summaryrefslogtreecommitdiffstats
path: root/kernel/cgroup/stat.c
blob: 133b465691d6fe82462c33215639b6b7f97f04b7 (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
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
#include "cgroup-internal.h"

#include <linux/sched/cputime.h>

static DEFINE_MUTEX(cgroup_stat_mutex);
static DEFINE_PER_CPU(raw_spinlock_t, cgroup_cpu_stat_lock);

static struct cgroup_cpu_stat *cgroup_cpu_stat(struct cgroup *cgrp, int cpu)
{
	return per_cpu_ptr(cgrp->cpu_stat, cpu);
}

/**
 * cgroup_cpu_stat_updated - keep track of updated cpu_stat
 * @cgrp: target cgroup
 * @cpu: cpu on which cpu_stat was updated
 *
 * @cgrp's cpu_stat on @cpu was updated.  Put it on the parent's matching
 * cpu_stat->updated_children list.  See the comment on top of
 * cgroup_cpu_stat definition for details.
 */
static void cgroup_cpu_stat_updated(struct cgroup *cgrp, int cpu)
{
	raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_cpu_stat_lock, cpu);
	struct cgroup *parent;
	unsigned long flags;

	/*
	 * Speculative already-on-list test.  This may race leading to
	 * temporary inaccuracies, which is fine.
	 *
	 * Because @parent's updated_children is terminated with @parent
	 * instead of NULL, we can tell whether @cgrp is on the list by
	 * testing the next pointer for NULL.
	 */
	if (cgroup_cpu_stat(cgrp, cpu)->updated_next)
		return;

	raw_spin_lock_irqsave(cpu_lock, flags);

	/* put @cgrp and all ancestors on the corresponding updated lists */
	for (parent = cgroup_parent(cgrp); parent;
	     cgrp = parent, parent = cgroup_parent(cgrp)) {
		struct cgroup_cpu_stat *cstat = cgroup_cpu_stat(cgrp, cpu);
		struct cgroup_cpu_stat *pcstat = cgroup_cpu_stat(parent, cpu);

		/*
		 * Both additions and removals are bottom-up.  If a cgroup
		 * is already in the tree, all ancestors are.
		 */
		if (cstat->updated_next)
			break;

		cstat->updated_next = pcstat->updated_children;
		pcstat->updated_children = cgrp;
	}

	raw_spin_unlock_irqrestore(cpu_lock, flags);
}

/**
 * cgroup_cpu_stat_pop_updated - iterate and dismantle cpu_stat updated tree
 * @pos: current position
 * @root: root of the tree to traversal
 * @cpu: target cpu
 *
 * Walks the udpated cpu_stat tree on @cpu from @root.  %NULL @pos starts
 * the traversal and %NULL return indicates the end.  During traversal,
 * each returned cgroup is unlinked from the tree.  Must be called with the
 * matching cgroup_cpu_stat_lock held.
 *
 * The only ordering guarantee is that, for a parent and a child pair
 * covered by a given traversal, if a child is visited, its parent is
 * guaranteed to be visited afterwards.
 */
static struct cgroup *cgroup_cpu_stat_pop_updated(struct cgroup *pos,
						  struct cgroup *root, int cpu)
{
	struct cgroup_cpu_stat *cstat;
	struct cgroup *parent;

	if (pos == root)
		return NULL;

	/*
	 * We're gonna walk down to the first leaf and visit/remove it.  We
	 * can pick whatever unvisited node as the starting point.
	 */
	if (!pos)
		pos = root;
	else
		pos = cgroup_parent(pos);

	/* walk down to the first leaf */
	while (true) {
		cstat = cgroup_cpu_stat(pos, cpu);
		if (cstat->updated_children == pos)
			break;
		pos = cstat->updated_children;
	}

