1#include <stdio.h>
2#include <unistd.h>
3#include <stdlib.h>
4#include <signal.h>
5#include <linux/bpf.h>
6#include "libbpf.h"
7#include "bpf_load.h"
8
9#define MAX_INDEX	64
10#define MAX_STARS	38
11
12static void stars(char *str, long val, long max, int width)
13{
14	int i;
15
16	for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
17		str[i] = '*';
18	if (val > max)
19		str[i - 1] = '+';
20	str[i] = '\0';
21}
22
23static void print_hist(int fd)
24{
25	int key;
26	long value;
27	long data[MAX_INDEX] = {};
28	char starstr[MAX_STARS];
29	int i;
30	int max_ind = -1;
31	long max_value = 0;
32
33	for (key = 0; key < MAX_INDEX; key++) {
34		bpf_lookup_elem(fd, &key, &value);
35		data[key] = value;
36		if (value && key > max_ind)
37			max_ind = key;
38		if (value > max_value)
39			max_value = value;
40	}
41
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],
48		       MAX_STARS, starstr);
49	}
50}
51static void int_exit(int sig)
52{
53	print_hist(map_fd[1]);
54	exit(0);
55}
56
57int main(int ac, char **argv)
58{
59	char filename[256];
60	long key, next_key, value;
61	FILE *f;
62	int i;
63
64	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
65
66	signal(SIGINT, int_exit);
67
68	/* start 'ping' in the background to have some kfree_skb events */
69	f = popen("ping -c5 localhost", "r");
70	(void) f;
71
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");
74	(void) f;
75
76	if (load_bpf_file(filename)) {
77		printf("%s", bpf_log_buf);
78		return 1;
79	}
80
81	for (i = 0; i < 5; i++) {
82		key = 0;
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);
86			key = next_key;
87		}
88		if (key)
89			printf("\n");
90		sleep(1);
91	}
92	print_hist(map_fd[1]);
93
94	return 0;
95}
96