1 #include "cgroup-internal.h"
3 #include <linux/sched/cputime.h>
5 static DEFINE_MUTEX(cgroup_stat_mutex);
6 static DEFINE_PER_CPU(raw_spinlock_t, cgroup_cpu_stat_lock);
8 static struct cgroup_cpu_stat *cgroup_cpu_stat(struct cgroup *cgrp, int cpu)
10 return per_cpu_ptr(cgrp->cpu_stat, cpu);
14 * cgroup_cpu_stat_updated - keep track of updated cpu_stat
15 * @cgrp: target cgroup
16 * @cpu: cpu on which cpu_stat was updated
18 * @cgrp's cpu_stat on @cpu was updated. Put it on the parent's matching
19 * cpu_stat->updated_children list. See the comment on top of
20 * cgroup_cpu_stat definition for details.
22 static void cgroup_cpu_stat_updated(struct cgroup *cgrp, int cpu)
24 raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_cpu_stat_lock, cpu);
25 struct cgroup *parent;
29 * Speculative already-on-list test. This may race leading to
30 * temporary inaccuracies, which is fine.
32 * Because @parent's updated_children is terminated with @parent
33 * instead of NULL, we can tell whether @cgrp is on the list by
34 * testing the next pointer for NULL.
36 if (cgroup_cpu_stat(cgrp, cpu)->updated_next)
39 raw_spin_lock_irqsave(cpu_lock, flags);
41 /* put @cgrp and all ancestors on the corresponding updated lists */
42 for (parent = cgroup_parent(cgrp); parent;
43 cgrp = parent, parent = cgroup_parent(cgrp)) {
44 struct cgroup_cpu_stat *cstat = cgroup_cpu_stat(cgrp, cpu);
45 struct cgroup_cpu_stat *pcstat = cgroup_cpu_stat(parent, cpu);
48 * Both additions and removals are bottom-up. If a cgroup
49 * is already in the tree, all ancestors are.
51 if (cstat->updated_next)
54 cstat->updated_next = pcstat->updated_children;
55 pcstat->updated_children = cgrp;
58 raw_spin_unlock_irqrestore(cpu_lock, flags);
62 * cgroup_cpu_stat_pop_updated - iterate and dismantle cpu_stat updated tree
63 * @pos: current position
64 * @root: root of the tree to traversal
67 * Walks the udpated cpu_stat tree on @cpu from @root. %NULL @pos starts
68 * the traversal and %NULL return indicates the end. During traversal,
69 * each returned cgroup is unlinked from the tree. Must be called with the
70 * matching cgroup_cpu_stat_lock held.
72 * The only ordering guarantee is that, for a parent and a child pair
73 * covered by a given traversal, if a child is visited, its parent is
74 * guaranteed to be visited afterwards.
76 static struct cgroup *cgroup_cpu_stat_pop_updated(struct cgroup *pos,
77 struct cgroup *root, int cpu)
79 struct cgroup_cpu_stat *cstat;
80 struct cgroup *parent;
86 * We're gonna walk down to the first leaf and visit/remove it. We
87 * can pick whatever unvisited node as the starting point.
92 pos = cgroup_parent(pos);
94 /* walk down to the first leaf */
96 cstat = cgroup_cpu_stat(pos, cpu);
97 if (cstat->updated_children == pos)
99 pos = cstat->updated_children;
103 * Unlink @pos from the tree. As the updated_children list is
104 * singly linked, we have to walk it to find the removal point.
105 * However, due to the way we traverse, @pos will be the first
106 * child in most cases. The only exception is @root.
108 parent = cgroup_parent(pos);
109 if (parent && cstat->updated_next) {
110 struct cgroup_cpu_stat *pcstat = cgroup_cpu_stat(parent, cpu);
111 struct cgroup_cpu_stat *ncstat;
112 struct cgroup **nextp;
114 nextp = &pcstat->updated_children;
116 ncstat = cgroup_cpu_stat(*nextp, cpu);
120 WARN_ON_ONCE(*nextp == parent);
121 nextp = &ncstat->updated_next;
124 *nextp = cstat->updated_next;
125 cstat->updated_next = NULL;
131 static void cgroup_stat_accumulate(struct cgroup_stat *dst_stat,
132 struct cgroup_stat *src_stat)
134 dst_stat->cputime.utime += src_stat->cputime.utime;
135 dst_stat->cputime.stime += src_stat->cputime.stime;
136 dst_stat->cputime.sum_exec_runtime += src_stat->cputime.sum_exec_runtime;
139 static void cgroup_cpu_stat_flush_one(struct cgroup *cgrp, int cpu)
141 struct cgroup *parent = cgroup_parent(cgrp);
142 struct cgroup_cpu_stat *cstat = cgroup_cpu_stat(cgrp, cpu);
143 struct task_cputime *last_cputime = &cstat->last_cputime;
144 struct task_cputime cputime;
145 struct cgroup_stat delta;
148 lockdep_assert_held(&cgroup_stat_mutex);
150 /* fetch the current per-cpu values */
152 seq = __u64_stats_fetch_begin(&cstat->sync);
153 cputime = cstat->cputime;
154 } while (__u64_stats_fetch_retry(&cstat->sync, seq));
156 /* accumulate the deltas to propgate */
157 delta.cputime.utime = cputime.utime - last_cputime->utime;
158 delta.cputime.stime = cputime.stime - last_cputime->stime;
159 delta.cputime.sum_exec_runtime = cputime.sum_exec_runtime -
160 last_cputime->sum_exec_runtime;
161 *last_cputime = cputime;
163 /* transfer the pending stat into delta */
164 cgroup_stat_accumulate(&delta, &cgrp->pending_stat);
165 memset(&cgrp->pending_stat, 0, sizeof(cgrp->pending_stat));
167 /* propagate delta into the global stat and the parent's pending */
168 cgroup_stat_accumulate(&cgrp->stat, &delta);
170 cgroup_stat_accumulate(&parent->pending_stat, &delta);
173 /* see cgroup_stat_flush() */
174 static void cgroup_stat_flush_locked(struct cgroup *cgrp)
178 lockdep_assert_held(&cgroup_stat_mutex);
180 for_each_possible_cpu(cpu) {
181 raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_cpu_stat_lock, cpu);
182 struct cgroup *pos = NULL;
184 raw_spin_lock_irq(cpu_lock);
185 while ((pos = cgroup_cpu_stat_pop_updated(pos, cgrp, cpu)))
186 cgroup_cpu_stat_flush_one(pos, cpu);
187 raw_spin_unlock_irq(cpu_lock);
192 * cgroup_stat_flush - flush stats in @cgrp's subtree
193 * @cgrp: target cgroup
195 * Collect all per-cpu stats in @cgrp's subtree into the global counters
196 * and propagate them upwards. After this function returns, all cgroups in
197 * the subtree have up-to-date ->stat.
