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   1 /*
   2  * builtin-stat.c
   3  *
   4  * Builtin stat command: Give a precise performance counters summary
   5  * overview about any workload, CPU or specific PID.
   6  *
   7  * Sample output:
   8
   9    $ perf stat ~/hackbench 10
  10    Time: 0.104
  11
  12     Performance counter stats for '/home/mingo/hackbench':
  13
  14        1255.538611  task clock ticks     #      10.143 CPU utilization factor
  15              54011  context switches     #       0.043 M/sec
  16                385  CPU migrations       #       0.000 M/sec
  17              17755  pagefaults           #       0.014 M/sec
  18         3808323185  CPU cycles           #    3033.219 M/sec
  19         1575111190  instructions         #    1254.530 M/sec
  20           17367895  cache references     #      13.833 M/sec
  21            7674421  cache misses         #       6.112 M/sec
  22
  23     Wall-clock time elapsed:   123.786620 msecs
  24
  25  *
  26  * Copyright (C) 2008, Red Hat Inc, Ingo Molnar <mingo@redhat.com>
  27  *
  28  * Improvements and fixes by:
  29  *
  30  *   Arjan van de Ven <arjan@linux.intel.com>
  31  *   Yanmin Zhang <yanmin.zhang@intel.com>
  32  *   Wu Fengguang <fengguang.wu@intel.com>
  33  *   Mike Galbraith <efault@gmx.de>
  34  *   Paul Mackerras <paulus@samba.org>
  35  *   Jaswinder Singh Rajput <jaswinder@kernel.org>
  36  *
  37  * Released under the GPL v2. (and only v2, not any later version)
  38  */
  39
  40 #include "perf.h"
  41 #include "builtin.h"
  42 #include "util/util.h"
  43 #include "util/parse-options.h"
  44 #include "util/parse-events.h"
  45 #include "util/event.h"
  46 #include "util/debug.h"
  47
  48 #include <sys/prctl.h>
  49 #include <math.h>
  50
  51 static struct perf_counter_attr default_attrs[] = {
  52
  53   { .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_TASK_CLOCK      },
  54   { .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_CONTEXT_SWITCHES},
  55   { .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_CPU_MIGRATIONS  },
  56   { .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_PAGE_FAULTS     },
  57
  58   { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_CPU_CYCLES      },
  59   { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_INSTRUCTIONS    },
  60   { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_CACHE_REFERENCES},
  61   { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_CACHE_MISSES    },
  62
  63 };
  64
  65 static int                      system_wide                     =  0;
  66 static unsigned int             nr_cpus                         =  0;
  67 static int                      run_idx                         =  0;
  68
  69 static int                      run_count                       =  1;
  70 static int                      inherit                         =  1;
  71 static int                      scale                           =  1;
  72 static int                      target_pid                      = -1;
  73 static int                      null_run                        =  0;
  74
  75 static int                      fd[MAX_NR_CPUS][MAX_COUNTERS];
  76
  77 static int                      event_scaled[MAX_COUNTERS];
  78
  79 struct stats
  80 {
  81         double n, mean, M2;
  82 };
  83
  84 static void update_stats(struct stats *stats, u64 val)
  85 {
  86         double delta;
  87
  88         stats->n++;
  89         delta = val - stats->mean;
  90         stats->mean += delta / stats->n;
  91         stats->M2 += delta*(val - stats->mean);
  92 }
  93
  94 static double avg_stats(struct stats *stats)
  95 {
  96         return stats->mean;
  97 }
  98
  99 /*
 100  * http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance
 101  *
 102  *       (\Sum n_i^2) - ((\Sum n_i)^2)/n
 103  * s^2 = -------------------------------
 104  *                  n - 1
 105  *
 106  * http://en.wikipedia.org/wiki/Stddev
 107  *
 108  * The std dev of the mean is related to the std dev by:
 109  *
 110  *             s
 111  * s_mean = -------
 112  *          sqrt(n)
 113  *
 114  */
 115 static double stddev_stats(struct stats *stats)
 116 {
 117         double variance = stats->M2 / (stats->n - 1);
 118         double variance_mean = variance / stats->n;
 119
 120         return sqrt(variance_mean);
 121 }
 122
 123 struct stats                    event_res_stats[MAX_COUNTERS][3];
 124 struct stats                    runtime_nsecs_stats;
 125 struct stats                    walltime_nsecs_stats;
 126 struct stats                    runtime_cycles_stats;
 127
 128 #define MATCH_EVENT(t, c, counter)                      \
 129         (attrs[counter].type == PERF_TYPE_##t &&        \
 130          attrs[counter].config == PERF_COUNT_##c)
 131
 132 #define ERR_PERF_OPEN \
