Re: [PATCH] perf bench: add benchmark for evlist open/close operations

This new benchmark finds the total time that is taken to open, mmap,
enable, disable, munmap, close an evlist (time taken for new,
create_maps, config, delete is not counted in).
The evlist can be configured as in perf-record using the
-a,-C,-e,-u,--per-thread,-t,-p options.
The events can be duplicated in the evlist to quickly test performance
with many events using the -n options.
Furthermore, also the number of iterations used to calculate the
statistics is customizable.

Examples:
- Open one dummy event system-wide:
$ sudo ./perf bench internals evlist-open-close
  Number of cpus:       4
  Number of threads:    1
  Number of events:     1 (4 fds)
  Number of iterations: 100
  Average open-close took: 613.870 usec (+- 32.852 usec)

- Open the group '{cs,cycles}' on CPU 0
$ sudo ./perf bench internals evlist-open-close -e '{cs,cycles}' -C 0
  Number of cpus:       1
  Number of threads:    1
  Number of events:     2 (2 fds)
  Number of iterations: 100
  Average open-close took: 8503.220 usec (+- 252.652 usec)

- Open 10 'cycles' events for user 0, calculate average over 100 runs
$ sudo ./perf bench internals evlist-open-close -e cycles -n 10 -u 0 -i 100
  Number of cpus:       4
  Number of threads:    328
  Number of events:     10 (13120 fds)
  Number of iterations: 100
  Average open-close took: 180043.140 usec (+- 2295.889 usec)

Signed-off-by: Riccardo Mancini <redacted>
---
 tools/perf/bench/Build               |   1 +
 tools/perf/bench/bench.h             |   1 +
 tools/perf/bench/evlist-open-close.c | 275 +++++++++++++++++++++++++++
 tools/perf/builtin-bench.c           |   1 +
 4 files changed, 278 insertions(+)
 create mode 100644 tools/perf/bench/evlist-open-close.c

diff --git a/tools/perf/bench/Build b/tools/perf/bench/Build
index e43f46931b41b78f..61d45fcb4057c945 100644
--- a/tools/perf/bench/Build
+++ b/tools/perf/bench/Build

@@ -13,6 +13,7 @@ perf-y += synthesize.o
 perf-y += kallsyms-parse.o
 perf-y += find-bit-bench.o
 perf-y += inject-buildid.o
+perf-y += evlist-open-close.o
 
 perf-$(CONFIG_X86_64) += mem-memcpy-x86-64-asm.o
 perf-$(CONFIG_X86_64) += mem-memset-x86-64-asm.o

diff --git a/tools/perf/bench/bench.h b/tools/perf/bench/bench.h
index eac36afab2b39fa5..b3480bc33fe84885 100644
--- a/tools/perf/bench/bench.h
+++ b/tools/perf/bench/bench.h

@@ -48,6 +48,7 @@ int bench_epoll_ctl(int argc, const char **argv);
 int bench_synthesize(int argc, const char **argv);
 int bench_kallsyms_parse(int argc, const char **argv);
 int bench_inject_build_id(int argc, const char **argv);
+int bench_evlist_open_close(int argc, const char **argv);
 
 #define BENCH_FORMAT_DEFAULT_STR	"default"
 #define BENCH_FORMAT_DEFAULT		0

diff --git a/tools/perf/bench/evlist-open-close.c b/tools/perf/bench/evlist-open-close.c
new file mode 100644
index 0000000000000000..40bce06f5ca7bef3
--- /dev/null
+++ b/tools/perf/bench/evlist-open-close.c

