| // SPDX-License-Identifier: GPL-2.0-only |
| #include "cgroup-internal.h" |
| |
| #include <linux/sched/cputime.h> |
| |
| static DEFINE_SPINLOCK(cgroup_rstat_lock); |
| static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock); |
| |
| static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu); |
| |
| static struct cgroup_rstat_cpu *cgroup_rstat_cpu(struct cgroup *cgrp, int cpu) |
| { |
| return per_cpu_ptr(cgrp->rstat_cpu, cpu); |
| } |
| |
| /** |
| * cgroup_rstat_updated - keep track of updated rstat_cpu |
| * @cgrp: target cgroup |
| * @cpu: cpu on which rstat_cpu was updated |
| * |
| * @cgrp's rstat_cpu on @cpu was updated. Put it on the parent's matching |
| * rstat_cpu->updated_children list. See the comment on top of |
| * cgroup_rstat_cpu definition for details. |
| */ |
| void cgroup_rstat_updated(struct cgroup *cgrp, int cpu) |
| { |
| raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu); |
| struct cgroup *parent; |
| unsigned long flags; |
| |
| /* nothing to do for root */ |
| if (!cgroup_parent(cgrp)) |
| return; |
| |
| /* |
| * Paired with the one in cgroup_rstat_cpu_pop_upated(). Either we |
| * see NULL updated_next or they see our updated stat. |
| */ |
| smp_mb(); |
| |
| /* |
| * 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_rstat_cpu(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_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu); |
| struct cgroup_rstat_cpu *prstatc = cgroup_rstat_cpu(parent, cpu); |
| |
| /* |
| * Both additions and removals are bottom-up. If a cgroup |
| * is already in the tree, all ancestors are. |
| */ |
| if (rstatc->updated_next) |
| break; |
| |
| rstatc->updated_next = prstatc->updated_children; |
| prstatc->updated_children = cgrp; |
| } |
| |
| raw_spin_unlock_irqrestore(cpu_lock, flags); |
| } |
| EXPORT_SYMBOL_GPL(cgroup_rstat_updated); |
| |
| /** |
| * cgroup_rstat_cpu_pop_updated - iterate and dismantle rstat_cpu updated tree |
| * @pos: current position |
| * @root: root of the tree to traversal |
| * @cpu: target cpu |
| * |
| * Walks the udpated rstat_cpu 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_rstat_cpu_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_rstat_cpu_pop_updated(struct cgroup *pos, |
| struct cgroup *root, int cpu) |
| { |
| struct cgroup_rstat_cpu *rstatc; |
| |
| 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) { |
| rstatc = cgroup_rstat_cpu(pos, cpu); |
| if (rstatc->updated_children == pos) |
| break; |
| pos = rstatc->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. |
| */ |
| if (rstatc->updated_next) { |
| struct cgroup *parent = cgroup_parent(pos); |
| struct cgroup_rstat_cpu *prstatc = cgroup_rstat_cpu(parent, cpu); |
| struct cgroup_rstat_cpu *nrstatc; |
| struct cgroup **nextp; |
| |
| nextp = &prstatc->updated_children; |
| while (true) { |
| nrstatc = cgroup_rstat_cpu(*nextp, cpu); |
| if (*nextp == pos) |
| break; |
| |
| WARN_ON_ONCE(*nextp == parent); |
| nextp = &nrstatc->updated_next; |
| } |
| |
| *nextp = rstatc->updated_next; |
| rstatc->updated_next = NULL; |
| |
| /* |
| * Paired with the one in cgroup_rstat_cpu_updated(). |
| * Either they see NULL updated_next or we see their |
| * updated stat. |
| */ |
| smp_mb(); |
| |
| return pos; |
| } |
| |
| /* only happens for @root */ |
| return NULL; |
| } |
| |
| /* see cgroup_rstat_flush() */ |
| static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep) |
