd82 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
#include <linux/cgroup.h>
#include <linux/slab.h>
#include <linux/percpu.h>
#include <linux/spinlock.h>
#include <linux/cpumask.h>
#include <linux/seq_file.h>
#include <linux/rcupdate.h>
#include <linux/kernel_stat.h>
#include <linux/err.h>

#include "sched.h"

/*
 * CPU accounting code for task groups.
 *
 * Based on the work by Paul Menage (menage@google.com) and Balbir Singh
 * (balbir@in.ibm.com).
 */

/* Time spent by the tasks of the cpu accounting group executing in ... */
enum cpuacct_stat_index {
	CPUACCT_STAT_USER,	/* ... user mode */
	CPUACCT_STAT_SYSTEM,	/* ... kernel mode */

	CPUACCT_STAT_NSTATS,
};

/* track cpu usage of a group of tasks and its child groups */
struct cpuacct {
	struct cgroup_subsys_state css;
	/* cpuusage holds pointer to a u64-type object on every cpu */
	u64 __percpu *cpuusage;
	struct kernel_cpustat __percpu *cpustat;
};

static inline struct cpuacct *css_ca(struct cgroup_subsys_state *css)
{
	return css ? container_of(css, struct cpuacct, css) : NULL;
}

/* return cpu accounting group to which this task belongs */
static inline struct cpuacct *task_ca(struct task_struct *tsk)
{
	return css_ca(task_css(tsk, cpuacct_cgrp_id));
}

static inline struct cpuacct *parent_ca(struct cpuacct *ca)
{
	return css_ca(ca->css.parent);
}

static DEFINE_PER_CPU(u64, root_cpuacct_cpuusage);
static struct cpuacct root_cpuacct = {
	.cpustat	= &kernel_cpustat,
	.cpuusage	= &root_cpuacct_cpuusage,
};

/* create a new cpu accounting group */
static struct cgroup_subsys_state *
cpuacct_css_alloc(struct cgroup_subsys_state *parent_css)
{
	struct cpuacct *ca;

	if (!parent_css)
		return &root_cpuacct.css;

	ca = kzalloc(sizeof(*ca), GFP_KERNEL);
	if (!ca)
		goto out;

	ca->cpuusage = alloc_percpu(u64);
	if (!ca->cpuusage)
		goto out_free_ca;

	ca->cpustat = alloc_percpu(struct kernel_cpustat);
	if (!ca->cpustat)
		goto out_free_cpuusage;

	return &ca->css;

out_free_cpuusage:
	free_percpu(ca->cpuusage);
out_free_ca:
	kfree(ca);
out:
	return ERR_PTR(-ENOMEM);
}

/* destroy an existing cpu accounting group */
static void cpuacct_css_free(struct cgroup_subsys_state *css)
{
	struct cpuacct *ca = css_ca(css);

	free_percpu(ca->cpustat);
	free_percpu(ca->cpuusage);
	kfree(ca);
}

static u64 cpuacct_cpuusage_read(struct cpuacct *ca, int cpu)
{
	u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
	u64 data;

#ifndef CONFIG_64BIT
	/*
	 * Take rq->lock to make 64-bit read safe on 32-bit platforms.
	 */
	raw_spin_lock_irq(&cpu_rq(cpu)->lock);
	data = *cpuusage;
	raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
#else
	data = *cpuusage;
#endif

	return data;
}

static void cpuacct_cpuusage_write(struct cpuacct *ca, int cpu, u64 val)
{
	u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);

#ifndef CONFIG_64BIT
	/*
	 * Take rq->lock to make 64-bit write safe on 32-bit platforms.
	 */
	raw_spin_lock_irq(&cpu_rq(cpu)->lock);
	*cpuusage = val;
	raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
#else
	*cpuusage = val;
#endif
}

