Loading...
Note: File does not exist in v3.5.6.
1// SPDX-License-Identifier: GPL-2.0-only
2#include "cgroup-internal.h"
3
4#include <linux/sched/cputime.h>
5
6static DEFINE_SPINLOCK(cgroup_rstat_lock);
7static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock);
8
9static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu);
10
11static struct cgroup_rstat_cpu *cgroup_rstat_cpu(struct cgroup *cgrp, int cpu)
12{
13 return per_cpu_ptr(cgrp->rstat_cpu, cpu);
14}
15
16/**
17 * cgroup_rstat_updated - keep track of updated rstat_cpu
18 * @cgrp: target cgroup
19 * @cpu: cpu on which rstat_cpu was updated
20 *
21 * @cgrp's rstat_cpu on @cpu was updated. Put it on the parent's matching
22 * rstat_cpu->updated_children list. See the comment on top of
23 * cgroup_rstat_cpu definition for details.
24 */
25void cgroup_rstat_updated(struct cgroup *cgrp, int cpu)
26{
27 raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu);
28 struct cgroup *parent;
29 unsigned long flags;
30
31 /* nothing to do for root */
32 if (!cgroup_parent(cgrp))
33 return;
34
35 /*
36 * Paired with the one in cgroup_rstat_cpu_pop_upated(). Either we
37 * see NULL updated_next or they see our updated stat.
38 */
39 smp_mb();
40
41 /*
42 * Because @parent's updated_children is terminated with @parent
43 * instead of NULL, we can tell whether @cgrp is on the list by
44 * testing the next pointer for NULL.
45 */
46 if (cgroup_rstat_cpu(cgrp, cpu)->updated_next)
47 return;
48
49 raw_spin_lock_irqsave(cpu_lock, flags);
50
51 /* put @cgrp and all ancestors on the corresponding updated lists */
52 for (parent = cgroup_parent(cgrp); parent;
53 cgrp = parent, parent = cgroup_parent(cgrp)) {
54 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
55 struct cgroup_rstat_cpu *prstatc = cgroup_rstat_cpu(parent, cpu);
56
57 /*
58 * Both additions and removals are bottom-up. If a cgroup
59 * is already in the tree, all ancestors are.
60 */
61 if (rstatc->updated_next)
62 break;
63
64 rstatc->updated_next = prstatc->updated_children;
65 prstatc->updated_children = cgrp;
66 }
67
68 raw_spin_unlock_irqrestore(cpu_lock, flags);
69}
70EXPORT_SYMBOL_GPL(cgroup_rstat_updated);
71
72/**
73 * cgroup_rstat_cpu_pop_updated - iterate and dismantle rstat_cpu updated tree
74 * @pos: current position
75 * @root: root of the tree to traversal
76 * @cpu: target cpu
77 *
78 * Walks the udpated rstat_cpu tree on @cpu from @root. %NULL @pos starts
79 * the traversal and %NULL return indicates the end. During traversal,
80 * each returned cgroup is unlinked from the tree. Must be called with the
81 * matching cgroup_rstat_cpu_lock held.
82 *
83 * The only ordering guarantee is that, for a parent and a child pair
84 * covered by a given traversal, if a child is visited, its parent is
85 * guaranteed to be visited afterwards.
86 */
87static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos,
88 struct cgroup *root, int cpu)
89{
90 struct cgroup_rstat_cpu *rstatc;
91
92 if (pos == root)
93 return NULL;
94
95 /*
96 * We're gonna walk down to the first leaf and visit/remove it. We
97 * can pick whatever unvisited node as the starting point.
98 */
99 if (!pos)
100 pos = root;
101 else
102 pos = cgroup_parent(pos);
103
104 /* walk down to the first leaf */
105 while (true) {
106 rstatc = cgroup_rstat_cpu(pos, cpu);
107 if (rstatc->updated_children == pos)
108 break;
109 pos = rstatc->updated_children;
110 }
111
112 /*
113 * Unlink @pos from the tree. As the updated_children list is
114 * singly linked, we have to walk it to find the removal point.
115 * However, due to the way we traverse, @pos will be the first
116 * child in most cases. The only exception is @root.
117 */
118 if (rstatc->updated_next) {
119 struct cgroup *parent = cgroup_parent(pos);
120 struct cgroup_rstat_cpu *prstatc = cgroup_rstat_cpu(parent, cpu);
121 struct cgroup_rstat_cpu *nrstatc;
122 struct cgroup **nextp;
123
124 nextp = &prstatc->updated_children;
125 while (true) {
126 nrstatc = cgroup_rstat_cpu(*nextp, cpu);
127 if (*nextp == pos)
128 break;
129
130 WARN_ON_ONCE(*nextp == parent);
131 nextp = &nrstatc->updated_next;
132 }
133
134 *nextp = rstatc->updated_next;
135 rstatc->updated_next = NULL;
136
137 /*
138 * Paired with the one in cgroup_rstat_cpu_updated().