| __releases(&cgroup_rstat_lock) __acquires(&cgroup_rstat_lock) |
| { |
| int cpu; |
| |
| lockdep_assert_held(&cgroup_rstat_lock); |
| |
| for_each_possible_cpu(cpu) { |
| raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, |
| cpu); |
| struct cgroup *pos = NULL; |
| |
| raw_spin_lock(cpu_lock); |
| while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu))) { |
| struct cgroup_subsys_state *css; |
| |
| cgroup_base_stat_flush(pos, cpu); |
| |
| rcu_read_lock(); |
| list_for_each_entry_rcu(css, &pos->rstat_css_list, |
| rstat_css_node) |
| css->ss->css_rstat_flush(css, cpu); |
| rcu_read_unlock(); |
| } |
| raw_spin_unlock(cpu_lock); |
| |
| /* if @may_sleep, play nice and yield if necessary */ |
| if (may_sleep && (need_resched() || |
| spin_needbreak(&cgroup_rstat_lock))) { |
| spin_unlock_irq(&cgroup_rstat_lock); |
| if (!cond_resched()) |
| cpu_relax(); |
| spin_lock_irq(&cgroup_rstat_lock); |
| } |
| } |
| } |
| |
| /** |
| * cgroup_rstat_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. |
| * |
| * This function may block. |
| */ |
| void cgroup_rstat_flush(struct cgroup *cgrp) |
| { |
| might_sleep(); |
| |
| spin_lock_irq(&cgroup_rstat_lock); |
| cgroup_rstat_flush_locked(cgrp, true); |
| spin_unlock_irq(&cgroup_rstat_lock); |
| } |
| |
| /** |
| * cgroup_rstat_flush_irqsafe - irqsafe version of cgroup_rstat_flush() |
| * @cgrp: target cgroup |
| * |
| * This function can be called from any context. |
| */ |
| void cgroup_rstat_flush_irqsafe(struct cgroup *cgrp) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&cgroup_rstat_lock, flags); |
| cgroup_rstat_flush_locked(cgrp, false); |
| spin_unlock_irqrestore(&cgroup_rstat_lock, flags); |
| } |
| |
| /** |
| * cgroup_rstat_flush_begin - flush stats in @cgrp's subtree and hold |
| * @cgrp: target cgroup |
| * |
| * Flush stats in @cgrp's subtree and prevent further flushes. Must be |
| * paired with cgroup_rstat_flush_release(). |
| * |
| * This function may block. |
| */ |
| void cgroup_rstat_flush_hold(struct cgroup *cgrp) |
| __acquires(&cgroup_rstat_lock) |
| { |
| might_sleep(); |
| spin_lock_irq(&cgroup_rstat_lock); |
| cgroup_rstat_flush_locked(cgrp, true); |
| } |
| |
| /** |
| * cgroup_rstat_flush_release - release cgroup_rstat_flush_hold() |
| */ |
| void cgroup_rstat_flush_release(void) |
| __releases(&cgroup_rstat_lock) |
| { |
| spin_unlock_irq(&cgroup_rstat_lock); |
| } |
| |
| int cgroup_rstat_init(struct cgroup *cgrp) |
| { |
| int cpu; |
| |
| /* the root cgrp has rstat_cpu preallocated */ |
| if (!cgrp->rstat_cpu) { |
| cgrp->rstat_cpu = alloc_percpu(struct cgroup_rstat_cpu); |
| if (!cgrp->rstat_cpu) |
| return -ENOMEM; |
| } |
| |
| /* ->updated_children list is self terminated */ |
| for_each_possible_cpu(cpu) { |
| struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu); |
| |
| rstatc->updated_children = cgrp; |
| u64_stats_init(&rstatc->bsync); |
| } |
| |
| return 0; |
| } |
| |
| void cgroup_rstat_exit(struct cgroup *cgrp) |
| { |
| int cpu; |
| |
| cgroup_rstat_flush(cgrp); |
| |
| /* sanity check */ |
| for_each_possible_cpu(cpu) { |
| struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu); |
| |
| if (WARN_ON_ONCE(rstatc->updated_children != cgrp) || |
| WARN_ON_ONCE(rstatc->updated_next)) |
| return; |
| } |
| |
| free_percpu(cgrp->rstat_cpu); |
| cgrp->rstat_cpu = NULL; |
| } |
| |
| void __init cgroup_rstat_boot(void) |
| { |
| int cpu; |
