1// SPDX-License-Identifier: GPL-2.0
2#include <linux/unistd.h>
3#include <linux/bpf.h>
4
5#include <stdlib.h>
6#include <stdio.h>
7#include <unistd.h>
8#include <string.h>
9#include <errno.h>
10#include <arpa/inet.h>
11
12#include <bpf/bpf.h>
13#include "bpf_util.h"
14
15#define MAX_INDEX 64
16#define MAX_STARS 38
17
18static void stars(char *str, long val, long max, int width)
19{
20	int i;
21
22	for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
23		str[i] = '*';
24	if (val > max)
25		str[i - 1] = '+';
26	str[i] = '\0';
27}
28
29int main(int argc, char **argv)
30{
31	unsigned int nr_cpus = bpf_num_possible_cpus();
32	const char *map_filename = "/sys/fs/bpf/tc/globals/lwt_len_hist_map";
33	uint64_t values[nr_cpus], sum, max_value = 0, data[MAX_INDEX] = {};
34	uint64_t key = 0, next_key, max_key = 0;
35	char starstr[MAX_STARS];
36	int i, map_fd;
37
38	map_fd = bpf_obj_get(map_filename);
39	if (map_fd < 0) {
40		fprintf(stderr, "bpf_obj_get(%s): %s(%d)\n",
41			map_filename, strerror(errno), errno);
42		return -1;
43	}
44
45	while (bpf_map_get_next_key(map_fd, &key, &next_key) == 0) {
46		if (next_key >= MAX_INDEX) {
47			fprintf(stderr, "Key %lu out of bounds\n", next_key);
48			continue;
49		}
50
51		bpf_map_lookup_elem(map_fd, &next_key, values);
52
53		sum = 0;
54		for (i = 0; i < nr_cpus; i++)
55			sum += values[i];
56
57		data[next_key] = sum;
58		if (sum && next_key > max_key)
59			max_key = next_key;
60
61		if (sum > max_value)
62			max_value = sum;
63
64		key = next_key;
65	}
66
67	for (i = 1; i <= max_key + 1; i++) {
68		stars(starstr, data[i - 1], max_value, MAX_STARS);
69		printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
70		       (1l << i) >> 1, (1l << i) - 1, data[i - 1],
71		       MAX_STARS, starstr);
72	}
73
74	close(map_fd);
75
76	return 0;
77}
78