199 * This also gets all cgroups in the subtree including @cgrp off the
200 * ->updated_children lists.
202 void cgroup_stat_flush(struct cgroup *cgrp)
204 mutex_lock(&cgroup_stat_mutex);
205 cgroup_stat_flush_locked(cgrp);
206 mutex_unlock(&cgroup_stat_mutex);
209 static struct cgroup_cpu_stat *cgroup_cpu_stat_account_begin(struct cgroup *cgrp)
211 struct cgroup_cpu_stat *cstat;
213 cstat = get_cpu_ptr(cgrp->cpu_stat);
214 u64_stats_update_begin(&cstat->sync);
218 static void cgroup_cpu_stat_account_end(struct cgroup *cgrp,
219 struct cgroup_cpu_stat *cstat)
221 u64_stats_update_end(&cstat->sync);
222 cgroup_cpu_stat_updated(cgrp, smp_processor_id());
226 void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec)
228 struct cgroup_cpu_stat *cstat;
230 cstat = cgroup_cpu_stat_account_begin(cgrp);
231 cstat->cputime.sum_exec_runtime += delta_exec;
232 cgroup_cpu_stat_account_end(cgrp, cstat);
235 void __cgroup_account_cputime_field(struct cgroup *cgrp,
236 enum cpu_usage_stat index, u64 delta_exec)
238 struct cgroup_cpu_stat *cstat;
240 cstat = cgroup_cpu_stat_account_begin(cgrp);
245 cstat->cputime.utime += delta_exec;
249 case CPUTIME_SOFTIRQ:
250 cstat->cputime.stime += delta_exec;
256 cgroup_cpu_stat_account_end(cgrp, cstat);
259 void cgroup_stat_show_cputime(struct seq_file *seq)
261 struct cgroup *cgrp = seq_css(seq)->cgroup;
262 u64 usage, utime, stime;
264 if (!cgroup_parent(cgrp))
267 mutex_lock(&cgroup_stat_mutex);
269 cgroup_stat_flush_locked(cgrp);
271 usage = cgrp->stat.cputime.sum_exec_runtime;
272 cputime_adjust(&cgrp->stat.cputime, &cgrp->stat.prev_cputime,
275 mutex_unlock(&cgroup_stat_mutex);
277 do_div(usage, NSEC_PER_USEC);
278 do_div(utime, NSEC_PER_USEC);
279 do_div(stime, NSEC_PER_USEC);
281 seq_printf(seq, "usage_usec %llu\n"
283 "system_usec %llu\n",
284 usage, utime, stime);
287 int cgroup_stat_init(struct cgroup *cgrp)
291 /* the root cgrp has cpu_stat preallocated */
292 if (!cgrp->cpu_stat) {
293 cgrp->cpu_stat = alloc_percpu(struct cgroup_cpu_stat);
298 /* ->updated_children list is self terminated */
299 for_each_possible_cpu(cpu)
300 cgroup_cpu_stat(cgrp, cpu)->updated_children = cgrp;
302 prev_cputime_init(&cgrp->stat.prev_cputime);
307 void cgroup_stat_exit(struct cgroup *cgrp)
311 cgroup_stat_flush(cgrp);
314 for_each_possible_cpu(cpu) {
315 struct cgroup_cpu_stat *cstat = cgroup_cpu_stat(cgrp, cpu);
317 if (WARN_ON_ONCE(cstat->updated_children != cgrp) ||
318 WARN_ON_ONCE(cstat->updated_next))
322 free_percpu(cgrp->cpu_stat);
323 cgrp->cpu_stat = NULL;
326 void __init cgroup_stat_boot(void)
330 for_each_possible_cpu(cpu)
331 raw_spin_lock_init(per_cpu_ptr(&cgroup_cpu_stat_lock, cpu));
333 BUG_ON(cgroup_stat_init(&cgrp_dfl_root.cgrp));