@@ -0,0 +1,275 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+#include "bench.h"
+#include "../util/debug.h"
+#include "../util/stat.h"
+#include "../util/evlist.h"
+#include "../util/evsel.h"
+#include "../util/strbuf.h"
+#include "../util/record.h"
+#include "../util/parse-events.h"
+#include "internal/threadmap.h"
+#include "internal/cpumap.h"
+#include <linux/perf_event.h>
+#include <linux/kernel.h>
+#include <linux/time64.h>
+#include <linux/string.h>
+#include <subcmd/parse-options.h>
+
+#define MMAP_FLUSH_DEFAULT 1
+
+static int iterations = 100;
+static int nr_events = 1;
+static const char *event_string = "dummy";
+
+static struct record_opts opts = {
+	.sample_time	     = true,
+	.mmap_pages	     = UINT_MAX,
+	.user_freq	     = UINT_MAX,
+	.user_interval	     = ULLONG_MAX,
+	.freq		     = 4000,
+	.target		     = {
+		.uses_mmap   = true,
+		.default_per_cpu = true,
+	},
+	.mmap_flush          = MMAP_FLUSH_DEFAULT,
+	.nr_threads_synthesize = 1,
+	.ctl_fd              = -1,
+	.ctl_fd_ack          = -1,
+};
+
+static const struct option options[] = {
+	OPT_STRING('e', "event", &event_string, "event",
+		     "event selector. use 'perf list' to list available events"),
+	OPT_INTEGER('n', "nr-events", &nr_events,
+		     "number of dummy events to create (default 1). If used with -e, it clones those events n times (1 = no change)"),
+	OPT_INTEGER('i', "iterations", &iterations,
+		"Number of iterations used to compute average (default=100)"),
+	OPT_BOOLEAN('a', "all-cpus", &opts.target.system_wide,
+		"system-wide collection from all CPUs"),
+	OPT_STRING('C', "cpu", &opts.target.cpu_list, "cpu",
+		    "list of cpus where to open events"),
+	OPT_STRING('p', "pid", &opts.target.pid, "pid",
+		    "record events on existing process id"),
+	OPT_STRING('t', "tid", &opts.target.tid, "tid",
+		    "record events on existing thread id"),
+	OPT_STRING('u', "uid", &opts.target.uid_str, "user",
+		   "user to profile"),
+	OPT_BOOLEAN(0, "per-thread", &opts.target.per_thread,
+		    "use per-thread mmaps"),
+	OPT_END()
+};
+
+static const char *const bench_usage[] = {
+	"perf bench internals evlist-open-close <options>",
+	NULL
+};
+
+static int evlist__count_evsel_fds(struct evlist *evlist)
+{
+	struct evsel *evsel;
+	int cnt = 0;
+
+	evlist__for_each_entry(evlist, evsel) {
+		cnt += evsel->core.threads->nr * evsel->core.cpus->nr;
+	}
+
+	return cnt;
+}
+
+static struct evlist *bench__create_evlist(char *evstr)
+{
+	struct evlist *evlist;
+	struct parse_events_error err;
+	int ret;
+
+	evlist = evlist__new();
+	if (!evlist) {
+		pr_err("Not enough memory to create evlist\n");
+		return NULL;
+	}
+
+	bzero(&err, sizeof(err));

+	ret = parse_events(evlist, evstr, &err);
+	if (ret) {
+		parse_events_print_error(&err, evstr);
+		pr_err("Run 'perf list' for a list of valid events\n");
+		ret = 1;
+		goto out_delete_evlist;
+	}
+
+	ret = evlist__create_maps(evlist, &opts.target);
+	if (ret < 0) {
+		pr_err("Not enough memory to create thread/cpu maps\n");
+		goto out_delete_evlist;
+	}
+
+	evlist__config(evlist, &opts, NULL);
+
+	return evlist;
+
+out_delete_evlist:
+	evlist__delete(evlist);
+	return NULL;
+}
+
+static int bench__do_evlist_open_close(struct evlist *evlist)
+{
+	int err = -1;
+	char sbuf[STRERR_BUFSIZE];
+
+	err = evlist__open(evlist);
+	if (err < 0) {
+		pr_err("evlist__open: %s\n",
+			 str_error_r(errno, sbuf, sizeof(sbuf)));
+		return err;
+	}
+
+	err = evlist__mmap(evlist, opts.mmap_pages);
+	if (err < 0) {
+		pr_err("evlist__mmap: %s\n",
+			 str_error_r(errno, sbuf, sizeof(sbuf)));
+		return err;
+	}
+
+	evlist__enable(evlist);
+
+	evlist__disable(evlist);
+	evlist__munmap(evlist);
+	evlist__close(evlist);
+
+	return 0;
+}
+
+static int bench_evlist_open_close__run(char *evstr)
+{
+	struct evlist *evlist;
+	struct timeval start, end, diff;
+	double time_average, time_stddev;
+	int i;
+	int err;
+	u64 runtime_us;
+	struct stats time_stats;
+
+	init_stats(&time_stats);
+
+	// used to print statistics only
+	evlist = bench__create_evlist(evstr);
+
+	printf("  Number of cpus:\t%d\n", evlist->core.cpus->nr);
+	printf("  Number of threads:\t%d\n", evlist->core.threads->nr);
+	printf("  Number of events:\t%d (%d fds)\n",
+		evlist->core.nr_entries, evlist__count_evsel_fds(evlist));
+	printf("  Number of iterations:\t%d\n", iterations);
+
+	evlist__delete(evlist);
+
+	for (i = 0; i < iterations; i++) {
+		pr_debug("Started iteration %d\n", i);
+		evlist = bench__create_evlist(evstr);
+		gettimeofday(&start, NULL);
+		err = bench__do_evlist_open_close(evlist);
+		if (err) {
+			evlist__delete(evlist);
+			return err;
+		}
+
+		gettimeofday(&end, NULL);
+		timersub(&end, &start, &diff);
+		runtime_us = diff.tv_sec * USEC_PER_SEC + diff.tv_usec;
+		update_stats(&time_stats, runtime_us);
+
+		evlist__delete(evlist);
+		pr_debug("Iteration %d took:\t%ldus\n", i, runtime_us);
+	}
+
+	time_average = avg_stats(&time_stats);
+	time_stddev = stddev_stats(&time_stats);
+	printf("  Average open-close took: %.3f usec (+- %.3f usec)\n",
+		time_average, time_stddev);
+
+	return 0;
+}
+
+static char *bench__repeat_event_string(const char *evstr, int n)
+{
+	int err, i, final_size, str_size;
+	struct strbuf buf;
+	char sbuf[STRERR_BUFSIZE];
+
+	str_size = strlen(evstr);
+	final_size = str_size * n + n;
+
+	err = strbuf_init(&buf, final_size);
+	if (err) {
+		pr_err("strbuf_init: %s\n",
+			 str_error_r(err, sbuf, sizeof(sbuf)));
+		goto out_error;
+	}
+
+	for (i = 0; i < n; i++) {
+		err = strbuf_add(&buf, evstr, str_size);
+		if (err) {
+			pr_err("strbuf_add: %s\n",
+				str_error_r(err, sbuf, sizeof(sbuf)));
+			goto out_error;
+		}
+
+		err = strbuf_addch(&buf, i == n-1 ? '\0' : ',');
+		if (err) {
+			pr_err("strbuf_addch: %s\n",
+				str_error_r(err, sbuf, sizeof(sbuf)));
+			goto out_error;
+		}
+	}
+
+	return strbuf_detach(&buf, NULL);
+
+out_error:
+	strbuf_release(&buf);
+	return NULL;
+}
+
+
+int bench_evlist_open_close(int argc, const char **argv)
+{
+	int err = 0;
+	char *evstr, errbuf[BUFSIZ];
+
+	argc = parse_options(argc, argv, options, bench_usage, 0);
+	if (argc) {
+		usage_with_options(bench_usage, options);
+		exit(EXIT_FAILURE);
+	}
+
+	err = target__validate(&opts.target);
+	if (err) {
+		target__strerror(&opts.target, err, errbuf, BUFSIZ);
+		pr_err("%s\n", errbuf);
+		goto out;
+	}
+
+	err = target__parse_uid(&opts.target);
+	if (err) {
+		target__strerror(&opts.target, err, errbuf, BUFSIZ);
+		pr_err("%s", errbuf);
+		goto out;
+	}
+
+	/* Enable ignoring missing threads when -u/-p option is defined. */
+	opts.ignore_missing_thread = opts.target.uid != UINT_MAX || opts.target.pid;
+
+	evstr = bench__repeat_event_string(event_string, nr_events);
+	if (!evstr) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	err = bench_evlist_open_close__run(evstr);
+
+	free(evstr);
+out:
+	return err;
+}

diff --git a/tools/perf/builtin-bench.c b/tools/perf/builtin-bench.c
index 62a7b7420a448517..d0895162c2ba6411 100644
--- a/tools/perf/builtin-bench.c
+++ b/tools/perf/builtin-bench.c

@@ -88,6 +88,7 @@ static struct bench internals_benchmarks[] = {
 	{ "synthesize", "Benchmark perf event synthesis",	bench_synthesize	},
 	{ "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	},
 	{ NULL,		NULL,					NULL			}
 };
 

-- 
2.31.1