root/samples/bpf/lwt_len_hist_user.c

DEFINITIONS

1. stars
2. main

   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 
  18 static 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 
  29 int 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 }