Commit 42202dd5 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

perf stat: Add feature to run and measure a command multiple times 



Add the --repeat <n> feature to perf stat, which repeats a given
command up to a 100 times, collects the stats and calculates an
average and a stddev.

For example, the following oneliner 'perf stat' command runs hackbench
5 times and prints a tabulated result of all metrics, with averages
and noise levels (in percentage) printed:

 aldebaran:~/linux/linux/tools/perf> ./perf stat --repeat 5 ~/hackbench 10
 Time: 0.117
 Time: 0.108
 Time: 0.089
 Time: 0.088
 Time: 0.100

 Performance counter stats for '/home/mingo/hackbench 10' (5 runs):

    1243.989586  task-clock-msecs     #     10.460 CPUs    ( +-   4.720% )
          47706  context-switches     #      0.038 M/sec   ( +-  19.706% )
            387  CPU-migrations       #      0.000 M/sec   ( +-   3.608% )
          17793  page-faults          #      0.014 M/sec   ( +-   0.354% )
     3770941606  cycles               #   3031.329 M/sec   ( +-   4.621% )
     1566372416  instructions         #      0.415 IPC     ( +-   2.703% )
       16783421  cache-references     #     13.492 M/sec   ( +-   5.202% )
        7128590  cache-misses         #      5.730 M/sec   ( +-   7.420% )

    0.118924455  seconds time elapsed.

The goal of this feature is to allow the reliance on these accurate
statistics and to know how many times a command has to be repeated
for the noise to go down to an acceptable level.

(The -v option can be used to see a line printed out as each run progresses.)

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 44175b6f

tools/perf/builtin-stat.c

+194 −65
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ 
#include "util/parse-events.h"



#include <sys/prctl.h>

#include <math.h>



static struct perf_counter_attr default_attrs[MAX_COUNTERS] = {
@@ -79,12 +80,34 @@ static const unsigned int default_count[] = { 
	  10000,

};



static __u64			event_res[MAX_COUNTERS][3];

static __u64			event_scaled[MAX_COUNTERS];

#define MAX_RUN 100



static __u64			runtime_nsecs;

static __u64			walltime_nsecs;

static __u64			runtime_cycles;

static int			run_count		=  1;

static int			run_idx			=  0;



static __u64			event_res[MAX_RUN][MAX_COUNTERS][3];

static __u64			event_scaled[MAX_RUN][MAX_COUNTERS];



//static __u64			event_hist[MAX_RUN][MAX_COUNTERS][3];





static __u64			runtime_nsecs[MAX_RUN];

static __u64			walltime_nsecs[MAX_RUN];

static __u64			runtime_cycles[MAX_RUN];



static __u64			event_res_avg[MAX_COUNTERS][3];

static __u64			event_res_noise[MAX_COUNTERS][3];



static __u64			event_scaled_avg[MAX_COUNTERS];



static __u64			runtime_nsecs_avg;

static __u64			runtime_nsecs_noise;



static __u64			walltime_nsecs_avg;

static __u64			walltime_nsecs_noise;



static __u64			runtime_cycles_avg;

static __u64			runtime_cycles_noise;



static void create_perf_stat_counter(int counter)

{
@@ -140,7 +163,7 @@ static void read_counter(int counter) 
	int cpu, nv;

	int scaled;



	count = event_res[counter];

	count = event_res[run_idx][counter];



	count[0] = count[1] = count[2] = 0;
@@ -151,6 +174,8 @@ static void read_counter(int counter) 


		res = read(fd[cpu][counter], single_count, nv * sizeof(__u64));

		assert(res == nv * sizeof(__u64));

		close(fd[cpu][counter]);

		fd[cpu][counter] = -1;



		count[0] += single_count[0];

		if (scale) {
@@ -162,13 +187,13 @@ static void read_counter(int counter) 
	scaled = 0;

	if (scale) {

		if (count[2] == 0) {

			event_scaled[counter] = -1;

			event_scaled[run_idx][counter] = -1;

			count[0] = 0;

			return;

		}



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

			event_scaled[counter] = 1;

			event_scaled[run_idx][counter] = 1;

			count[0] = (unsigned long long)

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

		}
@@ -178,13 +203,62 @@ static void read_counter(int counter) 
	 */

	if (attrs[counter].type == PERF_TYPE_SOFTWARE &&

		attrs[counter].config == PERF_COUNT_SW_TASK_CLOCK)

		runtime_nsecs = count[0];

		runtime_nsecs[run_idx] = count[0];

	if (attrs[counter].type == PERF_TYPE_HARDWARE &&

		attrs[counter].config == PERF_COUNT_HW_CPU_CYCLES)

		runtime_cycles = count[0];

		runtime_cycles[run_idx] = count[0];

