LXR linux/samples/bpf/lathist

   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
  20struct cpu_hist {
  21        long data[MAX_ENTRIES];
  22        long max;
  23};
  24
  25static struct cpu_hist cpu_hist[MAX_CPU];
  26
  27static 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
  38static 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
  65static 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_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
  85int 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}
 104