139 * Either they see NULL updated_next or we see their
140 * updated stat.
141 */
142 smp_mb();
143
144 return pos;
145 }
146
147 /* only happens for @root */
148 return NULL;
149}
150
151/* see cgroup_rstat_flush() */
152static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
153 __releases(&cgroup_rstat_lock) __acquires(&cgroup_rstat_lock)
154{
155 int cpu;
156
157 lockdep_assert_held(&cgroup_rstat_lock);
158
159 for_each_possible_cpu(cpu) {
160 raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock,
161 cpu);
162 struct cgroup *pos = NULL;
163
164 raw_spin_lock(cpu_lock);
165 while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu))) {
166 struct cgroup_subsys_state *css;
167
168 cgroup_base_stat_flush(pos, cpu);
169
170 rcu_read_lock();
171 list_for_each_entry_rcu(css, &pos->rstat_css_list,
172 rstat_css_node)
173 css->ss->css_rstat_flush(css, cpu);
174 rcu_read_unlock();
175 }
176 raw_spin_unlock(cpu_lock);
177
178 /* if @may_sleep, play nice and yield if necessary */
179 if (may_sleep && (need_resched() ||
180 spin_needbreak(&cgroup_rstat_lock))) {
181 spin_unlock_irq(&cgroup_rstat_lock);
182 if (!cond_resched())
183 cpu_relax();
184 spin_lock_irq(&cgroup_rstat_lock);
185 }
186 }
187}
188
189/**
190 * cgroup_rstat_flush - flush stats in @cgrp's subtree
191 * @cgrp: target cgroup
192 *
193 * Collect all per-cpu stats in @cgrp's subtree into the global counters
194 * and propagate them upwards. After this function returns, all cgroups in
195 * the subtree have up-to-date ->stat.
196 *
197 * This also gets all cgroups in the subtree including @cgrp off the
198 * ->updated_children lists.
199 *
200 * This function may block.
201 */
202void cgroup_rstat_flush(struct cgroup *cgrp)
203{
204 might_sleep();
205
206 spin_lock_irq(&cgroup_rstat_lock);
207 cgroup_rstat_flush_locked(cgrp, true);
208 spin_unlock_irq(&cgroup_rstat_lock);
209}
210
211/**
212 * cgroup_rstat_flush_irqsafe - irqsafe version of cgroup_rstat_flush()
213 * @cgrp: target cgroup
214 *
215 * This function can be called from any context.
216 */
217void cgroup_rstat_flush_irqsafe(struct cgroup *cgrp)
218{
219 unsigned long flags;
220
221 spin_lock_irqsave(&cgroup_rstat_lock, flags);
222 cgroup_rstat_flush_locked(cgrp, false);
223 spin_unlock_irqrestore(&cgroup_rstat_lock, flags);
224}
225
226/**
227 * cgroup_rstat_flush_begin - flush stats in @cgrp's subtree and hold
228 * @cgrp: target cgroup
229 *
230 * Flush stats in @cgrp's subtree and prevent further flushes. Must be
231 * paired with cgroup_rstat_flush_release().
232 *
233 * This function may block.
234 */
235void cgroup_rstat_flush_hold(struct cgroup *cgrp)
236 __acquires(&cgroup_rstat_lock)
237{
238 might_sleep();
239 spin_lock_irq(&cgroup_rstat_lock);
240 cgroup_rstat_flush_locked(cgrp, true);
241}
242
243/**
244 * cgroup_rstat_flush_release - release cgroup_rstat_flush_hold()
245 */
246void cgroup_rstat_flush_release(void)
247 __releases(&cgroup_rstat_lock)
248{
249 spin_unlock_irq(&cgroup_rstat_lock);
250}
251
252int cgroup_rstat_init(struct cgroup *cgrp)
253{
254 int cpu;
255
256 /* the root cgrp has rstat_cpu preallocated */
257 if (!cgrp->rstat_cpu) {
258 cgrp->rstat_cpu = alloc_percpu(struct cgroup_rstat_cpu);
259 if (!cgrp->rstat_cpu)
260 return -ENOMEM;
261 }
262
263 /* ->updated_children list is self terminated */
264 for_each_possible_cpu(cpu) {
265 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
266
267 rstatc->updated_children = cgrp;
268 u64_stats_init(&rstatc->bsync);
269 }
270
271 return 0;
272}
273
274void cgroup_rstat_exit(struct cgroup *cgrp)
275{
276 int cpu;
277
278 cgroup_rstat_flush(cgrp);
279
280 /* sanity check */
281 for_each_possible_cpu(cpu) {
282 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
283
284 if (WARN_ON_ONCE(rstatc->updated_children != cgrp) ||
285 WARN_ON_ONCE(rstatc->updated_next))
286 return;
287 }
288
289 free_percpu(cgrp->rstat_cpu);
290 cgrp->rstat_cpu = NULL;
291}
292
293void __init cgroup_rstat_boot(void)
294{
295 int cpu;
296
297 for_each_possible_cpu(cpu)
298 raw_spin_lock_init(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu));
299
300 BUG_ON(cgroup_rstat_init(&cgrp_dfl_root.cgrp));
301}
302
303/*
304 * Functions for cgroup basic resource statistics implemented on top of
305 * rstat.