	/*
	 * Unlink @pos from the tree.  As the updated_children list is
	 * singly linked, we have to walk it to find the removal point.
	 * However, due to the way we traverse, @pos will be the first
	 * child in most cases. The only exception is @root.
	 */
	parent = cgroup_parent(pos);
	if (parent && cstat->updated_next) {
		struct cgroup_cpu_stat *pcstat = cgroup_cpu_stat(parent, cpu);
		struct cgroup_cpu_stat *ncstat;
		struct cgroup **nextp;

		nextp = &pcstat->updated_children;
		while (true) {
			ncstat = cgroup_cpu_stat(*nextp, cpu);
			if (*nextp == pos)
				break;

			WARN_ON_ONCE(*nextp == parent);
			nextp = &ncstat->updated_next;
		}

		*nextp = cstat->updated_next;
		cstat->updated_next = NULL;
	}

	return pos;
}

static void cgroup_stat_accumulate(struct cgroup_stat *dst_stat,
				   struct cgroup_stat *src_stat)
{
	dst_stat->cputime.utime += src_stat->cputime.utime;
	dst_stat->cputime.stime += src_stat->cputime.stime;
	dst_stat->cputime.sum_exec_runtime += src_stat->cputime.sum_exec_runtime;
}

static void cgroup_cpu_stat_flush_one(struct cgroup *cgrp, int cpu)
{
	struct cgroup *parent = cgroup_parent(cgrp);
	struct cgroup_cpu_stat *cstat = cgroup_cpu_stat(cgrp, cpu);
	struct task_cputime *last_cputime = &cstat->last_cputime;
	struct task_cputime cputime;
	struct cgroup_stat delta;
	unsigned seq;

	lockdep_assert_held(&cgroup_stat_mutex);

	/* fetch the current per-cpu values */
	do {
		seq = __u64_stats_fetch_begin(&cstat->sync);
		cputime = cstat->cputime;
	} while (__u64_stats_fetch_retry(&cstat->sync, seq));

	/* accumulate the deltas to propgate */
	delta.cputime.utime = cputime.utime - last_cputime->utime;
	delta.cputime.stime = cputime.stime - last_cputime->stime;
	delta.cputime.sum_exec_runtime = cputime.sum_exec_runtime -
					 last_cputime->sum_exec_runtime;
	*last_cputime = cputime;

	/* transfer the pending stat into delta */
	cgroup_stat_accumulate(&delta, &cgrp->pending_stat);
	memset(&cgrp->pending_stat, 0, sizeof(cgrp->pending_stat));

	/* propagate delta into the global stat and the parent's pending */
	cgroup_stat_accumulate(&cgrp->stat, &delta);
	if (parent)
		cgroup_stat_accumulate(&parent->pending_stat, &delta);
}

/* see cgroup_stat_flush() */
static void cgroup_stat_flush_locked(struct cgroup *cgrp)
{
	int cpu;

	lockdep_assert_held(&cgroup_stat_mutex);

	for_each_possible_cpu(cpu) {
		raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_cpu_stat_lock, cpu);
		struct cgroup *pos = NULL;

		raw_spin_lock_irq(cpu_lock);
		while ((pos = cgroup_cpu_stat_pop_updated(pos, cgrp, cpu)))
			cgroup_cpu_stat_flush_one(pos, cpu);
		raw_spin_unlock_irq(cpu_lock);
	}
}

/**
 * cgroup_stat_flush - flush stats in @cgrp's subtree
 * @cgrp: target cgroup
 *
 * Collect all per-cpu stats in @cgrp's subtree into the global counters
 * and propagate them upwards.  After this function returns, all cgroups in
 * the subtree have up-to-date ->stat.
 *
 * This also gets all cgroups in the subtree including @cgrp off the
 * ->updated_children lists.
 */
void cgroup_stat_flush(struct cgroup *cgrp)
{
	mutex_lock(&cgroup_stat_mutex);
	cgroup_stat_flush_locked(cgrp);
	mutex_unlock(&cgroup_stat_mutex);
}

static struct cgroup_cpu_stat *cgroup_cpu_stat_account_begin(struct cgroup *cgrp)
{
	struct cgroup_cpu_stat *cstat;

