1 // SPDX-License-Identifier: GPL-2.0-only
2 #include "cgroup-internal.h"
4 #include <linux/sched/cputime.h>
6 static DEFINE_SPINLOCK(cgroup_rstat_lock);
7 static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock);
9 static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu);
11 static struct cgroup_rstat_cpu *cgroup_rstat_cpu(struct cgroup *cgrp, int cpu)
13 return per_cpu_ptr(cgrp->rstat_cpu, cpu);
17 * cgroup_rstat_updated - keep track of updated rstat_cpu
18 * @cgrp: target cgroup
19 * @cpu: cpu on which rstat_cpu was updated
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.
25 void cgroup_rstat_updated(struct cgroup *cgrp, int cpu)
27 raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu);
31 * Speculative already-on-list test. This may race leading to
32 * temporary inaccuracies, which is fine.
34 * Because @parent's updated_children is terminated with @parent
35 * instead of NULL, we can tell whether @cgrp is on the list by
36 * testing the next pointer for NULL.
38 if (cgroup_rstat_cpu(cgrp, cpu)->updated_next)
41 raw_spin_lock_irqsave(cpu_lock, flags);
43 /* put @cgrp and all ancestors on the corresponding updated lists */
45 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
46 struct cgroup *parent = cgroup_parent(cgrp);
47 struct cgroup_rstat_cpu *prstatc;
50 * Both additions and removals are bottom-up. If a cgroup
51 * is already in the tree, all ancestors are.
53 if (rstatc->updated_next)
56 /* Root has no parent to link it to, but mark it busy */
58 rstatc->updated_next = cgrp;
62 prstatc = cgroup_rstat_cpu(parent, cpu);
63 rstatc->updated_next = prstatc->updated_children;
64 prstatc->updated_children = cgrp;
69 raw_spin_unlock_irqrestore(cpu_lock, flags);
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
78 * Walks the updated 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.
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.
87 static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos,
88 struct cgroup *root, int cpu)
90 struct cgroup_rstat_cpu *rstatc;
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.
102 pos = cgroup_parent(pos);
104 /* walk down to the first leaf */
106 rstatc = cgroup_rstat_cpu(pos, cpu);
107 if (rstatc->updated_children == pos)
109 pos = rstatc->updated_children;
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.
118 if (rstatc->updated_next) {
119 struct cgroup *parent = cgroup_parent(pos);
122 struct cgroup_rstat_cpu *prstatc;
123 struct cgroup **nextp;
125 prstatc = cgroup_rstat_cpu(parent, cpu);
126 nextp = &prstatc->updated_children;
128 struct cgroup_rstat_cpu *nrstatc;
130 nrstatc = cgroup_rstat_cpu(*nextp, cpu);
133 WARN_ON_ONCE(*nextp == parent);
134 nextp = &nrstatc->updated_next;
136 *nextp = rstatc->updated_next;
139 rstatc->updated_next = NULL;
143 /* only happens for @root */
147 /* see cgroup_rstat_flush() */
148 static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
149 __releases(&cgroup_rstat_lock) __acquires(&cgroup_rstat_lock)
153 lockdep_assert_held(&cgroup_rstat_lock);
155 for_each_possible_cpu(cpu) {
156 raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock,
158 struct cgroup *pos = NULL;
160 raw_spin_lock(cpu_lock);
161 while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu))) {
162 struct cgroup_subsys_state *css;
164 cgroup_base_stat_flush(pos, cpu);
167 list_for_each_entry_rcu(css, &pos->rstat_css_list,
169 css->ss->css_rstat_flush(css, cpu);
172 raw_spin_unlock(cpu_lock);
174 /* if @may_sleep, play nice and yield if necessary */
175 if (may_sleep && (need_resched() ||
176 spin_needbreak(&cgroup_rstat_lock))) {
177 spin_unlock_irq(&cgroup_rstat_lock);
180 spin_lock_irq(&cgroup_rstat_lock);
186 * cgroup_rstat_flush - flush stats in @cgrp's subtree
187 * @cgrp: target cgroup
189 * Collect all per-cpu stats in @cgrp's subtree into the global counters
190 * and propagate them upwards. After this function returns, all cgroups in
191 * the subtree have up-to-date ->stat.
