#include <linux/refcount.h>
#include <linux/percpu-refcount.h>
#include <linux/percpu-rwsem.h>
+#include <linux/u64_stats_sync.h>
#include <linux/workqueue.h>
#include <linux/bpf-cgroup.h>
struct rcu_head rcu_head;
};
+/*
+ * cgroup basic resource usage statistics. Accounting is done per-cpu in
+ * cgroup_cpu_stat which is then lazily propagated up the hierarchy on
+ * reads.
+ *
+ * When a stat gets updated, the cgroup_cpu_stat and its ancestors are
+ * linked into the updated tree. On the following read, propagation only
+ * considers and consumes the updated tree. This makes reading O(the
+ * number of descendants which have been active since last read) instead of
+ * O(the total number of descendants).
+ *
+ * This is important because there can be a lot of (draining) cgroups which
+ * aren't active and stat may be read frequently. The combination can
+ * become very expensive. By propagating selectively, increasing reading
+ * frequency decreases the cost of each read.
+ */
+struct cgroup_cpu_stat {
+ /*
+ * ->sync protects all the current counters. These are the only
+ * fields which get updated in the hot path.
+ */
+ struct u64_stats_sync sync;
+ struct task_cputime cputime;
+
+ /*
+ * Snapshots at the last reading. These are used to calculate the
+ * deltas to propagate to the global counters.
+ */
+ struct task_cputime last_cputime;
+
+ /*
+ * Child cgroups with stat updates on this cpu since the last read
+ * are linked on the parent's ->updated_children through
+ * ->updated_next.
+ *
+ * In addition to being more compact, singly-linked list pointing
+ * to the cgroup makes it unnecessary for each per-cpu struct to
+ * point back to the associated cgroup.
+ *
+ * Protected by per-cpu cgroup_cpu_stat_lock.
+ */
+ struct cgroup *updated_children; /* terminated by self cgroup */
+ struct cgroup *updated_next; /* NULL iff not on the list */
+};
+
+struct cgroup_stat {
+ /* per-cpu statistics are collected into the folowing global counters */
+ struct task_cputime cputime;
+ struct prev_cputime prev_cputime;
+};
+
struct cgroup {
/* self css with NULL ->ss, points back to this cgroup */
struct cgroup_subsys_state self;
*/
struct cgroup *dom_cgrp;
+ /* cgroup basic resource statistics */
+ struct cgroup_cpu_stat __percpu *cpu_stat;
+ struct cgroup_stat pending_stat; /* pending from children */
+ struct cgroup_stat stat;
+
/*
* list of pidlists, up to two for each namespace (one for procs, one
* for tasks); created on demand.
--- /dev/null
+#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, const char *prefix)
+{
+ 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, "%susage_usec %llu\n"
+ "%suser_usec %llu\n"
+ "%ssystem_usec %llu\n",
+ prefix, usage, prefix, utime, prefix, 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));
+}
projects / openwrt / staging / blogic.git / commitdiff