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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:

9 $ perf stat ~/hackbench 10

10 Time: 0.104

12 Performance counter stats for '/home/mingo/hackbench':

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

23 Wall-clock time elapsed: 123.786620 msecs

25 *

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 */

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"

48 #include <sys/prctl.h>

49 #include <math.h>

51 static struct perf_event_attr default_attrs[] = {

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 },

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 { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS},

63 { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_BRANCH_MISSES },

65 };

67 static int system_wide = 0;

68 static unsigned int nr_cpus = 0;

69 static int run_idx = 0;

71 static int run_count = 1;

72 static int inherit = 1;

73 static int scale = 1;

74 static pid_t target_pid = -1;

75 static pid_t child_pid = -1;

76 static int null_run = 0;

78 static int fd[MAX_NR_CPUS][MAX_COUNTERS];

80 static int event_scaled[MAX_COUNTERS];

82 struct stats

83 {

84 double n, mean, M2;

85 };

87 static void update_stats(struct stats *stats, u64 val)

88 {

89 double delta;

91 stats->n++;

92 delta = val - stats->mean;

93 stats->mean += delta / stats->n;

94 stats->M2 += delta*(val - stats->mean);

95 }

97 static double avg_stats(struct stats *stats)

98 {

99 return stats->mean;

100 }

101

102 /*

103 * http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance

104 *

105 * (\Sum n_i^2) - ((\Sum n_i)^2)/n

106 * s^2 = -------------------------------

107 * n - 1

108 *

109 * http://en.wikipedia.org/wiki/Stddev

110 *

111 * The std dev of the mean is related to the std dev by:

112 *

113 * s

114 * s_mean = -------

115 * sqrt(n)

116 *

117 */

118 static double stddev_stats(struct stats *stats)

119 {

120 double variance = stats->M2 / (stats->n - 1);

121 double variance_mean = variance / stats->n;

122

123 return sqrt(variance_mean);

124 }

125

126 struct stats event_res_stats[MAX_COUNTERS][3];

127 struct stats runtime_nsecs_stats;

128 struct stats walltime_nsecs_stats;

129 struct stats runtime_cycles_stats;

130 struct stats runtime_branches_stats;

131

132 #define MATCH_EVENT(t, c, counter) \

133 (attrs[counter].type == PERF_TYPE_##t && \

134 attrs[counter].config == PERF_COUNT_##c)

135

136 #define ERR_PERF_OPEN \

137 "Error: counter %d, sys_perf_event_open() syscall returned with %d (%s)\n"

138

139 static void create_perf_stat_counter(int counter, int pid)

140 {

141 struct perf_event_attr *attr = attrs + counter;

142

143 if (scale)

144 attr->read_format = PERF_FORMAT_TOTAL_TIME_ENABLED |

145 PERF_FORMAT_TOTAL_TIME_RUNNING;

146

147 if (system_wide) {

148 unsigned int cpu;

149

150 for (cpu = 0; cpu < nr_cpus; cpu++) {

151 fd[cpu][counter] = sys_perf_event_open(attr, -1, cpu, -1, 0);

152 if (fd[cpu][counter] < 0 && verbose)

153 fprintf(stderr, ERR_PERF_OPEN, counter,

154 fd[cpu][counter], strerror(errno));

155 }

156 } else {

157 attr->inherit = inherit;

158 attr->disabled = 1;

159 attr->enable_on_exec = 1;

160

161 fd[0][counter] = sys_perf_event_open(attr, pid, -1, -1, 0);

162 if (fd[0][counter] < 0 && verbose)

163 fprintf(stderr, ERR_PERF_OPEN, counter,

164 fd[0][counter], strerror(errno));

165 }

166 }

167

168 /*

169 * Does the counter have nsecs as a unit?

170 */

171 static inline int nsec_counter(int counter)

172 {

173 if (MATCH_EVENT(SOFTWARE, SW_CPU_CLOCK, counter) ||

174 MATCH_EVENT(SOFTWARE, SW_TASK_CLOCK, counter))

175 return 1;

176

177 return 0;

178 }

179

180 /*

181 * Read out the results of a single counter:

182 */

183 static void read_counter(int counter)

184 {

185 u64 count[3], single_count[3];

186 unsigned int cpu;

187 size_t res, nv;

188 int scaled;

189 int i;

190

191 count[0] = count[1] = count[2] = 0;

192

193 nv = scale ? 3 : 1;

194 for (cpu = 0; cpu < nr_cpus; cpu++) {

195 if (fd[cpu][counter] < 0)

196 continue;

197

198 res = read(fd[cpu][counter], single_count, nv * sizeof(u64));

199 assert(res == nv * sizeof(u64));

200

201 close(fd[cpu][counter]);

202 fd[cpu][counter] = -1;

203

204 count[0] += single_count[0];

205 if (scale) {

206 count[1] += single_count[1];

207 count[2] += single_count[2];

208 }

209 }

210

211 scaled = 0;

212 if (scale) {

213 if (count[2] == 0) {

214 event_scaled[counter] = -1;

215 count[0] = 0;

216 return;

217 }

218

219 if (count[2] < count[1]) {

220 event_scaled[counter] = 1;

221 count[0] = (unsigned long long)

222 ((double)count[0] * count[1] / count[2] + 0.5);

223 }

224 }

225

226 for (i = 0; i < 3; i++)

227 update_stats(&event_res_stats[counter][i], count[i]);

228

229 if (verbose) {

230 fprintf(stderr, "%s: %Ld %Ld %Ld\n", event_name(counter),

231 count[0], count[1], count[2]);

232 }

233

234 /*

235 * Save the full runtime - to allow normalization during printout:

236 */

237 if (MATCH_EVENT(SOFTWARE, SW_TASK_CLOCK, counter))

238 update_stats(&runtime_nsecs_stats, count[0]);

239 if (MATCH_EVENT(HARDWARE, HW_CPU_CYCLES, counter))

240 update_stats(&runtime_cycles_stats, count[0]);

241 if (MATCH_EVENT(HARDWARE, HW_BRANCH_INSTRUCTIONS, counter))

242 update_stats(&runtime_branches_stats, count[0]);

243 }

244

245 static int run_perf_stat(int argc __used, const char **argv)

246 {

247 unsigned long long t0, t1;

248 int status = 0;

249 int counter;

250 int pid;

251 int child_ready_pipe[2], go_pipe[2];

252 char buf;

253

254 if (!system_wide)

255 nr_cpus = 1;

256

257 if (pipe(child_ready_pipe) < 0 || pipe(go_pipe) < 0) {

258 perror("failed to create pipes");

259 exit(1);

260 }

261

262 if ((pid = fork()) < 0)

263 perror("failed to fork");

264

265 if (!pid) {

266 close(child_ready_pipe[0]);

267 close(go_pipe[1]);

268 fcntl(go_pipe[0], F_SETFD, FD_CLOEXEC);

269

270 /*

271 * Do a dummy execvp to get the PLT entry resolved,

272 * so we avoid the resolver overhead on the real

273 * execvp call.

274 */

275 execvp("", (char **)argv);

276

277 /*

278 * Tell the parent we're ready to go

279 */

280 close(child_ready_pipe[1]);

281

282 /*

283 * Wait until the parent tells us to go.

284 */

285 if (read(go_pipe[0], &buf, 1) == -1)

286 perror("unable to read pipe");

287

288 execvp(argv[0], (char **)argv);

289

290 perror(argv[0]);

291 exit(-1);

292 }

293

294 child_pid = pid;

295

296 /*

297 * Wait for the child to be ready to exec.

298 */

299 close(child_ready_pipe[1]);

300 close(go_pipe[0]);

301 if (read(child_ready_pipe[0], &buf, 1) == -1)

302 perror("unable to read pipe");

303 close(child_ready_pipe[0]);

304

305 for (counter = 0; counter < nr_counters; counter++)

306 create_perf_stat_counter(counter, pid);

307

308 /*

309 * Enable counters and exec the command:

310 */

311 t0 = rdclock();

312

313 close(go_pipe[1]);

314 wait(&status);

315

316 t1 = rdclock();

317

318 update_stats(&walltime_nsecs_stats, t1 - t0);

319

320 for (counter = 0; counter < nr_counters; counter++)

321 read_counter(counter);

322

323 return WEXITSTATUS(status);

324 }

325

326 static void print_noise(int counter, double avg)

327 {

328 if (run_count == 1)

329 return;

330

331 fprintf(stderr, " ( +- %7.3f%% )",

332 100 * stddev_stats(&event_res_stats[counter][0]) / avg);

333 }

334

335 static void nsec_printout(int counter, double avg)

336 {

337 double msecs = avg / 1e6;

338

339 fprintf(stderr, " %14.6f %-24s", msecs, event_name(counter));

340

341 if (MATCH_EVENT(SOFTWARE, SW_TASK_CLOCK, counter)) {

342 fprintf(stderr, " # %10.3f CPUs ",

343 avg / avg_stats(&walltime_nsecs_stats));

344 }

345 }

346

347 static void abs_printout(int counter, double avg)

348 {

349 double total, ratio = 0.0;

350

351 fprintf(stderr, " %14.0f %-24s", avg, event_name(counter));

352

353 if (MATCH_EVENT(HARDWARE, HW_INSTRUCTIONS, counter)) {

354 total = avg_stats(&runtime_cycles_stats);

355

356 if (total)

357 ratio = avg / total;

358

359 fprintf(stderr, " # %10.3f IPC ", ratio);

360 } else if (MATCH_EVENT(HARDWARE, HW_BRANCH_MISSES, counter)) {

361 total = avg_stats(&runtime_branches_stats);

362

363 if (total)

364 ratio = avg * 100 / total;

365

366 fprintf(stderr, " # %10.3f %% ", ratio);

367

368 } else {

369 total = avg_stats(&runtime_nsecs_stats);

370

371 if (total)

372 ratio = 1000.0 * avg / total;

373

374 fprintf(stderr, " # %10.3f M/sec", ratio);

375 }

376 }

377

378 /*

379 * Print out the results of a single counter:

380 */

381 static void print_counter(int counter)

382 {

383 double avg = avg_stats(&event_res_stats[counter][0]);

384 int scaled = event_scaled[counter];

385

386 if (scaled == -1) {

387 fprintf(stderr, " %14s %-24s\n",

388 "<not counted>", event_name(counter));

389 return;

390 }

391

392 if (nsec_counter(counter))

393 nsec_printout(counter, avg);

394 else

395 abs_printout(counter, avg);

396

397 print_noise(counter, avg);

398

399 if (scaled) {

400 double avg_enabled, avg_running;

401

402 avg_enabled = avg_stats(&event_res_stats[counter][1]);

403 avg_running = avg_stats(&event_res_stats[counter][2]);

404

405 fprintf(stderr, " (scaled from %.2f%%)",

406 100 * avg_running / avg_enabled);

407 }

408

409 fprintf(stderr, "\n");

410 }

411

412 static void print_stat(int argc, const char **argv)

413 {

414 int i, counter;

415

416 fflush(stdout);

417

418 fprintf(stderr, "\n");

419 fprintf(stderr, " Performance counter stats for \'%s", argv[0]);

420

421 for (i = 1; i < argc; i++)

422 fprintf(stderr, " %s", argv[i]);

423

424 fprintf(stderr, "\'");

425 if (run_count > 1)

426 fprintf(stderr, " (%d runs)", run_count);

427 fprintf(stderr, ":\n\n");

428

429 for (counter = 0; counter < nr_counters; counter++)

430 print_counter(counter);

431

432 fprintf(stderr, "\n");

433 fprintf(stderr, " %14.9f seconds time elapsed",

434 avg_stats(&walltime_nsecs_stats)/1e9);

435 if (run_count > 1) {

436 fprintf(stderr, " ( +- %7.3f%% )",

437 100*stddev_stats(&walltime_nsecs_stats) /

438 avg_stats(&walltime_nsecs_stats));

439 }

440 fprintf(stderr, "\n\n");

441 }

442

443 static volatile int signr = -1;

444

445 static void skip_signal(int signo)

446 {

447 signr = signo;

448 }

449

450 static void sig_atexit(void)

451 {

452 if (child_pid != -1)

453 kill(child_pid, SIGTERM);

454

455 if (signr == -1)

456 return;

457

458 signal(signr, SIG_DFL);

459 kill(getpid(), signr);

460 }

461

462 static const char * const stat_usage[] = {

463 "perf stat [<options>] <command>",

464 NULL

465 };

466

467 static const struct option options[] = {

468 OPT_CALLBACK('e', "event", NULL, "event",

469 "event selector. use 'perf list' to list available events",

470 parse_events),

471 OPT_BOOLEAN('i', "inherit", &inherit,

472 "child tasks inherit counters"),

473 OPT_INTEGER('p', "pid", &target_pid,

474 "stat events on existing pid"),

475 OPT_BOOLEAN('a', "all-cpus", &system_wide,

476 "system-wide collection from all CPUs"),

477 OPT_BOOLEAN('c', "scale", &scale,

478 "scale/normalize counters"),

479 OPT_BOOLEAN('v', "verbose", &verbose,

480 "be more verbose (show counter open errors, etc)"),

481 OPT_INTEGER('r', "repeat", &run_count,

482 "repeat command and print average + stddev (max: 100)"),

483 OPT_BOOLEAN('n', "null", &null_run,

484 "null run - dont start any counters"),

485 OPT_END()

486 };

487

488 int cmd_stat(int argc, const char **argv, const char *prefix __used)

489 {

490 int status;

491

492 argc = parse_options(argc, argv, options, stat_usage,

493 PARSE_OPT_STOP_AT_NON_OPTION);

494 if (!argc)

495 usage_with_options(stat_usage, options);

496 if (run_count <= 0)

497 usage_with_options(stat_usage, options);

498

499 /* Set attrs and nr_counters if no event is selected and !null_run */

500 if (!null_run && !nr_counters) {

501 memcpy(attrs, default_attrs, sizeof(default_attrs));

502 nr_counters = ARRAY_SIZE(default_attrs);

503 }

504

505 nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);

506 assert(nr_cpus <= MAX_NR_CPUS);

507 assert((int)nr_cpus >= 0);

508

509 /*

510 * We dont want to block the signals - that would cause

511 * child tasks to inherit that and Ctrl-C would not work.

512 * What we want is for Ctrl-C to work in the exec()-ed

513 * task, but being ignored by perf stat itself:

514 */

515 atexit(sig_atexit);

516 signal(SIGINT, skip_signal);

517 signal(SIGALRM, skip_signal);

518 signal(SIGABRT, skip_signal);

519

520 status = 0;

521 for (run_idx = 0; run_idx < run_count; run_idx++) {

522 if (run_count != 1 && verbose)

523 fprintf(stderr, "[ perf stat: executing run #%d ... ]\n", run_idx + 1);

524 status = run_perf_stat(argc, argv);

525 }

526

527 print_stat(argc, argv);

528

529 return status;

530 }