	cstat = get_cpu_ptr(cgrp->cpu_stat);
	u64_stats_update_begin(&cstat->sync);
	return cstat;
}

static void cgroup_cpu_stat_account_end(struct cgroup *cgrp,
					struct cgroup_cpu_stat *cstat)
{
	u64_stats_update_end(&cstat->sync);
	cgroup_cpu_stat_updated(cgrp, smp_processor_id());
	put_cpu_ptr(cstat);
}

void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec)
{
	struct cgroup_cpu_stat *cstat;

	cstat = cgroup_cpu_stat_account_begin(cgrp);
	cstat->cputime.sum_exec_runtime += delta_exec;
	cgroup_cpu_stat_account_end(cgrp, cstat);
}

void __cgroup_account_cputime_field(struct cgroup *cgrp,
				    enum cpu_usage_stat index, u64 delta_exec)
{
	struct cgroup_cpu_stat *cstat;

	cstat = cgroup_cpu_stat_account_begin(cgrp);

	switch (index) {
	case CPUTIME_USER:
	case CPUTIME_NICE:
		cstat->cputime.utime += delta_exec;
		break;
	case CPUTIME_SYSTEM:
	case CPUTIME_IRQ:
	case CPUTIME_SOFTIRQ:
		cstat->cputime.stime += delta_exec;
		break;
	default:
		break;
	}

	cgroup_cpu_stat_account_end(cgrp, cstat);
}

void cgroup_stat_show_cputime(struct seq_file *seq)
{
	struct cgroup *cgrp = seq_css(seq)->cgroup;
	u64 usage, utime, stime;

	if (!cgroup_parent(cgrp))
		return;

	mutex_lock(&cgroup_stat_mutex);

	cgroup_stat_flush_locked(cgrp);

	usage = cgrp->stat.cputime.sum_exec_runtime;
	cputime_adjust(&cgrp->stat.cputime, &cgrp->stat.prev_cputime,
		       &utime, &stime);

	mutex_unlock(&cgroup_stat_mutex);

	do_div(usage, NSEC_PER_USEC);
	do_div(utime, NSEC_PER_USEC);
	do_div(stime, NSEC_PER_USEC);

	seq_printf(seq, "usage_usec %llu\n"
		   "user_usec %llu\n"
		   "system_usec %llu\n",
		   usage, utime, stime);
}

int cgroup_stat_init(struct cgroup *cgrp)
{
	int cpu;

	/* the root cgrp has cpu_stat preallocated */
	if (!cgrp->cpu_stat) {
		cgrp->cpu_stat = alloc_percpu(struct cgroup_cpu_stat);
		if (!cgrp->cpu_stat)
			return -ENOMEM;
	}

	/* ->updated_children list is self terminated */
	for_each_possible_cpu(cpu)
		cgroup_cpu_stat(cgrp, cpu)->updated_children = cgrp;

	prev_cputime_init(&cgrp->stat.prev_cputime);

	return 0;
}

void cgroup_stat_exit(struct cgroup *cgrp)
{
	int cpu;

	cgroup_stat_flush(cgrp);

	/* sanity check */
	for_each_possible_cpu(cpu) {
		struct cgroup_cpu_stat *cstat = cgroup_cpu_stat(cgrp, cpu);

		if (WARN_ON_ONCE(cstat->updated_children != cgrp) ||
		    WARN_ON_ONCE(cstat->updated_next))
			return;
	}

	free_percpu(cgrp->cpu_stat);
	cgrp->cpu_stat = NULL;
}

void __init cgroup_stat_boot(void)
{
	int cpu;

	for_each_possible_cpu(cpu)
		raw_spin_lock_init(per_cpu_ptr(&cgroup_cpu_stat_lock, cpu));

	BUG_ON(cgroup_stat_init(&cgrp_dfl_root.cgrp));
}
OpenPOWER on IntegriCloud