samples/bpf/test_overhead_user.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2016 Facebook
   3  */
   4 #define _GNU_SOURCE
   5 #include <sched.h>
   6 #include <errno.h>
   7 #include <stdio.h>
   8 #include <sys/types.h>
   9 #include <asm/unistd.h>
  10 #include <fcntl.h>
  11 #include <unistd.h>
  12 #include <assert.h>
  13 #include <sys/wait.h>
  14 #include <stdlib.h>
  15 #include <signal.h>
  16 #include <linux/bpf.h>
  17 #include <string.h>
  18 #include <time.h>
  19 #include <sys/resource.h>
  20 #include <bpf/bpf.h>
  21 #include <bpf/libbpf.h>
  22
  23 #define MAX_CNT 1000000
  24
  25 static struct bpf_link *links[2];
  26 static struct bpf_object *obj;
  27 static int cnt;
  28
  29 static __u64 time_get_ns(void)
  30 {
  31         struct timespec ts;
  32
  33         clock_gettime(CLOCK_MONOTONIC, &ts);
  34         return ts.tv_sec * 1000000000ull + ts.tv_nsec;
  35 }
  36
  37 static void test_task_rename(int cpu)
  38 {
  39         __u64 start_time;
  40         char buf[] = "test\n";
  41         int i, fd;
  42
  43         fd = open("/proc/self/comm", O_WRONLY|O_TRUNC);
  44         if (fd < 0) {
  45                 printf("couldn't open /proc\n");
  46                 exit(1);
  47         }
  48         start_time = time_get_ns();
  49         for (i = 0; i < MAX_CNT; i++) {
  50                 if (write(fd, buf, sizeof(buf)) < 0) {
  51                         printf("task rename failed: %s\n", strerror(errno));
  52                         close(fd);
  53                         return;
  54                 }
  55         }
  56         printf("task_rename:%d: %lld events per sec\n",
  57                cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
  58         close(fd);
  59 }
  60
  61 static void test_urandom_read(int cpu)
  62 {
  63         __u64 start_time;
  64         char buf[4];
  65         int i, fd;
  66
  67         fd = open("/dev/urandom", O_RDONLY);
  68         if (fd < 0) {
  69                 printf("couldn't open /dev/urandom\n");
  70                 exit(1);
  71         }
  72         start_time = time_get_ns();
  73         for (i = 0; i < MAX_CNT; i++) {
  74                 if (read(fd, buf, sizeof(buf)) < 0) {
  75                         printf("failed to read from /dev/urandom: %s\n", strerror(errno));
  76                         close(fd);
  77                         return;
  78                 }
  79         }
  80         printf("urandom_read:%d: %lld events per sec\n",
  81                cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
  82         close(fd);
  83 }
  84
  85 static void loop(int cpu, int flags)
  86 {
  87         cpu_set_t cpuset;
  88
  89         CPU_ZERO(&cpuset);
  90         CPU_SET(cpu, &cpuset);
  91         sched_setaffinity(0, sizeof(cpuset), &cpuset);
  92
  93         if (flags & 1)
  94                 test_task_rename(cpu);
  95         if (flags & 2)
  96                 test_urandom_read(cpu);
  97 }
  98
  99 static void run_perf_test(int tasks, int flags)
 100 {
 101         pid_t pid[tasks];
 102         int i;
 103
 104         for (i = 0; i < tasks; i++) {
 105                 pid[i] = fork();
 106                 if (pid[i] == 0) {
 107                         loop(i, flags);
 108                         exit(0);
 109                 } else if (pid[i] == -1) {
 110                         printf("couldn't spawn #%d process\n", i);
 111                         exit(1);
 112                 }
 113         }
 114         for (i = 0; i < tasks; i++) {
 115                 int status;
 116
 117                 assert(waitpid(pid[i], &status, 0) == pid[i]);
 118                 assert(status == 0);
 119         }
 120 }
 121
 122 static int load_progs(char *filename)
 123 {
 124         struct bpf_program *prog;
 125         int err = 0;
 126
 127         obj = bpf_object__open_file(filename, NULL);
 128         err = libbpf_get_error(obj);
 129         if (err < 0) {
 130                 fprintf(stderr, "ERROR: opening BPF object file failed\n");
 131                 return err;
 132         }
 133
 134         /* load BPF program */
 135         err = bpf_object__load(obj);
 136         if (err < 0) {
 137                 fprintf(stderr, "ERROR: loading BPF object file failed\n");
 138                 return err;
 139         }
 140
 141         bpf_object__for_each_program(prog, obj) {
 142                 links[cnt] = bpf_program__attach(prog);
 143                 err = libbpf_get_error(links[cnt]);
 144                 if (err < 0) {
 145                         fprintf(stderr, "ERROR: bpf_program__attach failed\n");
 146                         links[cnt] = NULL;
 147                         return err;
 148                 }
 149                 cnt++;
 150         }
 151
 152         return err;
 153 }
 154
 155 static void unload_progs(void)
 156 {
 157         while (cnt)
 158                 bpf_link__destroy(links[--cnt]);
 159
 160         bpf_object__close(obj);
 161 }
 162
 163 int main(int argc, char **argv)
 164 {
 165         int num_cpu = sysconf(_SC_NPROCESSORS_ONLN);
 166         int test_flags = ~0;
 167         char filename[256];
 168         int err = 0;
 169
 170
 171         if (argc > 1)
 172                 test_flags = atoi(argv[1]) ? : test_flags;
 173         if (argc > 2)
 174                 num_cpu = atoi(argv[2]) ? : num_cpu;
 175
 176         if (test_flags & 0x3) {
 177                 printf("BASE\n");
 178                 run_perf_test(num_cpu, test_flags);
 179         }
 180
 181         if (test_flags & 0xC) {
 182                 snprintf(filename, sizeof(filename),
 183                          "%s_kprobe_kern.o", argv[0]);
 184
 185                 printf("w/KPROBE\n");
 186                 err = load_progs(filename);
 187                 if (!err)
 188                         run_perf_test(num_cpu, test_flags >> 2);
 189
 190                 unload_progs();
 191         }
 192
 193         if (test_flags & 0x30) {
 194                 snprintf(filename, sizeof(filename),
 195                          "%s_tp_kern.o", argv[0]);
 196                 printf("w/TRACEPOINT\n");
 197                 err = load_progs(filename);
 198                 if (!err)
 199                         run_perf_test(num_cpu, test_flags >> 4);
 200
 201                 unload_progs();
 202         }
 203
 204         if (test_flags & 0xC0) {
 205                 snprintf(filename, sizeof(filename),
 206                          "%s_raw_tp_kern.o", argv[0]);
 207                 printf("w/RAW_TRACEPOINT\n");
 208                 err = load_progs(filename);
 209                 if (!err)
 210                         run_perf_test(num_cpu, test_flags >> 6);
 211
 212                 unload_progs();
 213         }
 214
 215         return err;
 216 }