Commit f6a7bbbf authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

perf bench: Add pmu-scan benchmark 



The pmu-scan benchmark will repeatedly scan the sysfs to get the
available PMU information.

  $ ./perf bench internals pmu-scan
  # Running 'internals/pmu-scan' benchmark:
  Computing performance of sysfs PMU event scan for 100 times
    Average PMU scanning took: 6850.990 usec (+- 48.445 usec)

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Acked-by: default avatarIan Rogers <irogers@google.com>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230331202949.810326-2-namhyung@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent eec11310

tools/perf/bench/Build

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ perf-y += find-bit-bench.o 
perf-y += inject-buildid.o

perf-y += evlist-open-close.o

perf-y += breakpoint.o

perf-y += pmu-scan.o



perf-$(CONFIG_X86_64) += mem-memcpy-x86-64-asm.o

perf-$(CONFIG_X86_64) += mem-memset-x86-64-asm.o

tools/perf/bench/bench.h

+1 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ int bench_inject_build_id(int argc, const char **argv); 
int bench_evlist_open_close(int argc, const char **argv);

int bench_breakpoint_thread(int argc, const char **argv);

int bench_breakpoint_enable(int argc, const char **argv);

int bench_pmu_scan(int argc, const char **argv);



#define BENCH_FORMAT_DEFAULT_STR	"default"

#define BENCH_FORMAT_DEFAULT		0

tools/perf/bench/pmu-scan.c

0 → 100644
+184 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Benchmark scanning sysfs files for PMU information.

 *

 * Copyright 2023 Google LLC.

 */

#include <stdio.h>

#include "bench.h"

#include "util/debug.h"

#include "util/pmu.h"

#include "util/pmus.h"

#include "util/stat.h"

#include <linux/atomic.h>

#include <linux/err.h>

#include <linux/time64.h>

#include <subcmd/parse-options.h>



static unsigned int iterations = 100;



struct pmu_scan_result {

	char *name;

	int nr_aliases;

	int nr_formats;

	int nr_caps;

};



static const struct option options[] = {

	OPT_UINTEGER('i', "iterations", &iterations,

		"Number of iterations used to compute average"),

	OPT_END()

};



static const char *const bench_usage[] = {

	"perf bench internals pmu-scan <options>",

	NULL

};



static int nr_pmus;

static struct pmu_scan_result *results;



static int save_result(void)

{

	struct perf_pmu *pmu;

	struct list_head *list;

	struct pmu_scan_result *r;



	perf_pmu__scan(NULL);



	perf_pmus__for_each_pmu(pmu) {

		r = realloc(results, (nr_pmus + 1) * sizeof(*r));

		if (r == NULL)

			return -ENOMEM;



		results = r;

		r = results + nr_pmus;



		r->name = strdup(pmu->name);

		r->nr_caps = pmu->nr_caps;



		r->nr_aliases = 0;

		list_for_each(list, &pmu->aliases)

			r->nr_aliases++;



		r->nr_formats = 0;

		list_for_each(list, &pmu->format)

			r->nr_formats++;



		pr_debug("pmu[%d] name=%s, nr_caps=%d, nr_aliases=%d, nr_formats=%d\n",

			nr_pmus, r->name, r->nr_caps, r->nr_aliases, r->nr_formats);

		nr_pmus++;

	}



	perf_pmu__destroy();

	return 0;

}



static int check_result(void)

{

	struct pmu_scan_result *r;

	struct perf_pmu *pmu;

	struct list_head *list;

	int nr;



	for (int i = 0; i < nr_pmus; i++) {

		r = &results[i];

		pmu = perf_pmu__find(r->name);

		if (pmu == NULL) {

			pr_err("Cannot find PMU %s\n", r->name);

			return -1;

		}



		if (pmu->nr_caps != (u32)r->nr_caps) {

			pr_err("Unmatched number of event caps in %s: expect %d vs got %d\n",

				pmu->name, r->nr_caps, pmu->nr_caps);

			return -1;

		}



		nr = 0;

		list_for_each(list, &pmu->aliases)

			nr++;

		if (nr != r->nr_aliases) {

			pr_err("Unmatched number of event aliases in %s: expect %d vs got %d\n",

				pmu->name, r->nr_aliases, nr);

			return -1;

		}



		nr = 0;

		list_for_each(list, &pmu->format)

			nr++;

		if (nr != r->nr_formats) {

			pr_err("Unmatched number of event formats in %s: expect %d vs got %d\n",

				pmu->name, r->nr_formats, nr);

			return -1;

		}

	}

	return 0;

}



static void delete_result(void)

{

	for (int i = 0; i < nr_pmus; i++)

		free(results[i].name);

	free(results);



	results = NULL;

	nr_pmus = 0;

}



static int run_pmu_scan(void)

{

	struct stats stats;

	struct timeval start, end, diff;

	double time_average, time_stddev;

	u64 runtime_us;

	unsigned int i;

	int ret;



	init_stats(&stats);

	pr_info("Computing performance of sysfs PMU event scan for %u times\n",

		iterations);



	if (save_result() < 0) {

		pr_err("Failed to initialize PMU scan result\n");

		return -1;

	}



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

		gettimeofday(&start, NULL);

		perf_pmu__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_pmu__destroy();

		if (ret < 0)

			break;

	}



	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;

}



int bench_pmu_scan(int argc, const char **argv)

{

	int err = 0;



	argc = parse_options(argc, argv, options, bench_usage, 0);

	if (argc) {

		usage_with_options(bench_usage, options);

		exit(EXIT_FAILURE);

	}



	err = run_pmu_scan();



	return err;

}

tools/perf/builtin-bench.c

+1 −0
Original line number Diff line number Diff line
@@ -92,6 +92,7 @@ static struct bench internals_benchmarks[] = { 
	{ "kallsyms-parse", "Benchmark kallsyms parsing",	bench_kallsyms_parse	},

	{ "inject-build-id", "Benchmark build-id injection",	bench_inject_build_id	},

	{ "evlist-open-close", "Benchmark evlist open and close",	bench_evlist_open_close	},

	{ "pmu-scan", "Benchmark sysfs PMU info scanning",	bench_pmu_scan		},

	{ NULL,		NULL,					NULL			}

};