samples/bpf/lwt_len_hist_user.c

   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 "libbpf.h"
  13 #include "bpf_util.h"
  14
  15 #define MAX_INDEX 64
  16 #define MAX_STARS 38
  17
  18 char bpf_log_buf[BPF_LOG_BUF_SIZE];
  19
  20 static 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
  31 int 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 }