 133 "Error: counter %d, sys_perf_counter_open() syscall returned with %d (%s)\n"
 134
 135 static void create_perf_stat_counter(int counter, int pid)
 136 {
 137         struct perf_counter_attr *attr = attrs + counter;
 138
 139         if (scale)
 140                 attr->read_format = PERF_FORMAT_TOTAL_TIME_ENABLED |
 141                                     PERF_FORMAT_TOTAL_TIME_RUNNING;
 142
 143         if (system_wide) {
 144                 unsigned int cpu;
 145
 146                 for (cpu = 0; cpu < nr_cpus; cpu++) {
 147                         fd[cpu][counter] = sys_perf_counter_open(attr, -1, cpu, -1, 0);
 148                         if (fd[cpu][counter] < 0 && verbose)
 149                                 fprintf(stderr, ERR_PERF_OPEN, counter,
 150                                         fd[cpu][counter], strerror(errno));
 151                 }
 152         } else {
 153                 attr->inherit        = inherit;
 154                 attr->disabled       = 1;
 155                 attr->enable_on_exec = 1;
 156
 157                 fd[0][counter] = sys_perf_counter_open(attr, pid, -1, -1, 0);
 158                 if (fd[0][counter] < 0 && verbose)
 159                         fprintf(stderr, ERR_PERF_OPEN, counter,
 160                                 fd[0][counter], strerror(errno));
 161         }
 162 }
 163
 164 /*
 165  * Does the counter have nsecs as a unit?
 166  */
 167 static inline int nsec_counter(int counter)
 168 {
 169         if (MATCH_EVENT(SOFTWARE, SW_CPU_CLOCK, counter) ||
 170             MATCH_EVENT(SOFTWARE, SW_TASK_CLOCK, counter))
 171                 return 1;
 172
 173         return 0;
 174 }
 175
 176 /*
 177  * Read out the results of a single counter:
 178  */
 179 static void read_counter(int counter)
 180 {
 181         u64 count[3], single_count[3];
 182         unsigned int cpu;
 183         size_t res, nv;
 184         int scaled;
 185         int i;
 186
 187         count[0] = count[1] = count[2] = 0;
 188
 189         nv = scale ? 3 : 1;
 190         for (cpu = 0; cpu < nr_cpus; cpu++) {
 191                 if (fd[cpu][counter] < 0)
 192                         continue;
 193
 194                 res = read(fd[cpu][counter], single_count, nv * sizeof(u64));
 195                 assert(res == nv * sizeof(u64));
 196
 197                 close(fd[cpu][counter]);
 198                 fd[cpu][counter] = -1;
 199
 200                 count[0] += single_count[0];
 201                 if (scale) {
 202                         count[1] += single_count[1];
 203                         count[2] += single_count[2];
 204                 }
 205         }
 206
 207         scaled = 0;
 208         if (scale) {
 209                 if (count[2] == 0) {
 210                         event_scaled[counter] = -1;
 211                         count[0] = 0;
 212                         return;
 213                 }
 214
 215                 if (count[2] < count[1]) {
 216                         event_scaled[counter] = 1;
 217                         count[0] = (unsigned long long)
 218                                 ((double)count[0] * count[1] / count[2] + 0.5);
 219                 }
 220         }
 221
 222         for (i = 0; i < 3; i++)
 223                 update_stats(&event_res_stats[counter][i], count[i]);
 224
 225         if (verbose) {
 226                 fprintf(stderr, "%s: %Ld %Ld %Ld\n", event_name(counter),
 227                                 count[0], count[1], count[2]);
 228         }
 229
 230         /*
 231          * Save the full runtime - to allow normalization during printout:
 232          */
 233         if (MATCH_EVENT(SOFTWARE, SW_TASK_CLOCK, counter))
 234                 update_stats(&runtime_nsecs_stats, count[0]);
 235         if (MATCH_EVENT(HARDWARE, HW_CPU_CYCLES, counter))
 236                 update_stats(&runtime_cycles_stats, count[0]);
 237 }
 238
 239 static int run_perf_stat(int argc __used, const char **argv)
 240 {
 241         unsigned long long t0, t1;
 242         int status = 0;
 243         int counter;
 244         int pid;
 245         int child_ready_pipe[2], go_pipe[2];
 246         char buf;
 247
 248         if (!system_wide)
 249                 nr_cpus = 1;
 250
 251         if (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0) {
 252                 perror("failed to create pipes");
 253                 exit(1);
 254         }
 255
 256         if ((pid = fork()) < 0)
 257                 perror("failed to fork");
 258
 259         if (!pid) {
 260                 close(child_ready_pipe[0]);
 261                 close(go_pipe[1]);
 262                 fcntl(go_pipe[0], F_SETFD, FD_CLOEXEC);
 263
 264                 /*
 265                  * Do a dummy execvp to get the PLT entry resolved,
 266                  * so we avoid the resolver overhead on the real
 267                  * execvp call.