193 * This also gets all cgroups in the subtree including @cgrp off the
194 * ->updated_children lists.
196 * This function may block.
198 void cgroup_rstat_flush(struct cgroup *cgrp)
202 spin_lock_irq(&cgroup_rstat_lock);
203 cgroup_rstat_flush_locked(cgrp, true);
204 spin_unlock_irq(&cgroup_rstat_lock);
208 * cgroup_rstat_flush_irqsafe - irqsafe version of cgroup_rstat_flush()
209 * @cgrp: target cgroup
211 * This function can be called from any context.
213 void cgroup_rstat_flush_irqsafe(struct cgroup *cgrp)
217 spin_lock_irqsave(&cgroup_rstat_lock, flags);
218 cgroup_rstat_flush_locked(cgrp, false);
219 spin_unlock_irqrestore(&cgroup_rstat_lock, flags);
223 * cgroup_rstat_flush_hold - flush stats in @cgrp's subtree and hold
224 * @cgrp: target cgroup
226 * Flush stats in @cgrp's subtree and prevent further flushes. Must be
227 * paired with cgroup_rstat_flush_release().
229 * This function may block.
231 void cgroup_rstat_flush_hold(struct cgroup *cgrp)
232 __acquires(&cgroup_rstat_lock)
235 spin_lock_irq(&cgroup_rstat_lock);
236 cgroup_rstat_flush_locked(cgrp, true);
240 * cgroup_rstat_flush_release - release cgroup_rstat_flush_hold()
242 void cgroup_rstat_flush_release(void)
243 __releases(&cgroup_rstat_lock)
245 spin_unlock_irq(&cgroup_rstat_lock);
248 int cgroup_rstat_init(struct cgroup *cgrp)
252 /* the root cgrp has rstat_cpu preallocated */
253 if (!cgrp->rstat_cpu) {
254 cgrp->rstat_cpu = alloc_percpu(struct cgroup_rstat_cpu);
255 if (!cgrp->rstat_cpu)
259 /* ->updated_children list is self terminated */
260 for_each_possible_cpu(cpu) {
261 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
263 rstatc->updated_children = cgrp;
264 u64_stats_init(&rstatc->bsync);
270 void cgroup_rstat_exit(struct cgroup *cgrp)
274 cgroup_rstat_flush(cgrp);
277 for_each_possible_cpu(cpu) {
278 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
280 if (WARN_ON_ONCE(rstatc->updated_children != cgrp) ||
281 WARN_ON_ONCE(rstatc->updated_next))
285 free_percpu(cgrp->rstat_cpu);
286 cgrp->rstat_cpu = NULL;
289 void __init cgroup_rstat_boot(void)
293 for_each_possible_cpu(cpu)
294 raw_spin_lock_init(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu));
298 * Functions for cgroup basic resource statistics implemented on top of
301 static void cgroup_base_stat_add(struct cgroup_base_stat *dst_bstat,
302 struct cgroup_base_stat *src_bstat)
304 dst_bstat->cputime.utime += src_bstat->cputime.utime;
305 dst_bstat->cputime.stime += src_bstat->cputime.stime;
306 dst_bstat->cputime.sum_exec_runtime += src_bstat->cputime.sum_exec_runtime;
309 static void cgroup_base_stat_sub(struct cgroup_base_stat *dst_bstat,
310 struct cgroup_base_stat *src_bstat)
312 dst_bstat->cputime.utime -= src_bstat->cputime.utime;
313 dst_bstat->cputime.stime -= src_bstat->cputime.stime;
314 dst_bstat->cputime.sum_exec_runtime -= src_bstat->cputime.sum_exec_runtime;
317 static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu)
319 struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
320 struct cgroup *parent = cgroup_parent(cgrp);
321 struct cgroup_base_stat cur, delta;
324 /* Root-level stats are sourced from system-wide CPU stats */
328 /* fetch the current per-cpu values */
330 seq = __u64_stats_fetch_begin(&rstatc->bsync);
331 cur.cputime = rstatc->bstat.cputime;
