tools/perf/util/bpf_counter_cgroup.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /* Copyright (c) 2021 Facebook */
   4 /* Copyright (c) 2021 Google */
   5
   6 #include <assert.h>
   7 #include <limits.h>
   8 #include <unistd.h>
   9 #include <sys/file.h>
  10 #include <sys/time.h>
  11 #include <sys/resource.h>
  12 #include <linux/err.h>
  13 #include <linux/zalloc.h>
  14 #include <linux/perf_event.h>
  15 #include <api/fs/fs.h>
  16 #include <perf/bpf_perf.h>
  17
  18 #include "affinity.h"
  19 #include "bpf_counter.h"
  20 #include "cgroup.h"
  21 #include "counts.h"
  22 #include "debug.h"
  23 #include "evsel.h"
  24 #include "evlist.h"
  25 #include "target.h"
  26 #include "cpumap.h"
  27 #include "thread_map.h"
  28
  29 #include "bpf_skel/bperf_cgroup.skel.h"
  30
  31 static struct perf_event_attr cgrp_switch_attr = {
  32         .type = PERF_TYPE_SOFTWARE,
  33         .config = PERF_COUNT_SW_CGROUP_SWITCHES,
  34         .size = sizeof(cgrp_switch_attr),
  35         .sample_period = 1,
  36         .disabled = 1,
  37 };
  38
  39 static struct evsel *cgrp_switch;
  40 static struct bperf_cgroup_bpf *skel;
  41
  42 #define FD(evt, cpu) (*(int *)xyarray__entry(evt->core.fd, cpu, 0))
  43
  44 static int bperf_load_program(struct evlist *evlist)
  45 {
  46         struct bpf_link *link;
  47         struct evsel *evsel;
  48         struct cgroup *cgrp, *leader_cgrp;
  49         int i, j;
  50         struct perf_cpu cpu;
  51         int total_cpus = cpu__max_cpu().cpu;
  52         int map_size, map_fd;
  53         int prog_fd, err;
  54
  55         skel = bperf_cgroup_bpf__open();
  56         if (!skel) {
  57                 pr_err("Failed to open cgroup skeleton\n");
  58                 return -1;
  59         }
  60
  61         skel->rodata->num_cpus = total_cpus;
  62         skel->rodata->num_events = evlist->core.nr_entries / nr_cgroups;
  63
  64         if (cgroup_is_v2("perf_event") > 0)
  65                 skel->rodata->use_cgroup_v2 = 1;
  66
  67         BUG_ON(evlist->core.nr_entries % nr_cgroups != 0);
  68
  69         /* we need one copy of events per cpu for reading */
  70         map_size = total_cpus * evlist->core.nr_entries / nr_cgroups;
  71         bpf_map__set_max_entries(skel->maps.events, map_size);
  72         bpf_map__set_max_entries(skel->maps.cgrp_idx, nr_cgroups);
  73         /* previous result is saved in a per-cpu array */
  74         map_size = evlist->core.nr_entries / nr_cgroups;
  75         bpf_map__set_max_entries(skel->maps.prev_readings, map_size);
  76         /* cgroup result needs all events (per-cpu) */
  77         map_size = evlist->core.nr_entries;
  78         bpf_map__set_max_entries(skel->maps.cgrp_readings, map_size);
  79
  80         set_max_rlimit();
  81
  82         err = bperf_cgroup_bpf__load(skel);
  83         if (err) {
  84                 pr_err("Failed to load cgroup skeleton\n");
  85                 goto out;
  86         }
  87
  88         err = -1;
  89
  90         cgrp_switch = evsel__new(&cgrp_switch_attr);
  91         if (evsel__open_per_cpu(cgrp_switch, evlist->core.all_cpus, -1) < 0) {
  92                 pr_err("Failed to open cgroup switches event\n");
  93                 goto out;
  94         }
  95
  96         perf_cpu_map__for_each_cpu(cpu, i, evlist->core.all_cpus) {
  97                 link = bpf_program__attach_perf_event(skel->progs.on_cgrp_switch,
  98                                                       FD(cgrp_switch, i));
  99                 if (IS_ERR(link)) {
 100                         pr_err("Failed to attach cgroup program\n");
 101                         err = PTR_ERR(link);
 102                         goto out;
 103                 }
 104         }
 105
 106         /*
 107          * Update cgrp_idx map from cgroup-id to event index.