| |
| for_each_possible_cpu(cpu) |
| raw_spin_lock_init(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu)); |
| |
| BUG_ON(cgroup_rstat_init(&cgrp_dfl_root.cgrp)); |
| } |
| |
| /* |
| * Functions for cgroup basic resource statistics implemented on top of |
| * rstat. |
| */ |
| static void cgroup_base_stat_accumulate(struct cgroup_base_stat *dst_bstat, |
| struct cgroup_base_stat *src_bstat) |
| { |
| dst_bstat->cputime.utime += src_bstat->cputime.utime; |
| dst_bstat->cputime.stime += src_bstat->cputime.stime; |
| dst_bstat->cputime.sum_exec_runtime += src_bstat->cputime.sum_exec_runtime; |
| } |
| |
| static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu) |
| { |
| struct cgroup *parent = cgroup_parent(cgrp); |
| struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu); |
| struct task_cputime *last_cputime = &rstatc->last_bstat.cputime; |
| struct task_cputime cputime; |
| struct cgroup_base_stat delta; |
| unsigned seq; |
| |
| /* fetch the current per-cpu values */ |
| do { |
| seq = __u64_stats_fetch_begin(&rstatc->bsync); |
| cputime = rstatc->bstat.cputime; |
| } while (__u64_stats_fetch_retry(&rstatc->bsync, seq)); |
| |
| /* calculate the delta 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_base_stat_accumulate(&delta, &cgrp->pending_bstat); |
| memset(&cgrp->pending_bstat, 0, sizeof(cgrp->pending_bstat)); |
| |
| /* propagate delta into the global stat and the parent's pending */ |
| cgroup_base_stat_accumulate(&cgrp->bstat, &delta); |
| if (parent) |
| cgroup_base_stat_accumulate(&parent->pending_bstat, &delta); |
| } |
| |
| static struct cgroup_rstat_cpu * |
| cgroup_base_stat_cputime_account_begin(struct cgroup *cgrp) |
| { |
| struct cgroup_rstat_cpu *rstatc; |
| |
| rstatc = get_cpu_ptr(cgrp->rstat_cpu); |
| u64_stats_update_begin(&rstatc->bsync); |
| return rstatc; |
| } |
| |
| static void cgroup_base_stat_cputime_account_end(struct cgroup *cgrp, |
| struct cgroup_rstat_cpu *rstatc) |
| { |
| u64_stats_update_end(&rstatc->bsync); |
| cgroup_rstat_updated(cgrp, smp_processor_id()); |
| put_cpu_ptr(rstatc); |
| } |
| |
| void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec) |
| { |
| struct cgroup_rstat_cpu *rstatc; |
| |
| rstatc = cgroup_base_stat_cputime_account_begin(cgrp); |
| rstatc->bstat.cputime.sum_exec_runtime += delta_exec; |
| cgroup_base_stat_cputime_account_end(cgrp, rstatc); |
| } |
| |
| void __cgroup_account_cputime_field(struct cgroup *cgrp, |
| enum cpu_usage_stat index, u64 delta_exec) |
| { |
| struct cgroup_rstat_cpu *rstatc; |
| |
| rstatc = cgroup_base_stat_cputime_account_begin(cgrp); |
| |
| switch (index) { |
| case CPUTIME_USER: |
| case CPUTIME_NICE: |
| rstatc->bstat.cputime.utime += delta_exec; |
| break; |
| case CPUTIME_SYSTEM: |
| case CPUTIME_IRQ: |
| case CPUTIME_SOFTIRQ: |
| rstatc->bstat.cputime.stime += delta_exec; |
| break; |
| default: |
| break; |
| } |
| |
| cgroup_base_stat_cputime_account_end(cgrp, rstatc); |
| } |
| |
| void cgroup_base_stat_cputime_show(struct seq_file *seq) |
| { |
| struct cgroup *cgrp = seq_css(seq)->cgroup; |
| u64 usage, utime, stime; |
| |
| if (!cgroup_parent(cgrp)) |
| return; |
| |
| cgroup_rstat_flush_hold(cgrp); |
| usage = cgrp->bstat.cputime.sum_exec_runtime; |
| cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime, &utime, &stime); |
| cgroup_rstat_flush_release(); |
| |
| 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); |
| } |