#include <linux/init.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>

MODULE_LICENSE("GPL");

#define N 30000
#define MAX 20000

extern unsigned foo(void);

static int hello_init(void)
{
  int i;
  int *lat;
  printk(KERN_ALERT "INIT\n");
  lat = kmalloc(MAX * sizeof *lat, GFP_KERNEL);
  if (lat == NULL) return -1;
  for (i=0; i < MAX; ++i) lat[i] = 0;
  for (i=0; i < 5; ++i) foo();
  for (i=0; i < N; ++i)
  {
    unsigned count, res;
    set_current_state(TASK_INTERRUPTIBLE);
    schedule_timeout(1);
    foo();
    local_irq_disable();
    count = foo();
    local_irq_enable();
    res = count >> 8;
    if (res < MAX) ++lat[res]; else printk(KERN_ALERT "OUT OF RANGE\n");
  }

  for (i=0; i < MAX; ++i)
    if (lat[i] != 0) printk(KERN_ALERT "%d %d\n", i<<8, lat[i]);

  return 0;
}

static void hello_exit(void)
{
  printk(KERN_ALERT "EXIT\n");
}

module_init(hello_init);
module_exit(hello_exit);