#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>


/* Meta Information */

MODULE_LICENSE("GPL");

// declare variables
static unsigned int i = 0;
static char ** buffer;
static int loop_cnt;
static int alloc_size;

// declare module parameters
module_param(loop_cnt, int, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
module_param(alloc_size, int, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);

static int __init initmodule(void) {
  // get size of void pointer later returned by kmalloc(...)
  int size = sizeof(void*);
  /*
    init buffer array for loop_cnt elements with size of void*
    |-|-|-|
  */
  buffer = kmalloc_array(loop_cnt, size, GFP_KERNEL);

  printk(KERN_DEBUG "Allocating %d times the memory size of %d\n", loop_cnt, alloc_size);

  // stop total time
  long long totalStart;
  long long totalStop;
  totalStart = rdtsc();
  
  // allocate loop_ctn times the memory of size alloc_size
  while (i < loop_cnt) {
    long long start;
    long long stop;

    start = rdtsc();
    // allocate size of alloc_size and assign void* to buffer[i]
    buffer[i] = kmalloc(alloc_size, GFP_KERNEL);
    stop = rdtsc();

    printk(KERN_DEBUG "%i: It took %lld ticks to allocate the memory\n", i, stop - start);
    i++;
  }

  totalStop = rdtsc();

  printk(KERN_DEBUG "Total:  It took %lld ticks to allocate the memory\n", totalStop - totalStart);
  return 0;
}

static void __exit moduleExit(void) {

  while (i > 0) {
    kfree(buffer[i]);
    printk(KERN_DEBUG "Cleared\n");
    i--;
  }
}

module_init(initmodule);
module_exit(moduleExit);