samples/bpf/lathist_user.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
   3  * Copyright (c) 2015 BMW Car IT GmbH
   4  */
   5 #include <stdio.h>
   6 #include <unistd.h>
   7 #include <stdlib.h>
   8 #include <signal.h>
   9 #include <linux/bpf.h>
  10 #include <bpf/bpf.h>
  11 #include "bpf_load.h"
  12
  13 #define MAX_ENTRIES     20
  14 #define MAX_CPU         4
  15 #define MAX_STARS       40
  16
  17 struct cpu_hist {
  18         long data[MAX_ENTRIES];
  19         long max;
  20 };
  21
  22 static struct cpu_hist cpu_hist[MAX_CPU];
  23
  24 static void stars(char *str, long val, long max, int width)
  25 {
  26         int i;
  27
  28         for (i = 0; i < (width * val / max) - 1 && i < width - 1; i++)
  29                 str[i] = '*';
  30         if (val > max)
  31                 str[i - 1] = '+';
  32         str[i] = '\0';
  33 }
  34
  35 static void print_hist(void)
  36 {
  37         char starstr[MAX_STARS];
  38         struct cpu_hist *hist;
  39         int i, j;
  40
  41         /* clear screen */
  42         printf("\033[2J");
  43
  44         for (j = 0; j < MAX_CPU; j++) {
  45                 hist = &cpu_hist[j];
  46
  47                 /* ignore CPUs without data (maybe offline?) */
  48                 if (hist->max == 0)
  49                         continue;
  50
  51                 printf("CPU %d\n", j);
  52                 printf("      latency        : count     distribution\n");
  53                 for (i = 1; i <= MAX_ENTRIES; i++) {
  54                         stars(starstr, hist->data[i - 1], hist->max, MAX_STARS);
  55                         printf("%8ld -> %-8ld : %-8ld |%-*s|\n",
  56                                 (1l << i) >> 1, (1l << i) - 1,
  57                                 hist->data[i - 1], MAX_STARS, starstr);
  58                 }
  59         }
  60 }
  61
  62 static void get_data(int fd)
  63 {
  64         long key, value;
  65         int c, i;
  66
  67         for (i = 0; i < MAX_CPU; i++)
  68                 cpu_hist[i].max = 0;
  69
  70         for (c = 0; c < MAX_CPU; c++) {
  71                 for (i = 0; i < MAX_ENTRIES; i++) {
  72                         key = c * MAX_ENTRIES + i;
  73                         bpf_map_lookup_elem(fd, &key, &value);
  74
  75                         cpu_hist[c].data[i] = value;
  76                         if (value > cpu_hist[c].max)
  77                                 cpu_hist[c].max = value;
  78                 }
  79         }
  80 }
  81
  82 int main(int argc, char **argv)
  83 {
  84         char filename[256];
  85
  86         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  87
  88         if (load_bpf_file(filename)) {
  89                 printf("%s", bpf_log_buf);
  90                 return 1;
  91         }
  92
  93         while (1) {
  94                 get_data(map_fd[1]);
  95                 print_hist();
  96                 sleep(5);
  97         }
  98
  99         return 0;
 100 }