332 } while (__u64_stats_fetch_retry(&rstatc->bsync, seq));
334 /* propagate percpu delta to global */
336 cgroup_base_stat_sub(&delta, &rstatc->last_bstat);
337 cgroup_base_stat_add(&cgrp->bstat, &delta);
338 cgroup_base_stat_add(&rstatc->last_bstat, &delta);
340 /* propagate global delta to parent (unless that's root) */
341 if (cgroup_parent(parent)) {
343 cgroup_base_stat_sub(&delta, &cgrp->last_bstat);
344 cgroup_base_stat_add(&parent->bstat, &delta);
345 cgroup_base_stat_add(&cgrp->last_bstat, &delta);
349 static struct cgroup_rstat_cpu *
350 cgroup_base_stat_cputime_account_begin(struct cgroup *cgrp, unsigned long *flags)
352 struct cgroup_rstat_cpu *rstatc;
354 rstatc = get_cpu_ptr(cgrp->rstat_cpu);
355 *flags = u64_stats_update_begin_irqsave(&rstatc->bsync);
359 static void cgroup_base_stat_cputime_account_end(struct cgroup *cgrp,
360 struct cgroup_rstat_cpu *rstatc,
363 u64_stats_update_end_irqrestore(&rstatc->bsync, flags);
364 cgroup_rstat_updated(cgrp, smp_processor_id());
368 void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec)
370 struct cgroup_rstat_cpu *rstatc;
373 rstatc = cgroup_base_stat_cputime_account_begin(cgrp, &flags);
374 rstatc->bstat.cputime.sum_exec_runtime += delta_exec;
375 cgroup_base_stat_cputime_account_end(cgrp, rstatc, flags);
378 void __cgroup_account_cputime_field(struct cgroup *cgrp,
379 enum cpu_usage_stat index, u64 delta_exec)
381 struct cgroup_rstat_cpu *rstatc;
384 rstatc = cgroup_base_stat_cputime_account_begin(cgrp, &flags);
389 rstatc->bstat.cputime.utime += delta_exec;
393 case CPUTIME_SOFTIRQ:
394 rstatc->bstat.cputime.stime += delta_exec;
400 cgroup_base_stat_cputime_account_end(cgrp, rstatc, flags);
404 * compute the cputime for the root cgroup by getting the per cpu data
405 * at a global level, then categorizing the fields in a manner consistent
406 * with how it is done by __cgroup_account_cputime_field for each bit of
407 * cpu time attributed to a cgroup.
409 static void root_cgroup_cputime(struct task_cputime *cputime)
415 cputime->sum_exec_runtime = 0;
416 for_each_possible_cpu(i) {
417 struct kernel_cpustat kcpustat;
418 u64 *cpustat = kcpustat.cpustat;
422 kcpustat_cpu_fetch(&kcpustat, i);
424 user += cpustat[CPUTIME_USER];
425 user += cpustat[CPUTIME_NICE];
426 cputime->utime += user;
428 sys += cpustat[CPUTIME_SYSTEM];
429 sys += cpustat[CPUTIME_IRQ];
430 sys += cpustat[CPUTIME_SOFTIRQ];
431 cputime->stime += sys;
433 cputime->sum_exec_runtime += user;
434 cputime->sum_exec_runtime += sys;
435 cputime->sum_exec_runtime += cpustat[CPUTIME_STEAL];
439 void cgroup_base_stat_cputime_show(struct seq_file *seq)
441 struct cgroup *cgrp = seq_css(seq)->cgroup;
442 u64 usage, utime, stime;
443 struct task_cputime cputime;
445 if (cgroup_parent(cgrp)) {
446 cgroup_rstat_flush_hold(cgrp);
447 usage = cgrp->bstat.cputime.sum_exec_runtime;
448 cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
450 cgroup_rstat_flush_release();
452 root_cgroup_cputime(&cputime);
453 usage = cputime.sum_exec_runtime;
454 utime = cputime.utime;
455 stime = cputime.stime;
458 do_div(usage, NSEC_PER_USEC);
459 do_div(utime, NSEC_PER_USEC);
460 do_div(stime, NSEC_PER_USEC);
462 seq_printf(seq, "usage_usec %llu\n"
464 "system_usec %llu\n",
465 usage, utime, stime);