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: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar
parent
44175b6f39
commit
42202dd56c
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@ -43,6 +43,7 @@
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#include "util/parse-events.h"
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#include <sys/prctl.h>
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#include <math.h>
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static struct perf_counter_attr default_attrs[MAX_COUNTERS] = {
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@ -79,12 +80,34 @@ static const unsigned int default_count[] = {
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10000,
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};
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static __u64 event_res[MAX_COUNTERS][3];
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static __u64 event_scaled[MAX_COUNTERS];
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#define MAX_RUN 100
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static __u64 runtime_nsecs;
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static __u64 walltime_nsecs;
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static __u64 runtime_cycles;
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static int run_count = 1;
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static int run_idx = 0;
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static __u64 event_res[MAX_RUN][MAX_COUNTERS][3];
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static __u64 event_scaled[MAX_RUN][MAX_COUNTERS];
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//static __u64 event_hist[MAX_RUN][MAX_COUNTERS][3];
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static __u64 runtime_nsecs[MAX_RUN];
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static __u64 walltime_nsecs[MAX_RUN];
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static __u64 runtime_cycles[MAX_RUN];
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static __u64 event_res_avg[MAX_COUNTERS][3];
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static __u64 event_res_noise[MAX_COUNTERS][3];
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static __u64 event_scaled_avg[MAX_COUNTERS];
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static __u64 runtime_nsecs_avg;
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static __u64 runtime_nsecs_noise;
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static __u64 walltime_nsecs_avg;
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static __u64 walltime_nsecs_noise;
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static __u64 runtime_cycles_avg;
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static __u64 runtime_cycles_noise;
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static void create_perf_stat_counter(int counter)
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{
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@ -140,7 +163,7 @@ static void read_counter(int counter)
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int cpu, nv;
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int scaled;
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count = event_res[counter];
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count = event_res[run_idx][counter];
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count[0] = count[1] = count[2] = 0;
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@ -151,6 +174,8 @@ static void read_counter(int counter)
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res = read(fd[cpu][counter], single_count, nv * sizeof(__u64));
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assert(res == nv * sizeof(__u64));
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close(fd[cpu][counter]);
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fd[cpu][counter] = -1;
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count[0] += single_count[0];
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if (scale) {
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@ -162,13 +187,13 @@ static void read_counter(int counter)
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scaled = 0;
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if (scale) {
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if (count[2] == 0) {
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event_scaled[counter] = -1;
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event_scaled[run_idx][counter] = -1;
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count[0] = 0;
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return;
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}
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if (count[2] < count[1]) {
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event_scaled[counter] = 1;
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event_scaled[run_idx][counter] = 1;
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count[0] = (unsigned long long)
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((double)count[0] * count[1] / count[2] + 0.5);
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}
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@ -178,82 +203,18 @@ static void read_counter(int counter)
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*/
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if (attrs[counter].type == PERF_TYPE_SOFTWARE &&
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attrs[counter].config == PERF_COUNT_SW_TASK_CLOCK)
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runtime_nsecs = count[0];
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runtime_nsecs[run_idx] = count[0];
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if (attrs[counter].type == PERF_TYPE_HARDWARE &&
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attrs[counter].config == PERF_COUNT_HW_CPU_CYCLES)
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runtime_cycles = count[0];
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runtime_cycles[run_idx] = count[0];
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}
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static void nsec_printout(int counter, __u64 *count)
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{
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double msecs = (double)count[0] / 1000000;
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fprintf(stderr, " %14.6f %-20s", msecs, event_name(counter));
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if (attrs[counter].type == PERF_TYPE_SOFTWARE &&
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attrs[counter].config == PERF_COUNT_SW_TASK_CLOCK) {
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if (walltime_nsecs)
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fprintf(stderr, " # %10.3f CPUs",
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(double)count[0] / (double)walltime_nsecs);
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}
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}
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static void abs_printout(int counter, __u64 *count)
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{
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fprintf(stderr, " %14Ld %-20s", count[0], event_name(counter));
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if (runtime_cycles &&
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attrs[counter].type == PERF_TYPE_HARDWARE &&
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attrs[counter].config == PERF_COUNT_HW_INSTRUCTIONS) {
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fprintf(stderr, " # %10.3f IPC",
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(double)count[0] / (double)runtime_cycles);
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return;
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}
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if (runtime_nsecs)
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fprintf(stderr, " # %10.3f M/sec",
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(double)count[0]/runtime_nsecs*1000.0);
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}
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/*
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* Print out the results of a single counter:
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*/
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static void print_counter(int counter)
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{
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__u64 *count;
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int scaled;