}



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

{

	unsigned long long t0, t1;

	int status = 0;

	int counter;

	int pid;



	if (!system_wide)

		nr_cpus = 1;



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

		create_perf_stat_counter(counter);



	/*

	 * Enable counters and exec the command:

	 */

	t0 = rdclock();

	prctl(PR_TASK_PERF_COUNTERS_ENABLE);



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

		perror("failed to fork");



	if (!pid) {

		if (execvp(argv[0], (char **)argv)) {

			perror(argv[0]);

			exit(-1);

		}

	}



	wait(&status);



	prctl(PR_TASK_PERF_COUNTERS_DISABLE);

	t1 = rdclock();



	walltime_nsecs[run_idx] = t1 - t0;



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

		read_counter(counter);



	return WEXITSTATUS(status);

}



static void print_noise(__u64 *count, __u64 *noise)

{

	if (run_count > 1)

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

			(double)noise[0]/(count[0]+1)*100.0);

}



static void nsec_printout(int counter, __u64 *count)

static void nsec_printout(int counter, __u64 *count, __u64 *noise)

{

	double msecs = (double)count[0] / 1000000;
@@ -193,29 +267,30 @@ static void nsec_printout(int counter, __u64 *count) 
	if (attrs[counter].type == PERF_TYPE_SOFTWARE &&

		attrs[counter].config == PERF_COUNT_SW_TASK_CLOCK) {



		if (walltime_nsecs)

		if (walltime_nsecs_avg)

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

				(double)count[0] / (double)walltime_nsecs);

				(double)count[0] / (double)walltime_nsecs_avg);

	}

	print_noise(count, noise);

}



static void abs_printout(int counter, __u64 *count)

static void abs_printout(int counter, __u64 *count, __u64 *noise)

{

	fprintf(stderr, " %14Ld  %-20s", count[0], event_name(counter));



	if (runtime_cycles &&

	if (runtime_cycles_avg &&

		attrs[counter].type == PERF_TYPE_HARDWARE &&

			attrs[counter].config == PERF_COUNT_HW_INSTRUCTIONS) {



		fprintf(stderr, " # %10.3f IPC  ",

			(double)count[0] / (double)runtime_cycles);



		return;

	}



	if (runtime_nsecs)

			(double)count[0] / (double)runtime_cycles_avg);

	} else {

		if (runtime_nsecs_avg) {

			fprintf(stderr, " # %10.3f M/sec",

			(double)count[0]/runtime_nsecs*1000.0);

				(double)count[0]/runtime_nsecs_avg*1000.0);

		}

	}

	print_noise(count, noise);

}



/*
@@ -223,11 +298,12 @@ static void abs_printout(int counter, __u64 *count) 
 */

static void print_counter(int counter)

{

	__u64 *count;

	__u64 *count, *noise;

	int scaled;



	count = event_res[counter];

	scaled = event_scaled[counter];

	count = event_res_avg[counter];

	noise = event_res_noise[counter];

	scaled = event_scaled_avg[counter];



	if (scaled == -1) {

		fprintf(stderr, " %14s  %-20s\n",
@@ -236,9 +312,9 @@ static void print_counter(int counter) 
	}



	if (nsec_counter(counter))

		nsec_printout(counter, count);

		nsec_printout(counter, count, noise);

	else

		abs_printout(counter, count);

		abs_printout(counter, count, noise);



	if (scaled)

		fprintf(stderr, "  (scaled from %.2f%%)",
@@ -247,43 +323,83 @@ static void print_counter(int counter) 
	fprintf(stderr, "\n");

}



static int do_perf_stat(int argc, const char **argv)

/*

 * Normalize noise values down to stddev:

 */

static void normalize(__u64 *val)

{

	unsigned long long t0, t1;

	int counter;

	int status;

	int pid;

	int i;

	double res;



	if (!system_wide)

		nr_cpus = 1;

	res = (double)*val / (run_count * sqrt((double)run_count));



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

		create_perf_stat_counter(counter);

	*val = (__u64)res;

}



/*

	 * Enable counters and exec the command:

 * Calculate the averages and noises:

 */

	t0 = rdclock();

	prctl(PR_TASK_PERF_COUNTERS_ENABLE);

static void calc_avg(void)

{

	int i, j;



	for (i = 0; i < run_count; i++) {

		runtime_nsecs_avg += runtime_nsecs[i];

		walltime_nsecs_avg += walltime_nsecs[i];

		runtime_cycles_avg += runtime_cycles[i];



		for (j = 0; j < nr_counters; j++) {

			event_res_avg[j][0] += event_res[i][j][0];

			event_res_avg[j][1] += event_res[i][j][1];

			event_res_avg[j][2] += event_res[i][j][2];

			event_scaled_avg[j] += event_scaled[i][j];

		}

	}

	runtime_nsecs_avg /= run_count;

	walltime_nsecs_avg /= run_count;

	runtime_cycles_avg /= run_count;



	for (j = 0; j < nr_counters; j++) {

		event_res_avg[j][0] /= run_count;

		event_res_avg[j][1] /= run_count;

		event_res_avg[j][2] /= run_count;

	}



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

		perror("failed to fork");

	for (i = 0; i < run_count; i++) {

		runtime_nsecs_noise +=

			abs((__s64)(runtime_nsecs[i] - runtime_nsecs_avg));

		walltime_nsecs_noise +=

			abs((__s64)(walltime_nsecs[i] - walltime_nsecs_avg));

		runtime_cycles_noise +=

			abs((__s64)(runtime_cycles[i] - runtime_cycles_avg));



		for (j = 0; j < nr_counters; j++) {

			event_res_noise[j][0] +=

				abs((__s64)(event_res[i][j][0] - event_res_avg[j][0]));

			event_res_noise[j][1] +=

				abs((__s64)(event_res[i][j][1] - event_res_avg[j][1]));

			event_res_noise[j][2] +=

				abs((__s64)(event_res[i][j][2] - event_res_avg[j][2]));

		}

	}



	if (!pid) {

		if (execvp(argv[0], (char **)argv)) {

			perror(argv[0]);

			exit(-1);

	normalize(&runtime_nsecs_noise);

	normalize(&walltime_nsecs_noise);

	normalize(&runtime_cycles_noise);



	for (j = 0; j < nr_counters; j++) {

		normalize(&event_res_noise[j][0]);

		normalize(&event_res_noise[j][1]);

		normalize(&event_res_noise[j][2]);

	}

}



	while (wait(&status) >= 0)

		;

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

{

	int i, counter;



	prctl(PR_TASK_PERF_COUNTERS_DISABLE);

	t1 = rdclock();

	calc_avg();



	walltime_nsecs = t1 - t0;

	run_idx = 0;



	fflush(stdout);
@@ -293,21 +409,19 @@ static int do_perf_stat(int argc, const char **argv) 
	for (i = 1; i < argc; i++)

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



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

	fprintf(stderr, "\n");



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

		read_counter(counter);

	fprintf(stderr, "\'");

	if (run_count > 1)

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

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



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

		print_counter(counter);





	fprintf(stderr, "\n");

	fprintf(stderr, " %14.9f  seconds time elapsed.\n", (double)(t1-t0)/1e9);

	fprintf(stderr, " %14.9f  seconds time elapsed.\n",

			(double)walltime_nsecs_avg/1e9);

	fprintf(stderr, "\n");



	return 0;

}



static volatile int signr = -1;
@@ -345,11 +459,15 @@ static const struct option options[] = { 
			    "scale/normalize counters"),

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

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

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

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

	OPT_END()

};



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

{

	int status;



	page_size = sysconf(_SC_PAGE_SIZE);



	memcpy(attrs, default_attrs, sizeof(attrs));
@@ -357,6 +475,8 @@ int cmd_stat(int argc, const char **argv, const char *prefix) 
	argc = parse_options(argc, argv, options, stat_usage, 0);

	if (!argc)

		usage_with_options(stat_usage, options);

	if (run_count <= 0 || run_count > MAX_RUN)

		usage_with_options(stat_usage, options);



	if (!nr_counters)

		nr_counters = 8;
@@ -376,5 +496,14 @@ int cmd_stat(int argc, const char **argv, const char *prefix) 
	signal(SIGALRM, skip_signal);

	signal(SIGABRT, skip_signal);



	return do_perf_stat(argc, argv);

	status = 0;

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

		if (run_count != 1 && verbose)

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

		status = run_perf_stat(argc, argv);

	}



	print_stat(argc, argv);



	return status;

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE