From 9d6a1df9b2eef52ad03a594b1237a16dbbe34e83 Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Sat, 27 May 2023 00:22:05 -0700 Subject: perf pmus: Allow just core PMU scanning Scanning all PMUs is expensive as all PMUs sysfs entries are loaded, benchmarking shows more than 4x the cost: ``` $ perf bench internals pmu-scan -i 1000 Computing performance of sysfs PMU event scan for 1000 times Average core PMU scanning took: 989.231 usec (+- 1.535 usec) Average PMU scanning took: 4309.425 usec (+- 74.322 usec) ``` Add new perf_pmus__scan_core routine that scans just core PMUs. Replace perf_pmus__scan calls with perf_pmus__scan_core when non-core PMUs are being ignored. Reviewed-by: Kan Liang Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ali Saidi Cc: Athira Rajeev Cc: Dmitrii Dolgov <9erthalion6@gmail.com> Cc: Huacai Chen Cc: Ingo Molnar Cc: James Clark Cc: Jing Zhang Cc: Jiri Olsa Cc: John Garry Cc: Kajol Jain Cc: Kang Minchul Cc: Leo Yan Cc: Madhavan Srinivasan Cc: Mark Rutland Cc: Mike Leach Cc: Ming Wang Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Rob Herring Cc: Sandipan Das Cc: Sean Christopherson Cc: Suzuki Poulouse Cc: Thomas Richter Cc: Will Deacon Cc: Xing Zhengjun Cc: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Link: https://lore.kernel.org/r/20230527072210.2900565-30-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/bench/pmu-scan.c | 50 ++++++++++++++++++++++++++------------------- 1 file changed, 29 insertions(+), 21 deletions(-) (limited to 'tools/perf/bench') diff --git a/tools/perf/bench/pmu-scan.c b/tools/perf/bench/pmu-scan.c index 51cae2d03353..c7d207f8e13c 100644 --- a/tools/perf/bench/pmu-scan.c +++ b/tools/perf/bench/pmu-scan.c @@ -22,6 +22,7 @@ struct pmu_scan_result { int nr_aliases; int nr_formats; int nr_caps; + bool is_core; }; static const struct option options[] = { @@ -53,6 +54,7 @@ static int save_result(void) r = results + nr_pmus; r->name = strdup(pmu->name); + r->is_core = pmu->is_core; r->nr_caps = pmu->nr_caps; r->nr_aliases = 0; @@ -72,7 +74,7 @@ static int save_result(void) return 0; } -static int check_result(void) +static int check_result(bool core_only) { struct pmu_scan_result *r; struct perf_pmu *pmu; @@ -81,6 +83,9 @@ static int check_result(void) for (int i = 0; i < nr_pmus; i++) { r = &results[i]; + if (core_only && !r->is_core) + continue; + pmu = perf_pmus__find(r->name); if (pmu == NULL) { pr_err("Cannot find PMU %s\n", r->name); @@ -130,7 +135,6 @@ static int run_pmu_scan(void) struct timeval start, end, diff; double time_average, time_stddev; u64 runtime_us; - unsigned int i; int ret; init_stats(&stats); @@ -142,26 +146,30 @@ static int run_pmu_scan(void) return -1; } - for (i = 0; i < iterations; i++) { - gettimeofday(&start, NULL); - perf_pmus__scan(NULL); - gettimeofday(&end, NULL); - - timersub(&end, &start, &diff); - runtime_us = diff.tv_sec * USEC_PER_SEC + diff.tv_usec; - update_stats(&stats, runtime_us); - - ret = check_result(); - perf_pmus__destroy(); - if (ret < 0) - break; + for (int j = 0; j < 2; j++) { + bool core_only = (j == 0); + + for (unsigned int i = 0; i < iterations; i++) { + gettimeofday(&start, NULL); + if (core_only) + perf_pmus__scan_core(NULL); + else + perf_pmus__scan(NULL); + gettimeofday(&end, NULL); + timersub(&end, &start, &diff); + runtime_us = diff.tv_sec * USEC_PER_SEC + diff.tv_usec; + update_stats(&stats, runtime_us); + + ret = check_result(core_only); + perf_pmus__destroy(); + if (ret < 0) + break; + } + time_average = avg_stats(&stats); + time_stddev = stddev_stats(&stats); + pr_info(" Average%s PMU scanning took: %.3f usec (+- %.3f usec)\n", + core_only ? " core" : "", time_average, time_stddev); } - - time_average = avg_stats(&stats); - time_stddev = stddev_stats(&stats); - pr_info(" Average PMU scanning took: %.3f usec (+- %.3f usec)\n", - time_average, time_stddev); - delete_result(); return 0; } -- cgit v1.3.1