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
18char bpf_log_buf[BPF_LOG_BUF_SIZE];
19
20static void stars(char *str, long val, long max, int width)
21{
22	int i;
23
24	for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
25		str[i] = '*';
26	if (val > max)
27		str[i - 1] = '+';
28	str[i] = '\0';
29}
30
31int main(int argc, char **argv)
32{
33	unsigned int nr_cpus = bpf_num_possible_cpus();
34	const char *map_filename = "/sys/fs/bpf/tc/globals/lwt_len_hist_map";
35	uint64_t values[nr_cpus], sum, max_value = 0, data[MAX_INDEX] = {};
36	uint64_t key = 0, next_key, max_key = 0;
37	char starstr[MAX_STARS];
38	int i, map_fd;
39
40	map_fd = bpf_obj_get(map_filename);
41	if (map_fd < 0) {
42		fprintf(stderr, "bpf_obj_get(%s): %s(%d)\n",
43			map_filename, strerror(errno), errno);
44		return -1;
45	}
46
47	while (bpf_map_get_next_key(map_fd, &key, &next_key) == 0) {
48		if (next_key >= MAX_INDEX) {
49			fprintf(stderr, "Key %lu out of bounds\n", next_key);
50			continue;
51		}
52
53		bpf_map_lookup_elem(map_fd, &next_key, values);
54
55		sum = 0;
56		for (i = 0; i < nr_cpus; i++)
57			sum += values[i];
58
59		data[next_key] = sum;
60		if (sum && next_key > max_key)
61			max_key = next_key;
62
63		if (sum > max_value)
64			max_value = sum;
65
66		key = next_key;
67	}
68
69	for (i = 1; i <= max_key + 1; i++) {
70		stars(starstr, data[i - 1], max_value, MAX_STARS);
71		printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
72		       (1l << i) >> 1, (1l << i) - 1, data[i - 1],
73		       MAX_STARS, starstr);
74	}
75
76	close(map_fd);
77
78	return 0;
79}