1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Benchmark scanning sysfs files for PMU information.
4 *
5 * Copyright 2023 Google LLC.
6 */
7#include <stdio.h>
8#include "bench.h"
9#include "util/debug.h"
10#include "util/pmu.h"
11#include "util/pmus.h"
12#include "util/stat.h"
13#include <linux/atomic.h>
14#include <linux/err.h>
15#include <linux/time64.h>
16#include <subcmd/parse-options.h>
17
18static unsigned int iterations = 100;
19
20struct pmu_scan_result {
21	char *name;
22	int nr_aliases;
23	int nr_formats;
24	int nr_caps;
25	bool is_core;
26};
27
28static const struct option options[] = {
29	OPT_UINTEGER('i', "iterations", &iterations,
30		"Number of iterations used to compute average"),
31	OPT_END()
32};
33
34static const char *const bench_usage[] = {
35	"perf bench internals pmu-scan <options>",
36	NULL
37};
38
39static int nr_pmus;
40static struct pmu_scan_result *results;
41
42static int save_result(void)
43{
44	struct perf_pmu *pmu = NULL;
45	struct list_head *list;
46	struct pmu_scan_result *r;
47
48	while ((pmu = perf_pmus__scan(pmu)) != NULL) {
49		r = realloc(results, (nr_pmus + 1) * sizeof(*r));
50		if (r == NULL)
51			return -ENOMEM;
52
53		results = r;
54		r = results + nr_pmus;
55
56		r->name = strdup(pmu->name);
57		r->is_core = pmu->is_core;
58		r->nr_caps = pmu->nr_caps;
59
60		r->nr_aliases = perf_pmu__num_events(pmu);
61
62		r->nr_formats = 0;
63		list_for_each(list, &pmu->format)
64			r->nr_formats++;
65
66		pr_debug("pmu[%d] name=%s, nr_caps=%d, nr_aliases=%d, nr_formats=%d\n",
67			nr_pmus, r->name, r->nr_caps, r->nr_aliases, r->nr_formats);
68		nr_pmus++;
69	}
70
71	perf_pmus__destroy();
72	return 0;
73}
74
75static int check_result(bool core_only)
76{
77	struct pmu_scan_result *r;
78	struct perf_pmu *pmu;
79	struct list_head *list;
80	int nr;
81
82	for (int i = 0; i < nr_pmus; i++) {
83		r = &results[i];
84		if (core_only && !r->is_core)
85			continue;
86
87		pmu = perf_pmus__find(r->name);
88		if (pmu == NULL) {
89			pr_err("Cannot find PMU %s\n", r->name);
90			return -1;
91		}
92
93		if (pmu->nr_caps != (u32)r->nr_caps) {
94			pr_err("Unmatched number of event caps in %s: expect %d vs got %d\n",
95				pmu->name, r->nr_caps, pmu->nr_caps);
96			return -1;
97		}
98
99		nr = perf_pmu__num_events(pmu);
100		if (nr != r->nr_aliases) {
101			pr_err("Unmatched number of event aliases in %s: expect %d vs got %d\n",
102				pmu->name, r->nr_aliases, nr);
103			return -1;
104		}
105
106		nr = 0;
107		list_for_each(list, &pmu->format)
108			nr++;
109		if (nr != r->nr_formats) {
110			pr_err("Unmatched number of event formats in %s: expect %d vs got %d\n",
111				pmu->name, r->nr_formats, nr);
112			return -1;
113		}
114	}
115	return 0;
116}
117
118static void delete_result(void)
119{
120	for (int i = 0; i < nr_pmus; i++)
121		free(results[i].name);
122	free(results);
123
124	results = NULL;
125	nr_pmus = 0;
126}
127
128static int run_pmu_scan(void)
129{
130	struct stats stats;
131	struct timeval start, end, diff;
132	double time_average, time_stddev;
133	u64 runtime_us;
134	int ret;
135
136	init_stats(&stats);
137	pr_info("Computing performance of sysfs PMU event scan for %u times\n",
138		iterations);
139
140	if (save_result() < 0) {
141		pr_err("Failed to initialize PMU scan result\n");
142		return -1;
143	}
144
145	for (int j = 0; j < 2; j++) {
146		bool core_only = (j == 0);
147
148		for (unsigned int i = 0; i < iterations; i++) {
149			gettimeofday(&start, NULL);
150			if (core_only)
151				perf_pmus__scan_core(NULL);
152			else
153				perf_pmus__scan(NULL);
154			gettimeofday(&end, NULL);
155			timersub(&end, &start, &diff);
156			runtime_us = diff.tv_sec * USEC_PER_SEC + diff.tv_usec;
157			update_stats(&stats, runtime_us);
158
159			ret = check_result(core_only);
160			perf_pmus__destroy();
161			if (ret < 0)
162				break;
163		}
164		time_average = avg_stats(&stats);
165		time_stddev = stddev_stats(&stats);
166		pr_info("  Average%s PMU scanning took: %.3f usec (+- %.3f usec)\n",
167			core_only ? " core" : "", time_average, time_stddev);
168	}
169	delete_result();
170	return 0;
171}
172
173int bench_pmu_scan(int argc, const char **argv)
174{
175	int err = 0;
176
177	argc = parse_options(argc, argv, options, bench_usage, 0);
178	if (argc) {
179		usage_with_options(bench_usage, options);
180		exit(EXIT_FAILURE);
181	}
182
183	err = run_pmu_scan();
184
185	return err;
186}
187