LXR linux/samples/bpf/lwt_len_hist

   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
  17char bpf_log_buf[BPF_LOG_BUF_SIZE];
  18
  19static 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
  30int 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}
  79