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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 },

63 };

65 static int system_wide = 0;

66 static unsigned int nr_cpus = 0;

67 static int run_idx = 0;

69 static int run_count = 1;

70 static int inherit = 1;

71 static int scale = 1;

72 static pid_t target_pid = -1;

73 static pid_t child_pid = -1;

74 static int null_run = 0;

76 static int fd[MAX_NR_CPUS][MAX_COUNTERS];

78 static int event_scaled[MAX_COUNTERS];

80 struct stats

81 {

82 double n, mean, M2;

83 };

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

86 {

87 double delta;

89 stats->n++;

90 delta = val - stats->mean;

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

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

93 }

95 static double avg_stats(struct stats *stats)

96 {

97 return stats->mean;

98 }

100 /*

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

102 *

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

104 * s^2 = -------------------------------

105 * n - 1

106 *

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

108 *

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

110 *

111 * s

112 * s_mean = -------

113 * sqrt(n)

114 *

115 */

116 static double stddev_stats(struct stats *stats)

117 {

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

119 double variance_mean = variance / stats->n;

120

121 return sqrt(variance_mean);

122 }

123

124 struct stats event_res_stats[MAX_COUNTERS][3];

125 struct stats runtime_nsecs_stats;

126 struct stats walltime_nsecs_stats;

127 struct stats runtime_cycles_stats;

128 struct stats runtime_branches_stats;

129

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

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

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

133

134 #define ERR_PERF_OPEN \

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

136

137 static void create_perf_stat_counter(int counter, int pid)

138 {

139 struct perf_event_attr *attr = attrs + counter;

140

141 if (scale)

142 attr->read_format = PERF_FORMAT_TOTAL_TIME_ENABLED |

143 PERF_FORMAT_TOTAL_TIME_RUNNING;

144

145 if (system_wide) {

146 unsigned int cpu;

147

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

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

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

151 fprintf(stderr, ERR_PERF_OPEN, counter,

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

153 }

154 } else {

155 attr->inherit = inherit;

156 attr->disabled = 1;

157 attr->enable_on_exec = 1;

158

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

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

161 fprintf(stderr, ERR_PERF_OPEN, counter,

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

163 }

164 }

165

166 /*

167 * Does the counter have nsecs as a unit?

168 */

169 static inline int nsec_counter(int counter)

170 {

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

172 MATCH_EVENT(SOFTWARE, SW_TASK_CLOCK, counter))

173 return 1;

174

175 return 0;

176 }

177

178 /*

179 * Read out the results of a single counter:

180 */

181 static void read_counter(int counter)

182 {

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

184 unsigned int cpu;

185 size_t res, nv;

186 int scaled;

187 int i;

188

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

190

191 nv = scale ? 3 : 1;

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

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

194 continue;

195

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

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

198

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

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

201

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

203 if (scale) {

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

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

206 }

207 }

208

209 scaled = 0;

210 if (scale) {

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

212 event_scaled[counter] = -1;

213 count[0] = 0;

214 return;

215 }

216

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

218 event_scaled[counter] = 1;

219 count[0] = (unsigned long long)

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

221 }

222 }

223

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

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

226

227 if (verbose) {

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

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

230 }

231

232 /*

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

234 */

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

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

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

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

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

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

241 }

242

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

244 {

245 unsigned long long t0, t1;

246 int status = 0;

247 int counter;

248 int pid;

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

250 char buf;

251

252 if (!system_wide)

253 nr_cpus = 1;

254

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

256 perror("failed to create pipes");

257 exit(1);

258 }

259

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

261 perror("failed to fork");

262

263 if (!pid) {

264 close(child_ready_pipe[0]);

265 close(go_pipe[1]);

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

267

268 /*

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

270 * so we avoid the resolver overhead on the real

271 * execvp call.

272 */

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

274

275 /*

276 * Tell the parent we're ready to go

277 */

278 close(child_ready_pipe[1]);

279

280 /*

281 * Wait until the parent tells us to go.

