perf bench: Add kallsyms parsing

Add a benchmark for kallsyms parsing. Example output:

Running 'internals/kallsyms-parse' benchmark:
Average kallsyms__parse took: 103.971 ms (+- 0.121 ms)

Committer testing:

Test Machine: AMD Ryzen 5 3600X 6-Core Processor

[root@five ~]# perf bench internals kallsyms-parse
# Running 'internals/kallsyms-parse' benchmark:
Average kallsyms__parse took: 79.692 ms (+- 0.101 ms)
[root@five ~]# perf stat -r5 perf bench internals kallsyms-parse
# Running 'internals/kallsyms-parse' benchmark:
Average kallsyms__parse took: 80.563 ms (+- 0.079 ms)
# Running 'internals/kallsyms-parse' benchmark:
Average kallsyms__parse took: 81.046 ms (+- 0.155 ms)
# Running 'internals/kallsyms-parse' benchmark:
Average kallsyms__parse took: 80.874 ms (+- 0.104 ms)
# Running 'internals/kallsyms-parse' benchmark:
Average kallsyms__parse took: 81.173 ms (+- 0.133 ms)
# Running 'internals/kallsyms-parse' benchmark:
Average kallsyms__parse took: 81.169 ms (+- 0.074 ms)

Performance counter stats for 'perf bench internals kallsyms-parse' (5 runs):

8,093.54 msec task-clock # 0.999 CPUs utilized ( +- 0.14% )
3,165 context-switches # 0.391 K/sec ( +- 0.18% )
10 cpu-migrations # 0.001 K/sec ( +- 23.13% )
744 page-faults # 0.092 K/sec ( +- 0.21% )
34,551,564,954 cycles # 4.269 GHz ( +- 0.05% ) (83.33%)
1,160,584,308 stalled-cycles-frontend # 3.36% frontend cycles idle ( +- 1.60% ) (83.33%)
14,974,323,985 stalled-cycles-backend # 43.34% backend cycles idle ( +- 0.24% ) (83.33%)
58,712,905,705 instructions # 1.70 insn per cycle
# 0.26 stalled cycles per insn ( +- 0.01% ) (83.34%)
14,136,433,778 branches # 1746.632 M/sec ( +- 0.01% ) (83.33%)
141,943,217 branch-misses # 1.00% of all branches ( +- 0.04% ) (83.33%)

8.1040 +- 0.0115 seconds time elapsed ( +- 0.14% )

[root@five ~]#

Signed-off-by: Ian Rogers <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/bench/Build

···
 perf-y += epoll-wait.o
 perf-y += epoll-ctl.o
 perf-y += synthesize.o
+perf-y += kallsyms-parse.o
 
 perf-$(CONFIG_X86_64) += mem-memcpy-x86-64-lib.o
 perf-$(CONFIG_X86_64) += mem-memcpy-x86-64-asm.o

tools/perf/bench/bench.h

···
 int bench_epoll_wait(int argc, const char **argv);
 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);
 
 #define BENCH_FORMAT_DEFAULT_STR	"default"
 #define BENCH_FORMAT_DEFAULT		0

tools/perf/bench/kallsyms-parse.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Benchmark of /proc/kallsyms parsing.
+ *
+ * Copyright 2020 Google LLC.
+ */
+#include <stdlib.h>
+#include "bench.h"
+#include "../util/stat.h"
+#include <linux/time64.h>
+#include <subcmd/parse-options.h>
+#include <symbol/kallsyms.h>
+
+static unsigned int iterations = 100;
+
+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 kallsyms-parse <options>",
+	NULL
+};
+
+static int bench_process_symbol(void *arg __maybe_unused,
+				const char *name __maybe_unused,
+				char type __maybe_unused,
+				u64 start __maybe_unused)
+{
+	return 0;
+}
+
+static int do_kallsyms_parse(void)
+{
+	struct timeval start, end, diff;
+	u64 runtime_us;
+	unsigned int i;
+	double time_average, time_stddev;
+	int err;
+	struct stats time_stats;
+
+	init_stats(&time_stats);
+
+	for (i = 0; i < iterations; i++) {
+		gettimeofday(&start, NULL);
+		err = kallsyms__parse("/proc/kallsyms", NULL,
+				bench_process_symbol);
+		if (err)
+			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);
+	}
+
+	time_average = avg_stats(&time_stats) / USEC_PER_MSEC;
+	time_stddev = stddev_stats(&time_stats) / USEC_PER_MSEC;
+	printf("  Average kallsyms__parse took: %.3f ms (+- %.3f ms)\n",
+		time_average, time_stddev);
+	return 0;
+}
+
+int bench_kallsyms_parse(int argc, const char **argv)
+{
+	argc = parse_options(argc, argv, options, bench_usage, 0);
+	if (argc) {
+		usage_with_options(bench_usage, options);
+		exit(EXIT_FAILURE);
+	}
+
+	return do_kallsyms_parse();
+}

tools/perf/builtin-bench.c

···
 
 static struct bench internals_benchmarks[] = {
 	{ "synthesize", "Benchmark perf event synthesis",	bench_synthesize	},
+	{ "kallsyms-parse", "Benchmark kallsyms parsing",	bench_kallsyms_parse	},
 	{ NULL,		NULL,					NULL			}
 };