From 506d4bc8d5dab20d84624aa07cdc6dcd77915d52 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 4 Sep 2009 15:36:12 +0200 Subject: perf stat: Change noise calculation to use stddev The current noise computation does: \Sum abs(n_i - avg(n)) * N^-1.5 Which is (afaik) not a regular noise function, and needs the complete sample set available to post-process. Change this to use a regular stddev computation which can be done by keeping a two sums: stddev = sqrt( 1/N (\Sum n_i^2) - avg(n)^2 ) For which we only need to keep \Sum n_i and \Sum n_i^2. Signed-off-by: Peter Zijlstra Cc: LKML-Reference: Signed-off-by: Ingo Molnar --- tools/perf/builtin-stat.c | 170 +++++++++++++++++++--------------------------- 1 file changed, 69 insertions(+), 101 deletions(-) (limited to 'tools') diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index 1a2626230660..31ffc4d3ba60 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -83,19 +83,32 @@ static u64 runtime_cycles[MAX_RUN]; static u64 event_res[MAX_RUN][MAX_COUNTERS][3]; static u64 event_scaled[MAX_RUN][MAX_COUNTERS]; -static u64 event_res_avg[MAX_COUNTERS][3]; -static u64 event_res_noise[MAX_COUNTERS][3]; +struct stats +{ + double sum; + double sum_sq; +}; -static u64 event_scaled_avg[MAX_COUNTERS]; +static double avg_stats(struct stats *stats) +{ + return stats->sum / run_count; +} -static u64 runtime_nsecs_avg; -static u64 runtime_nsecs_noise; +/* + * stddev = sqrt(1/N (\Sum n_i^2) - avg(n)^2) + */ +static double stddev_stats(struct stats *stats) +{ + double avg = stats->sum / run_count; -static u64 walltime_nsecs_avg; -static u64 walltime_nsecs_noise; + return sqrt(stats->sum_sq/run_count - avg*avg); +} -static u64 runtime_cycles_avg; -static u64 runtime_cycles_noise; +struct stats event_res_stats[MAX_COUNTERS][3]; +struct stats event_scaled_stats[MAX_COUNTERS]; +struct stats runtime_nsecs_stats; +struct stats walltime_nsecs_stats; +struct stats runtime_cycles_stats; #define MATCH_EVENT(t, c, counter) \ (attrs[counter].type == PERF_TYPE_##t && \ @@ -279,42 +292,37 @@ static int run_perf_stat(int argc __used, const char **argv) return WEXITSTATUS(status); } -static void print_noise(u64 *count, u64 *noise) +static void print_noise(double avg, double stddev) { if (run_count > 1) - fprintf(stderr, " ( +- %7.3f%% )", - (double)noise[0]/(count[0]+1)*100.0); + fprintf(stderr, " ( +- %7.3f%% )", 100*stddev / avg); } -static void nsec_printout(int counter, u64 *count, u64 *noise) +static void nsec_printout(int counter, double avg, double stddev) { - double msecs = (double)count[0] / 1000000; + double msecs = avg / 1e6; fprintf(stderr, " %14.6f %-24s", msecs, event_name(counter)); if (MATCH_EVENT(SOFTWARE, SW_TASK_CLOCK, counter)) { - if (walltime_nsecs_avg) - fprintf(stderr, " # %10.3f CPUs ", - (double)count[0] / (double)walltime_nsecs_avg); + fprintf(stderr, " # %10.3f CPUs ", + avg / avg_stats(&walltime_nsecs_stats)); } - print_noise(count, noise); + print_noise(avg, stddev); } -static void abs_printout(int counter, u64 *count, u64 *noise) +static void abs_printout(int counter, double avg, double stddev) { - fprintf(stderr, " %14Ld %-24s", count[0], event_name(counter)); + fprintf(stderr, " %14.0f %-24s", avg, event_name(counter)); - if (runtime_cycles_avg && - MATCH_EVENT(HARDWARE, HW_INSTRUCTIONS, counter)) { + if (MATCH_EVENT(HARDWARE, HW_INSTRUCTIONS, counter)) { fprintf(stderr, " # %10.3f IPC ", - (double)count[0] / (double)runtime_cycles_avg); + avg / avg_stats(&runtime_cycles_stats)); } else { - if (runtime_nsecs_avg) { - fprintf(stderr, " # %10.3f M/sec", - (double)count[0]/runtime_nsecs_avg*1000.0); - } + fprintf(stderr, " # %10.3f M/sec", + 1000.0 * avg / avg_stats(&runtime_nsecs_stats)); } - print_noise(count, noise); + print_noise(avg, stddev); } /* @@ -322,12 +330,12 @@ static void abs_printout(int counter, u64 *count, u64 *noise) */ static void print_counter(int counter) { - u64 *count, *noise; + double avg, stddev; int scaled; - count = event_res_avg[counter]; - noise = event_res_noise[counter]; - scaled = event_scaled_avg[counter]; + avg = avg_stats(&event_res_stats[counter][0]); + stddev = stddev_stats(&event_res_stats[counter][0]); + scaled = avg_stats(&event_scaled_stats[counter]); if (scaled == -1) { fprintf(stderr, " %14s %-24s\n", @@ -336,36 +344,34 @@ static void print_counter(int counter) } if (nsec_counter(counter)) - nsec_printout(counter, count, noise); + nsec_printout(counter, avg, stddev); else - abs_printout(counter, count, noise); + abs_printout(counter, avg, stddev); + + if (scaled) { + double avg_enabled, avg_running; + + avg_enabled = avg_stats(&event_res_stats[counter][1]); + avg_running = avg_stats(&event_res_stats[counter][2]); - if (scaled) fprintf(stderr, " (scaled from %.2f%%)", - (double) count[2] / count[1] * 100); + 100 * avg_running / avg_enabled); + } fprintf(stderr, "\n"); } -/* - * normalize_noise noise values down to stddev: - */ -static void normalize_noise(u64 *val) +static void update_stats(const char *name, int idx, struct stats *stats, u64 *val) { - double res; + double sq = *val; - res = (double)*val / (run_count * sqrt((double)run_count)); - - *val = (u64)res; -} - -static void update_avg(const char *name, int idx, u64 *avg, u64 *val) -{ - *avg += *val; + stats->sum += *val; + stats->sum_sq += sq * sq; if (verbose > 1) fprintf(stderr, "debug: %20s[%d]: %Ld\n", name, idx, *val); } + /* * Calculate the averages and noises: */ @@ -377,61 +383,22 @@ static void calc_avg(void) fprintf(stderr, "\n"); for (i = 0; i < run_count; i++) { - update_avg("runtime", 0, &runtime_nsecs_avg, runtime_nsecs + i); - update_avg("walltime", 0, &walltime_nsecs_avg, walltime_nsecs + i); - update_avg("runtime_cycles", 0, &runtime_cycles_avg, runtime_cycles + i); + update_stats("runtime", 0, &runtime_nsecs_stats, runtime_nsecs + i); + update_stats("walltime", 0, &walltime_nsecs_stats, walltime_nsecs + i); + update_stats("runtime_cycles", 0, &runtime_cycles_stats, runtime_cycles + i); for (j = 0; j < nr_counters; j++) { - update_avg("counter/0", j, - event_res_avg[j]+0, event_res[i][j]+0); - update_avg("counter/1", j, - event_res_avg[j]+1, event_res[i][j]+1); - update_avg("counter/2", j, - event_res_avg[j]+2, event_res[i][j]+2); + update_stats("counter/0", j, + event_res_stats[j]+0, event_res[i][j]+0); + update_stats("counter/1", j, + event_res_stats[j]+1, event_res[i][j]+1); + update_stats("counter/2", j, + event_res_stats[j]+2, event_res[i][j]+2); if (event_scaled[i][j] != (u64)-1) - update_avg("scaled", j, - event_scaled_avg + j, event_scaled[i]+j); - else - event_scaled_avg[j] = -1; + update_stats("scaled", j, + event_scaled_stats + 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; - } - - 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])); - } - } - - normalize_noise(&runtime_nsecs_noise); - normalize_noise(&walltime_nsecs_noise); - normalize_noise(&runtime_cycles_noise); - - for (j = 0; j < nr_counters; j++) { - normalize_noise(&event_res_noise[j][0]); - normalize_noise(&event_res_noise[j][1]); - normalize_noise(&event_res_noise[j][2]); - } } static void print_stat(int argc, const char **argv) @@ -458,10 +425,11 @@ static void print_stat(int argc, const char **argv) fprintf(stderr, "\n"); fprintf(stderr, " %14.9f seconds time elapsed", - (double)walltime_nsecs_avg/1e9); + avg_stats(&walltime_nsecs_stats)/1e9); if (run_count > 1) { fprintf(stderr, " ( +- %7.3f%% )", - 100.0*(double)walltime_nsecs_noise/(double)walltime_nsecs_avg); + 100*stddev_stats(&walltime_nsecs_stats) / + avg_stats(&walltime_nsecs_stats)); } fprintf(stderr, "\n\n"); } -- cgit v1.2.3-58-ga151