1/*
2 *
3 * syscall.c
4 *
5 * syscall: Benchmark for system call performance
6 */
7#include "../perf.h"
8#include "../util/util.h"
9#include <subcmd/parse-options.h>
10#include "../builtin.h"
11#include "bench.h"
12
13#include <stdio.h>
14#include <sys/time.h>
15#include <sys/syscall.h>
16#include <sys/types.h>
17#include <sys/wait.h>
18#include <unistd.h>
19#include <stdlib.h>
20
21#ifndef __NR_fork
22#define __NR_fork -1
23#endif
24
25static int loops;
26
27static const struct option options[] = {
28 OPT_INTEGER('l', "loop", &loops, "Specify number of loops"),
29 OPT_END()
30};
31
32static const char * const bench_syscall_usage[] = {
33 "perf bench syscall <options>",
34 NULL
35};
36
37static void test_fork(void)
38{
39 pid_t pid = fork();
40
41 if (pid < 0) {
42 fprintf(stderr, "fork failed\n");
43 exit(1);
44 } else if (pid == 0) {
45 exit(0);
46 } else {
47 if (waitpid(pid, NULL, 0) < 0) {
48 fprintf(stderr, "waitpid failed\n");
49 exit(1);
50 }
51 }
52}
53
54static void test_execve(void)
55{
56 const char *pathname = "/bin/true";
57 char *const argv[] = { (char *)pathname, NULL };
58 pid_t pid = fork();
59
60 if (pid < 0) {
61 fprintf(stderr, "fork failed\n");
62 exit(1);
63 } else if (pid == 0) {
64 execve(pathname, argv, NULL);
65 fprintf(stderr, "execve /bin/true failed\n");
66 exit(1);
67 } else {
68 if (waitpid(pid, NULL, 0) < 0) {
69 fprintf(stderr, "waitpid failed\n");
70 exit(1);
71 }
72 }
73}
74
75static int bench_syscall_common(int argc, const char **argv, int syscall)
76{
77 struct timeval start, stop, diff;
78 unsigned long long result_usec = 0;
79 const char *name = NULL;
80 int i;
81
82 switch (syscall) {
83 case __NR_fork:
84 case __NR_execve:
85 /* Limit default loop to 10000 times to save time */
86 loops = 10000;
87 break;
88 default:
89 loops = 10000000;
90 break;
91 }
92
93 /* Options -l and --loops override default above */
94 argc = parse_options(argc, argv, options, bench_syscall_usage, 0);
95
96 gettimeofday(&start, NULL);
97
98 for (i = 0; i < loops; i++) {
99 switch (syscall) {
100 case __NR_getppid:
101 getppid();
102 break;
103 case __NR_getpgid:
104 getpgid(0);
105 break;
106 case __NR_fork:
107 test_fork();
108 break;
109 case __NR_execve:
110 test_execve();
111 default:
112 break;
113 }
114 }
115
116 gettimeofday(&stop, NULL);
117 timersub(&stop, &start, &diff);
118
119 switch (syscall) {
120 case __NR_getppid:
121 name = "getppid()";
122 break;
123 case __NR_getpgid:
124 name = "getpgid()";
125 break;
126 case __NR_fork:
127 name = "fork()";
128 break;
129 case __NR_execve:
130 name = "execve()";
131 break;
132 default:
133 break;
134 }
135
136 switch (bench_format) {
137 case BENCH_FORMAT_DEFAULT:
138 printf("# Executed %'d %s calls\n", loops, name);
139
140 result_usec = diff.tv_sec * 1000000;
141 result_usec += diff.tv_usec;
142
143 printf(" %14s: %lu.%03lu [sec]\n\n", "Total time",
144 (unsigned long) diff.tv_sec,
145 (unsigned long) (diff.tv_usec/1000));
146
147 printf(" %14lf usecs/op\n",
148 (double)result_usec / (double)loops);
149 printf(" %'14d ops/sec\n",
150 (int)((double)loops /
151 ((double)result_usec / (double)1000000)));
152 break;
153
154 case BENCH_FORMAT_SIMPLE:
155 printf("%lu.%03lu\n",
156 (unsigned long) diff.tv_sec,
157 (unsigned long) (diff.tv_usec / 1000));
158 break;
159
160 default:
161 /* reaching here is something disaster */
162 fprintf(stderr, "Unknown format:%d\n", bench_format);
163 exit(1);
164 break;
165 }
166
167 return 0;
168}
169
170int bench_syscall_basic(int argc, const char **argv)
171{
172 return bench_syscall_common(argc, argv, syscall: __NR_getppid);
173}
174
175int bench_syscall_getpgid(int argc, const char **argv)
176{
177 return bench_syscall_common(argc, argv, syscall: __NR_getpgid);
178}
179
180int bench_syscall_fork(int argc, const char **argv)
181{
182 return bench_syscall_common(argc, argv, __NR_fork);
183}
184
185int bench_syscall_execve(int argc, const char **argv)
186{
187 return bench_syscall_common(argc, argv, syscall: __NR_execve);
188}
189

source code of linux/tools/perf/bench/syscall.c