samples/bpf/lathist_user.c

   1 /* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
   2  * Copyright (c) 2015 BMW Car IT GmbH
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of version 2 of the GNU General Public
   6  * License as published by the Free Software Foundation.
   7  */
   8 #include <stdio.h>
   9 #include <unistd.h>
  10 #include <stdlib.h>
  11 #include <signal.h>
  12 #include <linux/bpf.h>
  13 #include "libbpf.h"
  14 #include "bpf_load.h"
  15
  16 #define MAX_ENTRIES     20
  17 #define MAX_CPU         4
  18 #define MAX_STARS       40
  19
  20 struct cpu_hist {
  21         long data[MAX_ENTRIES];
  22         long max;
  23 };
  24
  25 static struct cpu_hist cpu_hist[MAX_CPU];
  26
  27 static void stars(char *str, long val, long max, int width)
  28 {
  29         int i;
  30
  31         for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
  32                 str[i] = '*';
  33         if (val > max)
  34                 str[i - 1] = '+';
  35         str[i] = '\0';
  36 }
  37
  38 static void print_hist(void)
  39 {
  40         char starstr[MAX_STARS];
  41         struct cpu_hist *hist;
  42         int i, j;
  43
  44         /* clear screen */
  45         printf("\033[2J");
  46
  47         for (j = 0; j < MAX_CPU; j++) {
  48                 hist = &cpu_hist[j];
  49
  50                 /* ignore CPUs without data (maybe offline?) */
  51                 if (hist->max == 0)
  52                         continue;
  53
  54                 printf("CPU %d\n", j);
  55                 printf("      latency        : count     distribution\n");
  56                 for (i = 1; i <= MAX_ENTRIES; i++) {
  57                         stars(starstr, hist->data[i - 1], hist->max, MAX_STARS);
  58                         printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
  59                                 (1l << i) >> 1, (1l << i) - 1,
  60                                 hist->data[i - 1], MAX_STARS, starstr);
  61                 }
  62         }
  63 }
  64
  65 static void get_data(int fd)
  66 {
  67         long key, value;
  68         int c, i;
  69
  70         for (i = 0; i < MAX_CPU; i++)
  71                 cpu_hist[i].max = 0;
  72
  73         for (c = 0; c < MAX_CPU; c++) {
  74                 for (i = 0; i < MAX_ENTRIES; i++) {
  75                         key = c * MAX_ENTRIES + i;
  76                         bpf_map_lookup_elem(fd, &key, &value);
  77
  78                         cpu_hist[c].data[i] = value;
  79                         if (value > cpu_hist[c].max)
  80                                 cpu_hist[c].max = value;
  81                 }
  82         }
  83 }
  84
  85 int main(int argc, char **argv)
  86 {
  87         char filename[256];
  88
  89         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  90
  91         if (load_bpf_file(filename)) {
  92                 printf("%s", bpf_log_buf);
  93                 return 1;
  94         }
  95
  96         while (1) {
  97                 get_data(map_fd[1]);
  98                 print_hist();
  99                 sleep(5);
 100         }
 101
 102         return 0;
 103 }