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count = event_res[counter];
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scaled = event_scaled[counter];
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if (scaled == -1) {
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fprintf(stderr, " %14s %-20s\n",
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"<not counted>", event_name(counter));
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return;
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}
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if (nsec_counter(counter))
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nsec_printout(counter, count);
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else
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abs_printout(counter, count);
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if (scaled)
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fprintf(stderr, " (scaled from %.2f%%)",
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(double) count[2] / count[1] * 100);
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fprintf(stderr, "\n");
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}
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static int do_perf_stat(int argc, const char **argv)
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static int run_perf_stat(int argc, const char **argv)
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{
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unsigned long long t0, t1;
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int status = 0;
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int counter;
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int status;
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int pid;
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int i;
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if (!system_wide)
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nr_cpus = 1;
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@ -277,13 +238,168 @@ static int do_perf_stat(int argc, const char **argv)
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}
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}
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while (wait(&status) >= 0)
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;
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wait(&status);
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prctl(PR_TASK_PERF_COUNTERS_DISABLE);
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t1 = rdclock();
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walltime_nsecs = t1 - t0;
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walltime_nsecs[run_idx] = t1 - t0;
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for (counter = 0; counter < nr_counters; counter++)
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read_counter(counter);
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return WEXITSTATUS(status);
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}
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static void print_noise(__u64 *count, __u64 *noise)
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{
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if (run_count > 1)
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fprintf(stderr, " ( +- %7.3f%% )",
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(double)noise[0]/(count[0]+1)*100.0);
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}
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static void nsec_printout(int counter, __u64 *count, __u64 *noise)
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{
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double msecs = (double)count[0] / 1000000;
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fprintf(stderr, " %14.6f %-20s", msecs, event_name(counter));
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if (attrs[counter].type == PERF_TYPE_SOFTWARE &&
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attrs[counter].config == PERF_COUNT_SW_TASK_CLOCK) {
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if (walltime_nsecs_avg)
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fprintf(stderr, " # %10.3f CPUs ",
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(double)count[0] / (double)walltime_nsecs_avg);
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}
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print_noise(count, noise);
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}
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static void abs_printout(int counter, __u64 *count, __u64 *noise)
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{
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fprintf(stderr, " %14Ld %-20s", count[0], event_name(counter));
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if (runtime_cycles_avg &&
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attrs[counter].type == PERF_TYPE_HARDWARE &&
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attrs[counter].config == PERF_COUNT_HW_INSTRUCTIONS) {
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fprintf(stderr, " # %10.3f IPC ",
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(double)count[0] / (double)runtime_cycles_avg);
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} else {
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if (runtime_nsecs_avg) {
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fprintf(stderr, " # %10.3f M/sec",
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(double)count[0]/runtime_nsecs_avg*1000.0);
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}
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}
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print_noise(count, noise);
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}
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/*
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* Print out the results of a single counter:
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*/
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static void print_counter(int counter)
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{
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__u64 *count, *noise;
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int scaled;
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count = event_res_avg[counter];
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noise = event_res_noise[counter];
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scaled = event_scaled_avg[counter];
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if (scaled == -1) {
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fprintf(stderr, " %14s %-20s\n",
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"<not counted>", event_name(counter));
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return;
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}
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if (nsec_counter(counter))
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nsec_printout(counter, count, noise);
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else
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abs_printout(counter, count, noise);
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if (scaled)
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fprintf(stderr, " (scaled from %.2f%%)",
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(double) count[2] / count[1] * 100);
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fprintf(stderr, "\n");
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}
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/*
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* Normalize noise values down to stddev:
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*/
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static void normalize(__u64 *val)
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{
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double res;
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res = (double)*val / (run_count * sqrt((double)run_count));
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*val = (__u64)res;
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}
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/*
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* Calculate the averages and noises:
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*/
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static void calc_avg(void)
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{
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int i, j;
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for (i = 0; i < run_count; i++) {
