| // SPDX-License-Identifier: GPL-2.0-only |
| #include "cgroup-internal.h" |
| |
| #include <linux/sched/cputime.h> |
| |
| #include <linux/bpf.h> |
| #include <linux/btf.h> |
| #include <linux/btf_ids.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. |
| */ |
| __bpf_kfunc void cgroup_rstat_updated(struct cgroup *cgrp, int cpu) |
| { |
| raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu); |
| 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 (data_race(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 */ |
| while (true) { |
| struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu); |
| struct cgroup *parent = cgroup_parent(cgrp); |
| struct cgroup_rstat_cpu *prstatc; |
| |
| /* |
| * Both additions and removals are bottom-up. If a cgroup |
| * is already in the tree, all ancestors are. |
| */ |
| if (rstatc->updated_next) |
| break; |
| |
| /* Root has no parent to link it to, but mark it busy */ |
| if (!parent) { |
| rstatc->updated_next = cgrp; |
| break; |
| } |
| |
| prstatc = cgroup_rstat_cpu(parent, cpu); |
| rstatc->updated_next = prstatc->updated_children; |
| prstatc->updated_children = cgrp; |
| |
| cgrp = parent; |
| } |
| |
| raw_spin_unlock_irqrestore(cpu_lock, flags); |
| } |
| |
| /** |
| * 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 updated 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; |
| 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; |
| /* return NULL if this subtree is not on-list */ |
| if (!cgroup_rstat_cpu(pos, cpu)->updated_next) |
| return NULL; |
| } 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. |
| */ |
| parent = cgroup_parent(pos); |
| if (parent) { |
| struct cgroup_rstat_cpu *prstatc; |
| struct cgroup **nextp; |
| |
| prstatc = cgroup_rstat_cpu(parent, cpu); |
| nextp = &prstatc->updated_children; |
| while (*nextp != pos) { |
| struct cgroup_rstat_cpu *nrstatc; |
| |
| nrstatc = cgroup_rstat_cpu(*nextp, cpu); |
| WARN_ON_ONCE(*nextp == parent); |
| nextp = &nrstatc->updated_next; |
| } |
| *nextp = rstatc->updated_next; |
| } |
| |
| rstatc->updated_next = NULL; |
| return pos; |
| } |
| |
| /* |
| * A hook for bpf stat collectors to attach to and flush their stats. |
| * Together with providing bpf kfuncs for cgroup_rstat_updated() and |
| * cgroup_rstat_flush(), this enables a complete workflow where bpf progs that |
| * collect cgroup stats can integrate with rstat for efficient flushing. |
| * |
| * A static noinline declaration here could cause the compiler to optimize away |
| * the function. A global noinline declaration will keep the definition, but may |
| * optimize away the callsite. Therefore, __weak is needed to ensure that the |
| * call is still emitted, by telling the compiler that we don't know what the |
| * function might eventually be. |
| * |
| * __diag_* below are needed to dismiss the missing prototype warning. |
| */ |
| __diag_push(); |
| __diag_ignore_all("-Wmissing-prototypes", |
| "kfuncs which will be used in BPF programs"); |
| |
| __weak noinline void bpf_rstat_flush(struct cgroup *cgrp, |
| struct cgroup *parent, int cpu) |
| { |
| } |
| |
| __diag_pop(); |
| |
| /* 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; |
| unsigned long flags; |
| |
| /* |
| * The _irqsave() is needed because cgroup_rstat_lock is |
| * spinlock_t which is a sleeping lock on PREEMPT_RT. Acquiring |
| * this lock with the _irq() suffix only disables interrupts on |
| * a non-PREEMPT_RT kernel. The raw_spinlock_t below disables |
| * interrupts on both configurations. The _irqsave() ensures |
| * that interrupts are always disabled and later restored. |
| */ |
| raw_spin_lock_irqsave(cpu_lock, flags); |
| while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu))) { |
| struct cgroup_subsys_state *css; |
| |
| cgroup_base_stat_flush(pos, cpu); |
| bpf_rstat_flush(pos, cgroup_parent(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_irqrestore(cpu_lock, flags); |
| |
| /* 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. |
| */ |
| __bpf_kfunc 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_hold - 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)); |
| } |
| |
| /* |
| * Functions for cgroup basic resource statistics implemented on top of |
| * rstat. |
| */ |
| static void cgroup_base_stat_add(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; |
| #ifdef CONFIG_SCHED_CORE |
| dst_bstat->forceidle_sum += src_bstat->forceidle_sum; |
| #endif |
| } |
| |
| static void cgroup_base_stat_sub(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; |
| #ifdef CONFIG_SCHED_CORE |
| dst_bstat->forceidle_sum -= src_bstat->forceidle_sum; |
| #endif |
| } |
| |
| static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu) |
| { |
| struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu); |
| struct cgroup *parent = cgroup_parent(cgrp); |
| struct cgroup_base_stat delta; |
| unsigned seq; |
| |
| /* Root-level stats are sourced from system-wide CPU stats */ |
| if (!parent) |
| return; |
| |
| /* fetch the current per-cpu values */ |
| do { |
| seq = __u64_stats_fetch_begin(&rstatc->bsync); |
| delta = rstatc->bstat; |
| } while (__u64_stats_fetch_retry(&rstatc->bsync, seq)); |
| |
| /* propagate percpu delta to global */ |
| cgroup_base_stat_sub(&delta, &rstatc->last_bstat); |
| cgroup_base_stat_add(&cgrp->bstat, &delta); |
| cgroup_base_stat_add(&rstatc->last_bstat, &delta); |
| |
| /* propagate global delta to parent (unless that's root) */ |
| if (cgroup_parent(parent)) { |
| delta = cgrp->bstat; |
| cgroup_base_stat_sub(&delta, &cgrp->last_bstat); |
| cgroup_base_stat_add(&parent->bstat, &delta); |
| cgroup_base_stat_add(&cgrp->last_bstat, &delta); |
| } |
| } |
| |
| static struct cgroup_rstat_cpu * |
| cgroup_base_stat_cputime_account_begin(struct cgroup *cgrp, unsigned long *flags) |
| { |
| struct cgroup_rstat_cpu *rstatc; |
| |
| rstatc = get_cpu_ptr(cgrp->rstat_cpu); |
| *flags = u64_stats_update_begin_irqsave(&rstatc->bsync); |
| return rstatc; |
| } |
| |
| static void cgroup_base_stat_cputime_account_end(struct cgroup *cgrp, |
| struct cgroup_rstat_cpu *rstatc, |
| unsigned long flags) |
| { |
| u64_stats_update_end_irqrestore(&rstatc->bsync, flags); |
| 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; |
| unsigned long flags; |
| |
| rstatc = cgroup_base_stat_cputime_account_begin(cgrp, &flags); |
| rstatc->bstat.cputime.sum_exec_runtime += delta_exec; |
| cgroup_base_stat_cputime_account_end(cgrp, rstatc, flags); |
| } |
| |
| void __cgroup_account_cputime_field(struct cgroup *cgrp, |
| enum cpu_usage_stat index, u64 delta_exec) |
| { |
| struct cgroup_rstat_cpu *rstatc; |
| unsigned long flags; |
| |