 268                  */
 269                 execvp("", (char **)argv);
 270
 271                 /*
 272                  * Tell the parent we're ready to go
 273                  */
 274                 close(child_ready_pipe[1]);
 275
 276                 /*
 277                  * Wait until the parent tells us to go.
 278                  */
 279                 if (read(go_pipe[0], &buf, 1) == -1)
 280                         perror("unable to read pipe");
 281
 282                 execvp(argv[0], (char **)argv);
 283
 284                 perror(argv[0]);
 285                 exit(-1);
 286         }
 287
 288         /*
 289          * Wait for the child to be ready to exec.
 290          */
 291         close(child_ready_pipe[1]);
 292         close(go_pipe[0]);
 293         if (read(child_ready_pipe[0], &buf, 1) == -1)
 294                 perror("unable to read pipe");
 295         close(child_ready_pipe[0]);
 296
 297         for (counter = 0; counter < nr_counters; counter++)
 298                 create_perf_stat_counter(counter, pid);
 299
 300         /*
 301          * Enable counters and exec the command:
 302          */
 303         t0 = rdclock();
 304
 305         close(go_pipe[1]);
 306         wait(&status);
 307
 308         t1 = rdclock();
 309
 310         update_stats(&walltime_nsecs_stats, t1 - t0);
 311
 312         for (counter = 0; counter < nr_counters; counter++)
 313                 read_counter(counter);
 314
 315         return WEXITSTATUS(status);
 316 }
 317
 318 static void print_noise(int counter, double avg)
 319 {
 320         if (run_count == 1)
 321                 return;
 322
 323         fprintf(stderr, "   ( +- %7.3f%% )",
 324                         100 * stddev_stats(&event_res_stats[counter][0]) / avg);
 325 }
 326
 327 static void nsec_printout(int counter, double avg)
 328 {
 329         double msecs = avg / 1e6;
 330
 331         fprintf(stderr, " %14.6f  %-24s", msecs, event_name(counter));
 332
 333         if (MATCH_EVENT(SOFTWARE, SW_TASK_CLOCK, counter)) {
 334                 fprintf(stderr, " # %10.3f CPUs ",
 335                                 avg / avg_stats(&walltime_nsecs_stats));
 336         }
 337 }
 338
 339 static void abs_printout(int counter, double avg)
 340 {
 341         fprintf(stderr, " %14.0f  %-24s", avg, event_name(counter));
 342
 343         if (MATCH_EVENT(HARDWARE, HW_INSTRUCTIONS, counter)) {
 344                 fprintf(stderr, " # %10.3f IPC  ",
 345                                 avg / avg_stats(&runtime_cycles_stats));
 346         } else {
 347                 fprintf(stderr, " # %10.3f M/sec",
 348                                 1000.0 * avg / avg_stats(&runtime_nsecs_stats));
 349         }
 350 }
 351
 352 /*
 353  * Print out the results of a single counter:
 354  */
 355 static void print_counter(int counter)
 356 {
 357         double avg = avg_stats(&event_res_stats[counter][0]);
 358         int scaled = event_scaled[counter];
 359
 360         if (scaled == -1) {
 361                 fprintf(stderr, " %14s  %-24s\n",
 362                         "<not counted>", event_name(counter));
 363                 return;
 364         }
 365
 366         if (nsec_counter(counter))
 367                 nsec_printout(counter, avg);
 368         else
 369                 abs_printout(counter, avg);
 370
 371         print_noise(counter, avg);
 372
 373         if (scaled) {
 374                 double avg_enabled, avg_running;
 375
 376                 avg_enabled = avg_stats(&event_res_stats[counter][1]);
 377                 avg_running = avg_stats(&event_res_stats[counter][2]);
 378
 379                 fprintf(stderr, "  (scaled from %.2f%%)",
 380                                 100 * avg_running / avg_enabled);
 381         }
 382
 383         fprintf(stderr, "\n");
 384 }
 385
 386 static void print_stat(int argc, const char **argv)
 387 {
 388         int i, counter;
 389
 390         fflush(stdout);
 391
 392         fprintf(stderr, "\n");
 393         fprintf(stderr, " Performance counter stats for \'%s", argv[0]);
 394
