diff options
Diffstat (limited to '')
| -rw-r--r-- | tools/perf/util/bpf_skel/bperf_cgroup.bpf.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/tools/perf/util/bpf_skel/bperf_cgroup.bpf.c b/tools/perf/util/bpf_skel/bperf_cgroup.bpf.c new file mode 100644 index 000000000000..6a438e0102c5 --- /dev/null +++ b/tools/perf/util/bpf_skel/bperf_cgroup.bpf.c @@ -0,0 +1,227 @@ +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +// Copyright (c) 2021 Facebook +// Copyright (c) 2021 Google +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> +#include <bpf/bpf_core_read.h> + +#define MAX_LEVELS 10 // max cgroup hierarchy level: arbitrary +#define MAX_EVENTS 32 // max events per cgroup: arbitrary + +// NOTE: many of map and global data will be modified before loading +// from the userspace (perf tool) using the skeleton helpers. + +// single set of global perf events to measure +struct { + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(int)); + __uint(max_entries, 1); +} events SEC(".maps"); + +// from cgroup id to event index +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(key_size, sizeof(__u64)); + __uint(value_size, sizeof(__u32)); + __uint(max_entries, 1); +} cgrp_idx SEC(".maps"); + +// per-cpu event snapshots to calculate delta +struct { + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(struct bpf_perf_event_value)); +} prev_readings SEC(".maps"); + +// aggregated event values for each cgroup (per-cpu) +// will be read from the user-space +struct { + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(struct bpf_perf_event_value)); +} cgrp_readings SEC(".maps"); + +/* new kernel cgroup definition */ +struct cgroup___new { + int level; + struct cgroup *ancestors[]; +} __attribute__((preserve_access_index)); + +/* old kernel cgroup definition */ +struct cgroup___old { + int level; + u64 ancestor_ids[]; +} __attribute__((preserve_access_index)); + +const volatile __u32 num_events = 1; +const volatile __u32 num_cpus = 1; + +int enabled = 0; +int use_cgroup_v2 = 0; +int perf_subsys_id = -1; + +static inline __u64 get_cgroup_v1_ancestor_id(struct cgroup *cgrp, int level) +{ + /* recast pointer to capture new type for compiler */ + struct cgroup___new *cgrp_new = (void *)cgrp; + + if (bpf_core_field_exists(cgrp_new->ancestors)) { + return BPF_CORE_READ(cgrp_new, ancestors[level], kn, id); + } else { + /* recast pointer to capture old type for compiler */ + struct cgroup___old *cgrp_old = (void *)cgrp; + + return BPF_CORE_READ(cgrp_old, ancestor_ids[level]); + } +} + +static inline int get_cgroup_v1_idx(__u32 *cgrps, int size) +{ + struct task_struct *p = (void *)bpf_get_current_task(); + struct cgroup *cgrp; + register int i = 0; + __u32 *elem; + int level; + int cnt; + + if (perf_subsys_id == -1) { +#if __has_builtin(__builtin_preserve_enum_value) + perf_subsys_id = bpf_core_enum_value(enum cgroup_subsys_id, + perf_event_cgrp_id); +#else + perf_subsys_id = perf_event_cgrp_id; +#endif + } + cgrp = BPF_CORE_READ(p, cgroups, subsys[perf_subsys_id], cgroup); + level = BPF_CORE_READ(cgrp, level); + + for (cnt = 0; i < MAX_LEVELS; i++) { + __u64 cgrp_id; + + if (i > level) + break; + + // convert cgroup-id to a map index + cgrp_id = get_cgroup_v1_ancestor_id(cgrp, i); + elem = bpf_map_lookup_elem(&cgrp_idx, &cgrp_id); + if (!elem) + continue; + + cgrps[cnt++] = *elem; + if (cnt == size) + break; + } + + return cnt; +} + +static inline int get_cgroup_v2_idx(__u32 *cgrps, int size) +{ + register int i = 0; + __u32 *elem; + int cnt; + + for (cnt = 0; i < MAX_LEVELS; i++) { + __u64 cgrp_id = bpf_get_current_ancestor_cgroup_id(i); + + if (cgrp_id == 0) + break; + + // convert cgroup-id to a map index + elem = bpf_map_lookup_elem(&cgrp_idx, &cgrp_id); + if (!elem) + continue; + + cgrps[cnt++] = *elem; + if (cnt == size) + break; + } + + return cnt; +} + +static int bperf_cgroup_count(void) +{ + register __u32 idx = 0; // to have it in a register to pass BPF verifier + register int c = 0; + struct bpf_perf_event_value val, delta, *prev_val, *cgrp_val; + __u32 cpu = bpf_get_smp_processor_id(); + __u32 cgrp_idx[MAX_LEVELS]; + int cgrp_cnt; + __u32 key, cgrp; + long err; + + if (use_cgroup_v2) + cgrp_cnt = get_cgroup_v2_idx(cgrp_idx, MAX_LEVELS); + else + cgrp_cnt = get_cgroup_v1_idx(cgrp_idx, MAX_LEVELS); + + for ( ; idx < MAX_EVENTS; idx++) { + if (idx == num_events) + break; + + // XXX: do not pass idx directly (for verifier) + key = idx; + // this is per-cpu array for diff + prev_val = bpf_map_lookup_elem(&prev_readings, &key); + if (!prev_val) { + val.counter = val.enabled = val.running = 0; + bpf_map_update_elem(&prev_readings, &key, &val, BPF_ANY); + + prev_val = bpf_map_lookup_elem(&prev_readings, &key); + if (!prev_val) + continue; + } + + // read from global perf_event array + key = idx * num_cpus + cpu; + err = bpf_perf_event_read_value(&events, key, &val, sizeof(val)); + if (err) + continue; + + if (enabled) { + delta.counter = val.counter - prev_val->counter; + delta.enabled = val.enabled - prev_val->enabled; + delta.running = val.running - prev_val->running; + + for (c = 0; c < MAX_LEVELS; c++) { + if (c == cgrp_cnt) + break; + + cgrp = cgrp_idx[c]; + + // aggregate the result by cgroup + key = cgrp * num_events + idx; + cgrp_val = bpf_map_lookup_elem(&cgrp_readings, &key); + if (cgrp_val) { + cgrp_val->counter += delta.counter; + cgrp_val->enabled += delta.enabled; + cgrp_val->running += delta.running; + } else { + bpf_map_update_elem(&cgrp_readings, &key, + &delta, BPF_ANY); + } + } + } + + *prev_val = val; + } + return 0; +} + +// This will be attached to cgroup-switches event for each cpu +SEC("perf_event") +int BPF_PROG(on_cgrp_switch) +{ + return bperf_cgroup_count(); +} + +SEC("raw_tp/sched_switch") +int BPF_PROG(trigger_read) +{ + return bperf_cgroup_count(); +} + +char LICENSE[] SEC("license") = "Dual BSD/GPL"; |