1#include <linux/unistd.h>
 2#include <linux/bpf.h>
 3
 4#include <stdlib.h>
 5#include <stdio.h>
 6#include <unistd.h>
 7#include <string.h>
 8#include <errno.h>
 9#include <arpa/inet.h>
10
11#include "libbpf.h"
12#include "bpf_util.h"
13
14#define MAX_INDEX 64
15#define MAX_STARS 38
16
17char bpf_log_buf[BPF_LOG_BUF_SIZE];
18
19static void stars(char *str, long val, long max, int width)
20{
21	int i;
22
23	for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
24		str[i] = '*';
25	if (val > max)
26		str[i - 1] = '+';
27	str[i] = '\0';
28}
29
30int main(int argc, char **argv)
31{
32	unsigned int nr_cpus = bpf_num_possible_cpus();
33	const char *map_filename = "/sys/fs/bpf/tc/globals/lwt_len_hist_map";
34	uint64_t values[nr_cpus], sum, max_value = 0, data[MAX_INDEX] = {};
35	uint64_t key = 0, next_key, max_key = 0;
36	char starstr[MAX_STARS];
37	int i, map_fd;
38
39	map_fd = bpf_obj_get(map_filename);
40	if (map_fd < 0) {
41		fprintf(stderr, "bpf_obj_get(%s): %s(%d)\n",
42			map_filename, strerror(errno), errno);
43		return -1;
44	}
45
46	while (bpf_map_get_next_key(map_fd, &key, &next_key) == 0) {
47		if (next_key >= MAX_INDEX) {
48			fprintf(stderr, "Key %lu out of bounds\n", next_key);
49			continue;
50		}
51
52		bpf_map_lookup_elem(map_fd, &next_key, values);
53
54		sum = 0;
55		for (i = 0; i < nr_cpus; i++)
56			sum += values[i];
57
58		data[next_key] = sum;
59		if (sum && next_key > max_key)
60			max_key = next_key;
61
62		if (sum > max_value)
63			max_value = sum;
64
65		key = next_key;
66	}
67
68	for (i = 1; i <= max_key + 1; i++) {
69		stars(starstr, data[i - 1], max_value, MAX_STARS);
70		printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
71		       (1l << i) >> 1, (1l << i) - 1, data[i - 1],
72		       MAX_STARS, starstr);
73	}
74
75	close(map_fd);
76
77	return 0;
78}