samples/bpf/lwt_len_hist_user.c

   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
  17 char bpf_log_buf[BPF_LOG_BUF_SIZE];
  18
  19 static 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
  30 int 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 }