 395         for (i = 1; i < argc; i++)
 396                 fprintf(stderr, " %s", argv[i]);
 397
 398         fprintf(stderr, "\'");
 399         if (run_count > 1)
 400                 fprintf(stderr, " (%d runs)", run_count);
 401         fprintf(stderr, ":\n\n");
 402
 403         for (counter = 0; counter < nr_counters; counter++)
 404                 print_counter(counter);
 405
 406         fprintf(stderr, "\n");
 407         fprintf(stderr, " %14.9f  seconds time elapsed",
 408                         avg_stats(&walltime_nsecs_stats)/1e9);
 409         if (run_count > 1) {
 410                 fprintf(stderr, "   ( +- %7.3f%% )",
 411                                 100*stddev_stats(&walltime_nsecs_stats) /
 412                                 avg_stats(&walltime_nsecs_stats));
 413         }
 414         fprintf(stderr, "\n\n");
 415 }
 416
 417 static volatile int signr = -1;
 418
 419 static void skip_signal(int signo)
 420 {
 421         signr = signo;
 422 }
 423
 424 static void sig_atexit(void)
 425 {
 426         if (signr == -1)
 427                 return;
 428
 429         signal(signr, SIG_DFL);
 430         kill(getpid(), signr);
 431 }
 432
 433 static const char * const stat_usage[] = {
 434         "perf stat [<options>] <command>",
 435         NULL
 436 };
 437
 438 static const struct option options[] = {
 439         OPT_CALLBACK('e', "event", NULL, "event",
 440                      "event selector. use 'perf list' to list available events",
 441                      parse_events),
 442         OPT_BOOLEAN('i', "inherit", &inherit,
 443                     "child tasks inherit counters"),
 444         OPT_INTEGER('p', "pid", &target_pid,
 445                     "stat events on existing pid"),
 446         OPT_BOOLEAN('a', "all-cpus", &system_wide,
 447                     "system-wide collection from all CPUs"),
 448         OPT_BOOLEAN('c', "scale", &scale,
 449                     "scale/normalize counters"),
 450         OPT_BOOLEAN('v', "verbose", &verbose,
 451                     "be more verbose (show counter open errors, etc)"),
 452         OPT_INTEGER('r', "repeat", &run_count,
 453                     "repeat command and print average + stddev (max: 100)"),
 454         OPT_BOOLEAN('n', "null", &null_run,
 455                     "null run - dont start any counters"),
 456         OPT_END()
 457 };
 458
 459 int cmd_stat(int argc, const char **argv, const char *prefix __used)
 460 {
 461         int status;
 462
 463         argc = parse_options(argc, argv, options, stat_usage,
 464                 PARSE_OPT_STOP_AT_NON_OPTION);
 465         if (!argc)
 466                 usage_with_options(stat_usage, options);
 467         if (run_count <= 0)
 468                 usage_with_options(stat_usage, options);
 469
 470         /* Set attrs and nr_counters if no event is selected and !null_run */
 471         if (!null_run && !nr_counters) {
 472                 memcpy(attrs, default_attrs, sizeof(default_attrs));
 473                 nr_counters = ARRAY_SIZE(default_attrs);
 474         }
 475
 476         nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 477         assert(nr_cpus <= MAX_NR_CPUS);
 478         assert((int)nr_cpus >= 0);
 479
 480         /*
 481          * We dont want to block the signals - that would cause
 482          * child tasks to inherit that and Ctrl-C would not work.
 483          * What we want is for Ctrl-C to work in the exec()-ed
 484          * task, but being ignored by perf stat itself:
 485          */
 486         atexit(sig_atexit);
 487         signal(SIGINT,  skip_signal);
 488         signal(SIGALRM, skip_signal);
 489         signal(SIGABRT, skip_signal);
 490
 491         status = 0;
 492         for (run_idx = 0; run_idx < run_count; run_idx++) {
 493                 if (run_count != 1 && verbose)
 494                         fprintf(stderr, "[ perf stat: executing run #%d ... ]\n", run_idx + 1);
 495                 status = run_perf_stat(argc, argv);
 496         }
 497
 498         print_stat(argc, argv);
 499
 500         return status;
 501 }