tools/perf/util/record.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "debug.h"
   3 #include "evlist.h"
   4 #include "evsel.h"
   5 #include "parse-events.h"
   6 #include <errno.h>
   7 #include <limits.h>
   8 #include <stdlib.h>
   9 #include <api/fs/fs.h>
  10 #include <subcmd/parse-options.h>
  11 #include <perf/cpumap.h>
  12 #include "cloexec.h"
  13 #include "util/perf_api_probe.h"
  14 #include "record.h"
  15 #include "../perf-sys.h"
  16
  17 /*
  18  * evsel__config_leader_sampling() uses special rules for leader sampling.
  19  * However, if the leader is an AUX area event, then assume the event to sample
  20  * is the next event.
  21  */
  22 static struct evsel *evsel__read_sampler(struct evsel *evsel, struct evlist *evlist)
  23 {
  24         struct evsel *leader = evsel->leader;
  25
  26         if (evsel__is_aux_event(leader)) {
  27                 evlist__for_each_entry(evlist, evsel) {
  28                         if (evsel->leader == leader && evsel != evsel->leader)
  29                                 return evsel;
  30                 }
  31         }
  32
  33         return leader;
  34 }
  35
  36 static void evsel__config_leader_sampling(struct evsel *evsel, struct evlist *evlist)
  37 {
  38         struct perf_event_attr *attr = &evsel->core.attr;
  39         struct evsel *leader = evsel->leader;
  40         struct evsel *read_sampler;
  41
  42         if (!leader->sample_read)
  43                 return;
  44
  45         read_sampler = evsel__read_sampler(evsel, evlist);
  46
  47         if (evsel == read_sampler)
  48                 return;
  49
  50         /*
  51          * Disable sampling for all group members other than the leader in
  52          * case the leader 'leads' the sampling, except when the leader is an
  53          * AUX area event, in which case the 2nd event in the group is the one
  54          * that 'leads' the sampling.
  55          */
  56         attr->freq           = 0;
  57         attr->sample_freq    = 0;
  58         attr->sample_period  = 0;
  59         attr->write_backward = 0;
  60
  61         /*
  62          * We don't get a sample for slave events, we make them when delivering
  63          * the group leader sample. Set the slave event to follow the master
  64          * sample_type to ease up reporting.
  65          * An AUX area event also has sample_type requirements, so also include
  66          * the sample type bits from the leader's sample_type to cover that
  67          * case.
  68          */
  69         attr->sample_type = read_sampler->core.attr.sample_type |
  70                             leader->core.attr.sample_type;
  71 }
  72
  73 void perf_evlist__config(struct evlist *evlist, struct record_opts *opts,
  74                          struct callchain_param *callchain)
  75 {
  76         struct evsel *evsel;
  77         bool use_sample_identifier = false;
  78         bool use_comm_exec;
  79         bool sample_id = opts->sample_id;
  80
  81         /*
  82          * Set the evsel leader links before we configure attributes,
  83          * since some might depend on this info.
  84          */
  85         if (opts->group)
  86                 perf_evlist__set_leader(evlist);
  87
  88         if (evlist->core.cpus->map[0] < 0)
  89                 opts->no_inherit = true;
  90
  91         use_comm_exec = perf_can_comm_exec();
  92
  93         evlist__for_each_entry(evlist, evsel) {
  94                 evsel__config(evsel, opts, callchain);
  95                 if (evsel->tracking && use_comm_exec)
  96                         evsel->core.attr.comm_exec = 1;
  97         }
  98
  99         /* Configure leader sampling here now that the sample type is known */
 100         evlist__for_each_entry(evlist, evsel)
 101                 evsel__config_leader_sampling(evsel, evlist);
 102
 103         if (opts->full_auxtrace) {
 104                 /*
 105                  * Need to be able to synthesize and parse selected events with
 106                  * arbitrary sample types, which requires always being able to
 107                  * match the id.
 108                  */
 109                 use_sample_identifier = perf_can_sample_identifier();
 110                 sample_id = true;
 111         } else if (evlist->core.nr_entries > 1) {
 112                 struct evsel *first = evlist__first(evlist);
 113
 114                 evlist__for_each_entry(evlist, evsel) {
 115                         if (evsel->core.attr.sample_type == first->core.attr.sample_type)
 116                                 continue;
 117                         use_sample_identifier = perf_can_sample_identifier();
 118                         break;
 119                 }
 120                 sample_id = true;
 121         }
 122
 123         if (sample_id) {
 124                 evlist__for_each_entry(evlist, evsel)
 125                         evsel__set_sample_id(evsel, use_sample_identifier);
 126         }
 127
 128         perf_evlist__set_id_pos(evlist);
 129 }
 130
 131 static int get_max_rate(unsigned int *rate)
 132 {
 133         return sysctl__read_int("kernel/perf_event_max_sample_rate", (int *)rate);
 134 }
 135
 136 static int record_opts__config_freq(struct record_opts *opts)
 137 {
 138         bool user_freq = opts->user_freq != UINT_MAX;
 139         unsigned int max_rate;
 140
 141         if (opts->user_interval != ULLONG_MAX)
 142                 opts->default_interval = opts->user_interval;
 143         if (user_freq)
 144                 opts->freq = opts->user_freq;
 145
 146         /*
 147          * User specified count overrides default frequency.
 148          */
 149         if (opts->default_interval)
 150                 opts->freq = 0;
 151         else if (opts->freq) {
 152                 opts->default_interval = opts->freq;
 153         } else {
 154                 pr_err("frequency and count are zero, aborting\n");
 155                 return -1;
 156         }
 157
 158         if (get_max_rate(&max_rate))
 159                 return 0;
 160
 161         /*
 162          * User specified frequency is over current maximum.
 163          */
 164         if (user_freq && (max_rate < opts->freq)) {
 165                 if (opts->strict_freq) {
 166                         pr_err("error: Maximum frequency rate (%'u Hz) exceeded.\n"
 167                                "       Please use -F freq option with a lower value or consider\n"
 168                                "       tweaking /proc/sys/kernel/perf_event_max_sample_rate.\n",
 169                                max_rate);
 170                         return -1;
 171                 } else {
 172                         pr_warning("warning: Maximum frequency rate (%'u Hz) exceeded, throttling from %'u Hz to %'u Hz.\n"
 173                                    "         The limit can be raised via /proc/sys/kernel/perf_event_max_sample_rate.\n"
 174                                    "         The kernel will lower it when perf's interrupts take too long.\n"
 175                                    "         Use --strict-freq to disable this throttling, refusing to record.\n",
 176                                    max_rate, opts->freq, max_rate);
 177
 178                         opts->freq = max_rate;
 179                 }
 180         }
 181
 182         /*
 183          * Default frequency is over current maximum.
 184          */
 185         if (max_rate < opts->freq) {
 186                 pr_warning("Lowering default frequency rate to %u.\n"
 187                            "Please consider tweaking "
 188                            "/proc/sys/kernel/perf_event_max_sample_rate.\n",
 189                            max_rate);
 190                 opts->freq = max_rate;
 191         }
 192
 193         return 0;
 194 }
 195
 196 int record_opts__config(struct record_opts *opts)
 197 {
 198         return record_opts__config_freq(opts);
 199 }
 200
 201 bool perf_evlist__can_select_event(struct evlist *evlist, const char *str)
 202 {
 203         struct evlist *temp_evlist;
 204         struct evsel *evsel;
 205         int err, fd, cpu;
 206         bool ret = false;
 207         pid_t pid = -1;
 208
 209         temp_evlist = evlist__new();
 210         if (!temp_evlist)
 211                 return false;
 212
 213         err = parse_events(temp_evlist, str, NULL);
 214         if (err)
 215                 goto out_delete;
 216
 217         evsel = evlist__last(temp_evlist);
 218
 219         if (!evlist || perf_cpu_map__empty(evlist->core.cpus)) {
 220                 struct perf_cpu_map *cpus = perf_cpu_map__new(NULL);
 221
 222                 cpu =  cpus ? cpus->map[0] : 0;
 223                 perf_cpu_map__put(cpus);
 224         } else {
 225                 cpu = evlist->core.cpus->map[0];
 226         }
 227
 228         while (1) {
 229                 fd = sys_perf_event_open(&evsel->core.attr, pid, cpu, -1,
 230                                          perf_event_open_cloexec_flag());
 231                 if (fd < 0) {
 232                         if (pid == -1 && errno == EACCES) {
 233                                 pid = 0;
 234                                 continue;
 235                         }
 236                         goto out_delete;
 237                 }
 238                 break;
 239         }
 240         close(fd);
 241         ret = true;
 242
 243 out_delete:
 244         evlist__delete(temp_evlist);
 245         return ret;
 246 }
 247
 248 int record__parse_freq(const struct option *opt, const char *str, int unset __maybe_unused)
 249 {
 250         unsigned int freq;
 251         struct record_opts *opts = opt->value;
 252
 253         if (!str)
 254                 return -EINVAL;
 255
 256         if (strcasecmp(str, "max") == 0) {
 257                 if (get_max_rate(&freq)) {
 258                         pr_err("couldn't read /proc/sys/kernel/perf_event_max_sample_rate\n");
 259                         return -1;
 260                 }
 261                 pr_info("info: Using a maximum frequency rate of %'d Hz\n", freq);
 262         } else {
 263                 freq = atoi(str);
 264         }
 265
 266         opts->user_freq = freq;
 267         return 0;
 268 }