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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_event_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 { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS },
63 { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_BRANCH_MISSES },
64
65 };
66
67 static int system_wide = 0;
68 static unsigned int nr_cpus = 0;
69 static int run_idx = 0;
70
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;
77
78 static int fd[MAX_NR_CPUS][MAX_COUNTERS];
79
80 static int event_scaled[MAX_COUNTERS];
81
82 struct stats
83 {
84 double n, mean, M2;
85 };
86
87 static void update_stats(struct stats *stats, u64 val)
88 {
89 double delta;
90
91 stats->n++;
92 delta = val - stats->mean;
93 stats->mean += delta / stats->n;
94 stats->M2 += delta*(val - stats->mean);
95 }
96
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 }