12 static void stars(char *str, long val, long max, int width)
16 for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
23 static void print_hist(int fd)
27 long data[MAX_INDEX] = {};
28 char starstr[MAX_STARS];
33 for (key = 0; key < MAX_INDEX; key++) {
34 bpf_lookup_elem(fd, &key, &value);
36 if (value && key > max_ind)
38 if (value > max_value)
42 printf(" syscall write() stats\n");
43 printf(" byte_size : count distribution\n");
44 for (i = 1; i <= max_ind + 1; i++) {
45 stars(starstr, data[i - 1], max_value, MAX_STARS);
46 printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
47 (1l << i) >> 1, (1l << i) - 1, data[i - 1],
51 static void int_exit(int sig)
53 print_hist(map_fd[1]);
57 int main(int ac, char **argv)
60 long key, next_key, value;
64 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
66 signal(SIGINT, int_exit);
68 /* start 'ping' in the background to have some kfree_skb events */
69 f = popen("ping -c5 localhost", "r");
72 /* start 'dd' in the background to have plenty of 'write' syscalls */
73 f = popen("dd if=/dev/zero of=/dev/null count=5000000", "r");
76 if (load_bpf_file(filename)) {
77 printf("%s", bpf_log_buf);
81 for (i = 0; i < 5; i++) {
83 while (bpf_get_next_key(map_fd[0], &key, &next_key) == 0) {
84 bpf_lookup_elem(map_fd[0], &next_key, &value);
85 printf("location 0x%lx count %ld\n", next_key, value);
92 print_hist(map_fd[1]);