 108          */
 109         cgrp = NULL;
 110         i = 0;
 111
 112         evlist__for_each_entry(evlist, evsel) {
 113                 if (cgrp == NULL || evsel->cgrp == leader_cgrp) {
 114                         leader_cgrp = evsel->cgrp;
 115                         evsel->cgrp = NULL;
 116
 117                         /* open single copy of the events w/o cgroup */
 118                         err = evsel__open_per_cpu(evsel, evsel->core.cpus, -1);
 119                         if (err == 0)
 120                                 evsel->supported = true;
 121
 122                         map_fd = bpf_map__fd(skel->maps.events);
 123                         perf_cpu_map__for_each_cpu(cpu, j, evsel->core.cpus) {
 124                                 int fd = FD(evsel, j);
 125                                 __u32 idx = evsel->core.idx * total_cpus + cpu.cpu;
 126
 127                                 bpf_map_update_elem(map_fd, &idx, &fd, BPF_ANY);
 128                         }
 129
 130                         evsel->cgrp = leader_cgrp;
 131                 }
 132
 133                 if (evsel->cgrp == cgrp)
 134                         continue;
 135
 136                 cgrp = evsel->cgrp;
 137
 138                 if (read_cgroup_id(cgrp) < 0) {
 139                         pr_debug("Failed to get cgroup id for %s\n", cgrp->name);
 140                         cgrp->id = 0;
 141                 }
 142
 143                 map_fd = bpf_map__fd(skel->maps.cgrp_idx);
 144                 err = bpf_map_update_elem(map_fd, &cgrp->id, &i, BPF_ANY);
 145                 if (err < 0) {
 146                         pr_err("Failed to update cgroup index map\n");
 147                         goto out;
 148                 }
 149
 150                 i++;
 151         }
 152
 153         /*
 154          * bperf uses BPF_PROG_TEST_RUN to get accurate reading. Check
 155          * whether the kernel support it
 156          */
 157         prog_fd = bpf_program__fd(skel->progs.trigger_read);
 158         err = bperf_trigger_reading(prog_fd, 0);
 159         if (err) {
 160                 pr_warning("The kernel does not support test_run for raw_tp BPF programs.\n"
 161                            "Therefore, --for-each-cgroup might show inaccurate readings\n");
 162                 err = 0;
 163         }
 164
 165 out:
 166         return err;
 167 }
 168
 169 static int bperf_cgrp__load(struct evsel *evsel,
 170                             struct target *target __maybe_unused)
 171 {
 172         static bool bperf_loaded = false;
 173
 174         evsel->bperf_leader_prog_fd = -1;
 175         evsel->bperf_leader_link_fd = -1;
 176
 177         if (!bperf_loaded && bperf_load_program(evsel->evlist))
 178                 return -1;
 179
 180         bperf_loaded = true;
 181         /* just to bypass bpf_counter_skip() */
 182         evsel->follower_skel = (struct bperf_follower_bpf *)skel;
 183
 184         return 0;
 185 }
 186
 187 static int bperf_cgrp__install_pe(struct evsel *evsel __maybe_unused,
 188                                   int cpu __maybe_unused, int fd __maybe_unused)
 189 {
 190         /* nothing to do */
 191         return 0;
 192 }
 193
 194 /*
 195  * trigger the leader prog on each cpu, so the cgrp_reading map could get
 196  * the latest results.
 197  */
 198 static int bperf_cgrp__sync_counters(struct evlist *evlist)
 199 {
 200         struct perf_cpu cpu;
 201         int idx;
 202         int prog_fd = bpf_program__fd(skel->progs.trigger_read);
 203
 204         perf_cpu_map__for_each_cpu(cpu, idx, evlist->core.all_cpus)
 205                 bperf_trigger_reading(prog_fd, cpu.cpu);
 206
 207         return 0;
 208 }
 209
 210 static int bperf_cgrp__enable(struct evsel *evsel)
 211 {
 212         if (evsel->core.idx)
 213                 return 0;
 214
 215         bperf_cgrp__sync_counters(evsel->evlist);
 216
 217         skel->bss->enabled = 1;
 218         return 0;
 219 }
 220
 221 static int bperf_cgrp__disable(struct evsel *evsel)
 222 {
 223         if (evsel->core.idx)
 224                 return 0;
 225
 226         bperf_cgrp__sync_counters(evsel->evlist);
 227
 228         skel->bss->enabled = 0;
 229         return 0;
 230 }
 231
 232 static int bperf_cgrp__read(struct evsel *evsel)
 233 {
 234         struct evlist *evlist = evsel->evlist;
 235         int total_cpus = cpu__max_cpu().cpu;
 236         struct perf_counts_values *counts;
 237         struct bpf_perf_event_value *values;
 238         int reading_map_fd, err = 0;
 239
 240         if (evsel->core.idx)
 241                 return 0;
 242
 243         bperf_cgrp__sync_counters(evsel->evlist);
 244
 245         values = calloc(total_cpus, sizeof(*values));
 246         if (values == NULL)
 247                 return -ENOMEM;
 248
 249         reading_map_fd = bpf_map__fd(skel->maps.cgrp_readings);
 250
 251         evlist__for_each_entry(evlist, evsel) {
 252                 __u32 idx = evsel->core.idx;
 253                 int i;
 254                 struct perf_cpu cpu;
 255
 256                 err = bpf_map_lookup_elem(reading_map_fd, &idx, values);
 257                 if (err) {
 258                         pr_err("bpf map lookup failed: idx=%u, event=%s, cgrp=%s\n",
 259                                idx, evsel__name(evsel), evsel->cgrp->name);
 260                         goto out;
 261                 }
 262
 263                 perf_cpu_map__for_each_cpu(cpu, i, evsel->core.cpus) {
 264                         counts = perf_counts(evsel->counts, i, 0);
 265                         counts->val = values[cpu.cpu].counter;
 266                         counts->ena = values[cpu.cpu].enabled;
 267                         counts->run = values[cpu.cpu].running;
 268                 }
 269         }
 270
 271 out:
 272         free(values);
 273         return err;
 274 }
 275
 276 static int bperf_cgrp__destroy(struct evsel *evsel)
 277 {
 278         if (evsel->core.idx)
 279                 return 0;
 280
 281         bperf_cgroup_bpf__destroy(skel);
 282         evsel__delete(cgrp_switch);  // it'll destroy on_switch progs too
 283
 284         return 0;
 285 }
 286
 287 struct bpf_counter_ops bperf_cgrp_ops = {
 288         .load       = bperf_cgrp__load,
 289         .enable     = bperf_cgrp__enable,
 290         .disable    = bperf_cgrp__disable,
 291         .read       = bperf_cgrp__read,
 292         .install_pe = bperf_cgrp__install_pe,
 293         .destroy    = bperf_cgrp__destroy,
 294 };