/* return total cpu usage (in nanoseconds) of a group */
static u64 cpuusage_read(struct cgroup_subsys_state *css, struct cftype *cft)
{
	struct cpuacct *ca = css_ca(css);
	u64 totalcpuusage = 0;
	int i;

	for_each_present_cpu(i)
		totalcpuusage += cpuacct_cpuusage_read(ca, i);

	return totalcpuusage;
}

static int cpuusage_write(struct cgroup_subsys_state *css, struct cftype *cft,
			  u64 reset)
{
	struct cpuacct *ca = css_ca(css);
	int err = 0;
	int i;

	if (reset) {
		err = -EINVAL;
		goto out;
	}

	for_each_present_cpu(i)
		cpuacct_cpuusage_write(ca, i, 0);

out:
	return err;
}

static int cpuacct_percpu_seq_show(struct seq_file *m, void *V)
{
	struct cpuacct *ca = css_ca(seq_css(m));
	u64 percpu;
	int i;

	for_each_present_cpu(i) {
		percpu = cpuacct_cpuusage_read(ca, i);
		seq_printf(m, "%llu ", (unsigned long long) percpu);
	}
	seq_printf(m, "\n");
	return 0;
}

static const char * const cpuacct_stat_desc[] = {
	[CPUACCT_STAT_USER] = "user",
	[CPUACCT_STAT_SYSTEM] = "system",
};

static int cpuacct_stats_show(struct seq_file *sf, void *v)
{
	struct cpuacct *ca = css_ca(seq_css(sf));
	int cpu;
	s64 val = 0;

	for_each_online_cpu(cpu) {
		struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu);
		val += kcpustat->cpustat[CPUTIME_USER];
		val += kcpustat->cpustat[CPUTIME_NICE];
	}
	val = cputime64_to_clock_t(val);
	seq_printf(sf, "%s %lld\n", cpuacct_stat_desc[CPUACCT_STAT_USER], val);

	val = 0;
	for_each_online_cpu(cpu) {
		struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu);
		val += kcpustat->cpustat[CPUTIME_SYSTEM];
		val += kcpustat->cpustat[CPUTIME_IRQ];
		val += kcpustat->cpustat[CPUTIME_SOFTIRQ];
	}

	val = cputime64_to_clock_t(val);
	seq_printf(sf, "%s %lld\n", cpuacct_stat_desc[CPUACCT_STAT_SYSTEM], val);

	return 0;
}

static struct cftype files[] = {
	{
		.name = "usage",
		.read_u64 = cpuusage_read,
		.write_u64 = cpuusage_write,
	},
	{
		.name = "usage_percpu",
		.seq_show = cpuacct_percpu_seq_show,
	},
	{
		.name = "stat",
		.seq_show = cpuacct_stats_show,
	},
	{ }	/* terminate */
};

/*
 * charge this task's execution time to its accounting group.
 *
 * called with rq->lock held.
 */
void cpuacct_charge(struct task_struct *tsk, u64 cputime)
{
	struct cpuacct *ca;
	int cpu;

	cpu = task_cpu(tsk);

	rcu_read_lock();

	ca = task_ca(tsk);

	while (true) {
		u64 *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
		*cpuusage += cputime;

		ca = parent_ca(ca);
		if (!ca)
			break;
	}

	rcu_read_unlock();
}

/*
 * Add user/system time to cpuacct.
 *
 * Note: it's the caller that updates the account of the root cgroup.
 */
void cpuacct_account_field(struct task_struct *p, int index, u64 val)
{
	struct kernel_cpustat *kcpustat;
	struct cpuacct *ca;

	rcu_read_lock();
	ca = task_ca(p);
	while (ca != &root_cpuacct) {
		kcpustat = this_cpu_ptr(ca->cpustat);
		kcpustat->cpustat[index] += val;
		ca = parent_ca(ca);
	}
	rcu_read_unlock();
}

struct cgroup_subsys cpuacct_cgrp_subsys = {
	.css_alloc	= cpuacct_css_alloc,
	.css_free	= cpuacct_css_free,
	.legacy_cftypes	= files,
	.early_init	= 1,
};
OpenPOWER on IntegriCloud