306 */
307static void cgroup_base_stat_accumulate(struct cgroup_base_stat *dst_bstat,
308 struct cgroup_base_stat *src_bstat)
309{
310 dst_bstat->cputime.utime += src_bstat->cputime.utime;
311 dst_bstat->cputime.stime += src_bstat->cputime.stime;
312 dst_bstat->cputime.sum_exec_runtime += src_bstat->cputime.sum_exec_runtime;
313}
314
315static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu)
316{
317 struct cgroup *parent = cgroup_parent(cgrp);
318 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
319 struct task_cputime *last_cputime = &rstatc->last_bstat.cputime;
320 struct task_cputime cputime;
321 struct cgroup_base_stat delta;
322 unsigned seq;
323
324 /* fetch the current per-cpu values */
325 do {
326 seq = __u64_stats_fetch_begin(&rstatc->bsync);
327 cputime = rstatc->bstat.cputime;
328 } while (__u64_stats_fetch_retry(&rstatc->bsync, seq));
329
330 /* calculate the delta to propgate */
331 delta.cputime.utime = cputime.utime - last_cputime->utime;
332 delta.cputime.stime = cputime.stime - last_cputime->stime;
333 delta.cputime.sum_exec_runtime = cputime.sum_exec_runtime -
334 last_cputime->sum_exec_runtime;
335 *last_cputime = cputime;
336
337 /* transfer the pending stat into delta */
338 cgroup_base_stat_accumulate(&delta, &cgrp->pending_bstat);
339 memset(&cgrp->pending_bstat, 0, sizeof(cgrp->pending_bstat));
340
341 /* propagate delta into the global stat and the parent's pending */
342 cgroup_base_stat_accumulate(&cgrp->bstat, &delta);
343 if (parent)
344 cgroup_base_stat_accumulate(&parent->pending_bstat, &delta);
345}
346
347static struct cgroup_rstat_cpu *
348cgroup_base_stat_cputime_account_begin(struct cgroup *cgrp)
349{
350 struct cgroup_rstat_cpu *rstatc;
351
352 rstatc = get_cpu_ptr(cgrp->rstat_cpu);
353 u64_stats_update_begin(&rstatc->bsync);
354 return rstatc;
355}
356
357static void cgroup_base_stat_cputime_account_end(struct cgroup *cgrp,
358 struct cgroup_rstat_cpu *rstatc)
359{
360 u64_stats_update_end(&rstatc->bsync);
361 cgroup_rstat_updated(cgrp, smp_processor_id());
362 put_cpu_ptr(rstatc);
363}
364
365void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec)
366{
367 struct cgroup_rstat_cpu *rstatc;
368
369 rstatc = cgroup_base_stat_cputime_account_begin(cgrp);
370 rstatc->bstat.cputime.sum_exec_runtime += delta_exec;
371 cgroup_base_stat_cputime_account_end(cgrp, rstatc);
372}
373
374void __cgroup_account_cputime_field(struct cgroup *cgrp,
375 enum cpu_usage_stat index, u64 delta_exec)
376{
377 struct cgroup_rstat_cpu *rstatc;
378
379 rstatc = cgroup_base_stat_cputime_account_begin(cgrp);
380
381 switch (index) {
382 case CPUTIME_USER:
383 case CPUTIME_NICE:
384 rstatc->bstat.cputime.utime += delta_exec;
385 break;
386 case CPUTIME_SYSTEM:
387 case CPUTIME_IRQ:
388 case CPUTIME_SOFTIRQ:
389 rstatc->bstat.cputime.stime += delta_exec;
390 break;
391 default:
392 break;
393 }
394
395 cgroup_base_stat_cputime_account_end(cgrp, rstatc);
396}
397
398void cgroup_base_stat_cputime_show(struct seq_file *seq)
399{
400 struct cgroup *cgrp = seq_css(seq)->cgroup;
401 u64 usage, utime, stime;
402
403 if (!cgroup_parent(cgrp))
404 return;
405
406 cgroup_rstat_flush_hold(cgrp);
407 usage = cgrp->bstat.cputime.sum_exec_runtime;
408 cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime, &utime, &stime);
409 cgroup_rstat_flush_release();
410
411 do_div(usage, NSEC_PER_USEC);
412 do_div(utime, NSEC_PER_USEC);
413 do_div(stime, NSEC_PER_USEC);
414
415 seq_printf(seq, "usage_usec %llu\n"
416 "user_usec %llu\n"
417 "system_usec %llu\n",
418 usage, utime, stime);
419}