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![Namhyung Kim](/assets/img/avatar_default.png)
When --for-each-cgroup option is used, it fails when any of events is
not supported and exits immediately. This is not how 'perf stat'
handles unsupported events.
Let's ignore the failure and proceed with others so that the output is
similar to when BPF counters are not used:
Before:
$ sudo ./perf stat -a --bpf-counters -e L1-icache-loads,L1-dcache-loads --for-each-cgroup system.slice,user.slice sleep 1
Failed to open first cgroup events
$
After it shows output similat to when --bpf-counters isn't specified:
$ sudo ./perf stat -a --bpf-counters -e L1-icache-loads,L1-dcache-loads --for-each-cgroup system.slice,user.slice sleep 1
Performance counter stats for 'system wide':
<not supported> L1-icache-loads system.slice
29,892,418 L1-dcache-loads system.slice
<not supported> L1-icache-loads user.slice
52,497,220 L1-dcache-loads user.slice
$
Fixes: 944138f048
("perf stat: Enable BPF counter with --for-each-cgroup")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/r/20230104064402.1551516-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
295 lines
6.8 KiB
C
295 lines
6.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2021 Facebook */
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/* Copyright (c) 2021 Google */
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#include <assert.h>
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#include <limits.h>
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#include <unistd.h>
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#include <sys/file.h>
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#include <sys/time.h>
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#include <sys/resource.h>
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#include <linux/err.h>
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#include <linux/zalloc.h>
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#include <linux/perf_event.h>
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#include <api/fs/fs.h>
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#include <perf/bpf_perf.h>
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#include "affinity.h"
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#include "bpf_counter.h"
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#include "cgroup.h"
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#include "counts.h"
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#include "debug.h"
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#include "evsel.h"
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#include "evlist.h"
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#include "target.h"
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#include "cpumap.h"
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#include "thread_map.h"
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#include "bpf_skel/bperf_cgroup.skel.h"
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static struct perf_event_attr cgrp_switch_attr = {
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.type = PERF_TYPE_SOFTWARE,
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.config = PERF_COUNT_SW_CGROUP_SWITCHES,
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.size = sizeof(cgrp_switch_attr),
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.sample_period = 1,
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.disabled = 1,
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};
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static struct evsel *cgrp_switch;
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static struct bperf_cgroup_bpf *skel;
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#define FD(evt, cpu) (*(int *)xyarray__entry(evt->core.fd, cpu, 0))
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static int bperf_load_program(struct evlist *evlist)
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{
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struct bpf_link *link;
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struct evsel *evsel;
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struct cgroup *cgrp, *leader_cgrp;
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int i, j;
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struct perf_cpu cpu;
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int total_cpus = cpu__max_cpu().cpu;
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int map_size, map_fd;
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int prog_fd, err;
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skel = bperf_cgroup_bpf__open();
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if (!skel) {
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pr_err("Failed to open cgroup skeleton\n");
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return -1;
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}
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skel->rodata->num_cpus = total_cpus;
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skel->rodata->num_events = evlist->core.nr_entries / nr_cgroups;
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BUG_ON(evlist->core.nr_entries % nr_cgroups != 0);
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/* we need one copy of events per cpu for reading */
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map_size = total_cpus * evlist->core.nr_entries / nr_cgroups;
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bpf_map__set_max_entries(skel->maps.events, map_size);
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bpf_map__set_max_entries(skel->maps.cgrp_idx, nr_cgroups);
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/* previous result is saved in a per-cpu array */
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map_size = evlist->core.nr_entries / nr_cgroups;
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bpf_map__set_max_entries(skel->maps.prev_readings, map_size);
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/* cgroup result needs all events (per-cpu) */
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map_size = evlist->core.nr_entries;
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bpf_map__set_max_entries(skel->maps.cgrp_readings, map_size);
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set_max_rlimit();
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err = bperf_cgroup_bpf__load(skel);
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if (err) {
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pr_err("Failed to load cgroup skeleton\n");
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goto out;
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}
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if (cgroup_is_v2("perf_event") > 0)
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skel->bss->use_cgroup_v2 = 1;
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err = -1;
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cgrp_switch = evsel__new(&cgrp_switch_attr);
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if (evsel__open_per_cpu(cgrp_switch, evlist->core.all_cpus, -1) < 0) {
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pr_err("Failed to open cgroup switches event\n");
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goto out;
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}
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perf_cpu_map__for_each_cpu(cpu, i, evlist->core.all_cpus) {
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link = bpf_program__attach_perf_event(skel->progs.on_cgrp_switch,
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FD(cgrp_switch, i));
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if (IS_ERR(link)) {
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pr_err("Failed to attach cgroup program\n");
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err = PTR_ERR(link);
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goto out;
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}
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}
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/*
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* Update cgrp_idx map from cgroup-id to event index.