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runtime_nsecs_avg += runtime_nsecs[i];
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walltime_nsecs_avg += walltime_nsecs[i];
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runtime_cycles_avg += runtime_cycles[i];
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for (j = 0; j < nr_counters; j++) {
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event_res_avg[j][0] += event_res[i][j][0];
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event_res_avg[j][1] += event_res[i][j][1];
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event_res_avg[j][2] += event_res[i][j][2];
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event_scaled_avg[j] += event_scaled[i][j];
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}
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}
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runtime_nsecs_avg /= run_count;
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walltime_nsecs_avg /= run_count;
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runtime_cycles_avg /= run_count;
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for (j = 0; j < nr_counters; j++) {
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event_res_avg[j][0] /= run_count;
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event_res_avg[j][1] /= run_count;
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event_res_avg[j][2] /= run_count;
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}
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for (i = 0; i < run_count; i++) {
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runtime_nsecs_noise +=
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abs((__s64)(runtime_nsecs[i] - runtime_nsecs_avg));
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walltime_nsecs_noise +=
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abs((__s64)(walltime_nsecs[i] - walltime_nsecs_avg));
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runtime_cycles_noise +=
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abs((__s64)(runtime_cycles[i] - runtime_cycles_avg));
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for (j = 0; j < nr_counters; j++) {
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event_res_noise[j][0] +=
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abs((__s64)(event_res[i][j][0] - event_res_avg[j][0]));
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event_res_noise[j][1] +=
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abs((__s64)(event_res[i][j][1] - event_res_avg[j][1]));
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event_res_noise[j][2] +=
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abs((__s64)(event_res[i][j][2] - event_res_avg[j][2]));
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}
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}
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normalize(&runtime_nsecs_noise);
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normalize(&walltime_nsecs_noise);
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normalize(&runtime_cycles_noise);
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for (j = 0; j < nr_counters; j++) {
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normalize(&event_res_noise[j][0]);
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normalize(&event_res_noise[j][1]);
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normalize(&event_res_noise[j][2]);
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}
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}
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static void print_stat(int argc, const char **argv)
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{
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int i, counter;
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calc_avg();
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run_idx = 0;
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fflush(stdout);
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@ -293,21 +409,19 @@ static int do_perf_stat(int argc, const char **argv)
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for (i = 1; i < argc; i++)
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fprintf(stderr, " %s", argv[i]);
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fprintf(stderr, "\':\n");
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fprintf(stderr, "\n");
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for (counter = 0; counter < nr_counters; counter++)
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read_counter(counter);
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fprintf(stderr, "\'");
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if (run_count > 1)
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fprintf(stderr, " (%d runs)", run_count);
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fprintf(stderr, ":\n\n");
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for (counter = 0; counter < nr_counters; counter++)
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print_counter(counter);
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fprintf(stderr, "\n");
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fprintf(stderr, " %14.9f seconds time elapsed.\n", (double)(t1-t0)/1e9);
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fprintf(stderr, " %14.9f seconds time elapsed.\n",
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(double)walltime_nsecs_avg/1e9);
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fprintf(stderr, "\n");
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return 0;
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}
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static volatile int signr = -1;
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@ -345,11 +459,15 @@ static const struct option options[] = {
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"scale/normalize counters"),
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OPT_BOOLEAN('v', "verbose", &verbose,
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"be more verbose (show counter open errors, etc)"),
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OPT_INTEGER('r', "repeat", &run_count,
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"repeat command and print average + stddev (max: 100)"),
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OPT_END()
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};
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int cmd_stat(int argc, const char **argv, const char *prefix)
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{
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int status;
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page_size = sysconf(_SC_PAGE_SIZE);
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memcpy(attrs, default_attrs, sizeof(attrs));
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@ -357,6 +475,8 @@ int cmd_stat(int argc, const char **argv, const char *prefix)
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argc = parse_options(argc, argv, options, stat_usage, 0);
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if (!argc)
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usage_with_options(stat_usage, options);
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if (run_count <= 0 || run_count > MAX_RUN)
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usage_with_options(stat_usage, options);
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if (!nr_counters)
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nr_counters = 8;
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@ -376,5 +496,14 @@ int cmd_stat(int argc, const char **argv, const char *prefix)
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signal(SIGALRM, skip_signal);
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signal(SIGABRT, skip_signal);
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return do_perf_stat(argc, argv);
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status = 0;
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for (run_idx = 0; run_idx < run_count; run_idx++) {
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if (run_count != 1 && verbose)
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fprintf(stderr, "[ perf stat: executing run #%d ... ]\n", run_idx+1);
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status = run_perf_stat(argc, argv);
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}
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print_stat(argc, argv);
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return status;
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}
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