282 */

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

284 perror("unable to read pipe");

285

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

287

288 perror(argv[0]);

289 exit(-1);

290 }

291

292 child_pid = pid;

293

294 /*

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

296 */

297 close(child_ready_pipe[1]);

298 close(go_pipe[0]);

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

300 perror("unable to read pipe");

301 close(child_ready_pipe[0]);

302

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

304 create_perf_stat_counter(counter, pid);

305

306 /*

307 * Enable counters and exec the command:

308 */

309 t0 = rdclock();

310

311 close(go_pipe[1]);

312 wait(&status);

313

314 t1 = rdclock();

315

316 update_stats(&walltime_nsecs_stats, t1 - t0);

317

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

319 read_counter(counter);

320

321 return WEXITSTATUS(status);

322 }

323

324 static void print_noise(int counter, double avg)

325 {

326 if (run_count == 1)

327 return;

328

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

330 100 * stddev_stats(&event_res_stats[counter][0]) / avg);

331 }

332

333 static void nsec_printout(int counter, double avg)

334 {

335 double msecs = avg / 1e6;

336

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

338

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

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

341 avg / avg_stats(&walltime_nsecs_stats));

342 }

343 }

344

345 static void abs_printout(int counter, double avg)

346 {

347 double total, ratio = 0.0;

348

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

350

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

352 total = avg_stats(&runtime_cycles_stats);

353

354 if (total)

355 ratio = avg / total;

356

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

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

359 total = avg_stats(&runtime_branches_stats);

360

361 if (total)

362 ratio = avg * 100 / total;

363

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

365

366 } else {

367 total = avg_stats(&runtime_nsecs_stats);

368

369 if (total)

370 ratio = 1000.0 * avg / total;

371

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

373 }

374 }

375

376 /*

377 * Print out the results of a single counter:

378 */

379 static void print_counter(int counter)

380 {

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

382 int scaled = event_scaled[counter];

383

384 if (scaled == -1) {

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

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

387 return;

388 }

389

390 if (nsec_counter(counter))

391 nsec_printout(counter, avg);

392 else

393 abs_printout(counter, avg);

394

395 print_noise(counter, avg);

396

397 if (scaled) {

398 double avg_enabled, avg_running;

399

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

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

402

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

404 100 * avg_running / avg_enabled);

405 }

406

407 fprintf(stderr, "\n");

408 }

409

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

411 {

412 int i, counter;

413

414 fflush(stdout);

415

416 fprintf(stderr, "\n");

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

418

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

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

421

422 fprintf(stderr, "\'");

423 if (run_count > 1)

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

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

426

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

428 print_counter(counter);

429

430 fprintf(stderr, "\n");

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

432 avg_stats(&walltime_nsecs_stats)/1e9);

433 if (run_count > 1) {

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

435 100*stddev_stats(&walltime_nsecs_stats) /

436 avg_stats(&walltime_nsecs_stats));

437 }

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

439 }

440

441 static volatile int signr = -1;

442

443 static void skip_signal(int signo)

444 {

445 signr = signo;

446 }

447

448 static void sig_atexit(void)

449 {

450 if (child_pid != -1)

451 kill(child_pid, SIGTERM);

452

453 if (signr == -1)

454 return;

455

456 signal(signr, SIG_DFL);

457 kill(getpid(), signr);

458 }

459

460 static const char * const stat_usage[] = {

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

462 NULL

463 };

464

465 static const struct option options[] = {

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

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

468 parse_events),

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

470 "child tasks inherit counters"),

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

472 "stat events on existing pid"),

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

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

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

476 "scale/normalize counters"),

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

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

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

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

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

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

483 OPT_END()

484 };

485

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

487 {

488 int status;

489

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

491 PARSE_OPT_STOP_AT_NON_OPTION);

492 if (!argc)

493 usage_with_options(stat_usage, options);

494 if (run_count <= 0)

495 usage_with_options(stat_usage, options);

496

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

498 if (!null_run && !nr_counters) {

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

500 nr_counters = ARRAY_SIZE(default_attrs);

501 }

502

503 nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);

504 assert(nr_cpus <= MAX_NR_CPUS);

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

506

507 /*

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

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

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

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

512 */

513 atexit(sig_atexit);

514 signal(SIGINT, skip_signal);

515 signal(SIGALRM, skip_signal);

516 signal(SIGABRT, skip_signal);

517

518 status = 0;

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

520 if (run_count != 1 && verbose)

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

522 status = run_perf_stat(argc, argv);

523 }

524

525 print_stat(argc, argv);

526

527 return status;

528 }