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-rw-r--r--kernel/cgroup/rstat.c541
1 files changed, 541 insertions, 0 deletions
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
new file mode 100644
index 0000000000..d80d7a6081
--- /dev/null
+++ b/kernel/cgroup/rstat.c
@@ -0,0 +1,541 @@
+// 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)
+ __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);
+
+ /* play nice and yield if necessary */
+ if (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);
+ spin_unlock_irq(&cgroup_rstat_lock);
+}
+
+/**
+ * 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);
+}
+
+/**
+ * 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_rstat_cpu *prstatc;
+ 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 per-cpu delta to cgroup and per-cpu global statistics */
+ cgroup_base_stat_sub(&delta, &rstatc->last_bstat);
+ cgroup_base_stat_add(&cgrp->bstat, &delta);
+ cgroup_base_stat_add(&rstatc->last_bstat, &delta);
+ cgroup_base_stat_add(&rstatc->subtree_bstat, &delta);
+
+ /* propagate cgroup and per-cpu 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);
+
+ delta = rstatc->subtree_bstat;
+ prstatc = cgroup_rstat_cpu(parent, cpu);
+ cgroup_base_stat_sub(&delta, &rstatc->last_subtree_bstat);
+ cgroup_base_stat_add(&prstatc->subtree_bstat, &delta);
+ cgroup_base_stat_add(&rstatc->last_subtree_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;
+
+ memset(bstat, 0, sizeof(*bstat));
+ 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);