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Release 4.15 kernel/cgroup/stat.c

Directory: kernel/cgroup
#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); }

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/** * 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); }

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/** * 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; }

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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; }

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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); }

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/* 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); } }

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/** * 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); }

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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; }

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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); }

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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); }

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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); }

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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); }

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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) { struct cgroup_cpu_stat *cstat = cgroup_cpu_stat(cgrp, cpu); cstat->updated_children = cgrp; u64_stats_init(&cstat->sync); } prev_cputime_init(&cgrp->stat.prev_cputime); return 0; }

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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; }

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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)); }

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Directory: kernel/cgroup
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