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*/
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cgrp = NULL;
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i = 0;
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evlist__for_each_entry(evlist, evsel) {
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if (cgrp == NULL || evsel->cgrp == leader_cgrp) {
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leader_cgrp = evsel->cgrp;
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evsel->cgrp = NULL;
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/* open single copy of the events w/o cgroup */
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err = evsel__open_per_cpu(evsel, evsel->core.cpus, -1);
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if (err == 0)
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evsel->supported = true;
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map_fd = bpf_map__fd(skel->maps.events);
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perf_cpu_map__for_each_cpu(cpu, j, evsel->core.cpus) {
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int fd = FD(evsel, j);
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__u32 idx = evsel->core.idx * total_cpus + cpu.cpu;
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bpf_map_update_elem(map_fd, &idx, &fd, BPF_ANY);
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}
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evsel->cgrp = leader_cgrp;
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}
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if (evsel->cgrp == cgrp)
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continue;
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cgrp = evsel->cgrp;
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if (read_cgroup_id(cgrp) < 0) {
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pr_err("Failed to get cgroup id\n");
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err = -1;
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goto out;
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}
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map_fd = bpf_map__fd(skel->maps.cgrp_idx);
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err = bpf_map_update_elem(map_fd, &cgrp->id, &i, BPF_ANY);
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if (err < 0) {
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pr_err("Failed to update cgroup index map\n");
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goto out;
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}
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i++;
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}
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/*
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* bperf uses BPF_PROG_TEST_RUN to get accurate reading. Check
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* whether the kernel support it
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*/
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prog_fd = bpf_program__fd(skel->progs.trigger_read);
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err = bperf_trigger_reading(prog_fd, 0);
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if (err) {
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pr_warning("The kernel does not support test_run for raw_tp BPF programs.\n"
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"Therefore, --for-each-cgroup might show inaccurate readings\n");
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err = 0;
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}
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out:
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return err;
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}
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static int bperf_cgrp__load(struct evsel *evsel,
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struct target *target __maybe_unused)
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{
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static bool bperf_loaded = false;
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evsel->bperf_leader_prog_fd = -1;
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evsel->bperf_leader_link_fd = -1;
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if (!bperf_loaded && bperf_load_program(evsel->evlist))
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return -1;
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bperf_loaded = true;
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/* just to bypass bpf_counter_skip() */
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evsel->follower_skel = (struct bperf_follower_bpf *)skel;
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return 0;
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}
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static int bperf_cgrp__install_pe(struct evsel *evsel __maybe_unused,
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int cpu __maybe_unused, int fd __maybe_unused)
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{
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/* nothing to do */
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return 0;
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}
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/*
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* trigger the leader prog on each cpu, so the cgrp_reading map could get
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* the latest results.
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*/
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static int bperf_cgrp__sync_counters(struct evlist *evlist)
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{
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struct perf_cpu cpu;
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int idx;
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int prog_fd = bpf_program__fd(skel->progs.trigger_read);
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perf_cpu_map__for_each_cpu(cpu, idx, evlist->core.all_cpus)
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bperf_trigger_reading(prog_fd, cpu.cpu);
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return 0;
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}
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static int bperf_cgrp__enable(struct evsel *evsel)
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{
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if (evsel->core.idx)
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return 0;
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bperf_cgrp__sync_counters(evsel->evlist);
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skel->bss->enabled = 1;
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return 0;
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}
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static int bperf_cgrp__disable(struct evsel *evsel)
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{
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if (evsel->core.idx)
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return 0;
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bperf_cgrp__sync_counters(evsel->evlist);
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skel->bss->enabled = 0;
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return 0;
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}
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static int bperf_cgrp__read(struct evsel *evsel)
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{
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struct evlist *evlist = evsel->evlist;
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int total_cpus = cpu__max_cpu().cpu;
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struct perf_counts_values *counts;
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struct bpf_perf_event_value *values;
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int reading_map_fd, err = 0;
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if (evsel->core.idx)
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return 0;
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bperf_cgrp__sync_counters(evsel->evlist);
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values = calloc(total_cpus, sizeof(*values));
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if (values == NULL)
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return -ENOMEM;
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reading_map_fd = bpf_map__fd(skel->maps.cgrp_readings);
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evlist__for_each_entry(evlist, evsel) {
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__u32 idx = evsel->core.idx;
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int i;
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struct perf_cpu cpu;
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err = bpf_map_lookup_elem(reading_map_fd, &idx, values);
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if (err) {
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pr_err("bpf map lookup failed: idx=%u, event=%s, cgrp=%s\n",
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idx, evsel__name(evsel), evsel->cgrp->name);
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goto out;
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}
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perf_cpu_map__for_each_cpu(cpu, i, evsel->core.cpus) {
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counts = perf_counts(evsel->counts, i, 0);
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counts->val = values[cpu.cpu].counter;
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counts->ena = values[cpu.cpu].enabled;
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counts->run = values[cpu.cpu].running;
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}
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}
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out:
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free(values);
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return err;
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}
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static int bperf_cgrp__destroy(struct evsel *evsel)
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{
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if (evsel->core.idx)
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return 0;
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bperf_cgroup_bpf__destroy(skel);
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evsel__delete(cgrp_switch); // it'll destroy on_switch progs too
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return 0;
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}
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struct bpf_counter_ops bperf_cgrp_ops = {
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.load = bperf_cgrp__load,
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.enable = bperf_cgrp__enable,
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.disable = bperf_cgrp__disable,
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.read = bperf_cgrp__read,
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.install_pe = bperf_cgrp__install_pe,
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.destroy = bperf_cgrp__destroy,
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};
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