| rstatc = cgroup_base_stat_cputime_account_begin(cgrp, &flags); |
| |
| 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; |
| #ifdef CONFIG_SCHED_CORE |
| case CPUTIME_FORCEIDLE: |
| rstatc->bstat.forceidle_sum += delta_exec; |
| break; |
| #endif |
| default: |
| break; |
| } |
| |
| cgroup_base_stat_cputime_account_end(cgrp, rstatc, flags); |
| } |
| |
| /* |
| * compute the cputime for the root cgroup by getting the per cpu data |
| * at a global level, then categorizing the fields in a manner consistent |
| * with how it is done by __cgroup_account_cputime_field for each bit of |
| * cpu time attributed to a cgroup. |
| */ |
| static void root_cgroup_cputime(struct cgroup_base_stat *bstat) |
| { |
| struct task_cputime *cputime = &bstat->cputime; |
| int i; |
| |
| cputime->stime = 0; |
| cputime->utime = 0; |
| cputime->sum_exec_runtime = 0; |
| for_each_possible_cpu(i) { |
| struct kernel_cpustat kcpustat; |
| u64 *cpustat = kcpustat.cpustat; |
| u64 user = 0; |
| u64 sys = 0; |
| |
| kcpustat_cpu_fetch(&kcpustat, i); |
| |
| user += cpustat[CPUTIME_USER]; |
| user += cpustat[CPUTIME_NICE]; |
| cputime->utime += user; |
| |
| sys += cpustat[CPUTIME_SYSTEM]; |
| sys += cpustat[CPUTIME_IRQ]; |
| sys += cpustat[CPUTIME_SOFTIRQ]; |
| cputime->stime += sys; |
| |
| cputime->sum_exec_runtime += user; |
| cputime->sum_exec_runtime += sys; |
| cputime->sum_exec_runtime += cpustat[CPUTIME_STEAL]; |
| |
| #ifdef CONFIG_SCHED_CORE |
| bstat->forceidle_sum += cpustat[CPUTIME_FORCEIDLE]; |
| #endif |
| } |
| } |
| |
| void cgroup_base_stat_cputime_show(struct seq_file *seq) |
| { |
| struct cgroup *cgrp = seq_css(seq)->cgroup; |
| u64 usage, utime, stime; |
| struct cgroup_base_stat bstat; |
| #ifdef CONFIG_SCHED_CORE |
| u64 forceidle_time; |
| #endif |
| |
| if (cgroup_parent(cgrp)) { |
| cgroup_rstat_flush_hold(cgrp); |
| usage = cgrp->bstat.cputime.sum_exec_runtime; |
| cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime, |
| &utime, &stime); |
| #ifdef CONFIG_SCHED_CORE |
| forceidle_time = cgrp->bstat.forceidle_sum; |
| #endif |
| cgroup_rstat_flush_release(); |
| } else { |
| root_cgroup_cputime(&bstat); |
| usage = bstat.cputime.sum_exec_runtime; |
| utime = bstat.cputime.utime; |
| stime = bstat.cputime.stime; |
| #ifdef CONFIG_SCHED_CORE |
| forceidle_time = bstat.forceidle_sum; |
| #endif |
| } |
| |
| do_div(usage, NSEC_PER_USEC); |
| do_div(utime, NSEC_PER_USEC); |
| do_div(stime, NSEC_PER_USEC); |
| #ifdef CONFIG_SCHED_CORE |
| do_div(forceidle_time, NSEC_PER_USEC); |
| #endif |
| |
| seq_printf(seq, "usage_usec %llu\n" |
| "user_usec %llu\n" |
| "system_usec %llu\n", |
| usage, utime, stime); |
| |
| #ifdef CONFIG_SCHED_CORE |
| seq_printf(seq, "core_sched.force_idle_usec %llu\n", forceidle_time); |
| #endif |
| } |
| |
| /* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */ |
| BTF_SET8_START(bpf_rstat_kfunc_ids) |
| BTF_ID_FLAGS(func, cgroup_rstat_updated) |
| BTF_ID_FLAGS(func, cgroup_rstat_flush, KF_SLEEPABLE) |
| BTF_SET8_END(bpf_rstat_kfunc_ids) |
| |
| static const struct btf_kfunc_id_set bpf_rstat_kfunc_set = { |
| .owner = THIS_MODULE, |
| .set = &bpf_rstat_kfunc_ids, |
| }; |
| |
| static int __init bpf_rstat_kfunc_init(void) |
| { |
| return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, |
| &bpf_rstat_kfunc_set); |
| } |
| late_initcall(bpf_rstat_kfunc_init); |