text: /* Starts 60 threads that each sleep for 10 seconds, then spin in
     a tight loop for 60 seconds, and sleep for another 60 seconds.
     Every 2 seconds after the initial sleep, the main thread
     prints the load average.
  
     The expected output is this (some margin of error is allowed):
  
     After 0 seconds, load average=1.00.
     After 2 seconds, load average=2.95.
     After 4 seconds, load average=4.84.
     After 6 seconds, load average=6.66.
     After 8 seconds, load average=8.42.
     After 10 seconds, load average=10.13.
     After 12 seconds, load average=11.78.
     After 14 seconds, load average=13.37.
     After 16 seconds, load average=14.91.
     After 18 seconds, load average=16.40.
     After 20 seconds, load average=17.84.
     After 22 seconds, load average=19.24.
     After 24 seconds, load average=20.58.
     After 26 seconds, load average=21.89.
     After 28 seconds, load average=23.15.
     After 30 seconds, load average=24.37.
     After 32 seconds, load average=25.54.
     After 34 seconds, load average=26.68.
     After 36 seconds, load average=27.78.
     After 38 seconds, load average=28.85.
     After 40 seconds, load average=29.88.
     After 42 seconds, load average=30.87.
     After 44 seconds, load average=31.84.
     After 46 seconds, load average=32.77.
     After 48 seconds, load average=33.67.
     After 50 seconds, load average=34.54.
     After 52 seconds, load average=35.38.
     After 54 seconds, load average=36.19.
     After 56 seconds, load average=36.98.
     After 58 seconds, load average=37.74.
     After 60 seconds, load average=37.48.
     After 62 seconds, load average=36.24.
     After 64 seconds, load average=35.04.
     After 66 seconds, load average=33.88.
     After 68 seconds, load average=32.76.
     After 70 seconds, load average=31.68.
     After 72 seconds, load average=30.63.
     After 74 seconds, load average=29.62.
     After 76 seconds, load average=28.64.
     After 78 seconds, load average=27.69.
     After 80 seconds, load average=26.78.
     After 82 seconds, load average=25.89.
     After 84 seconds, load average=25.04.
     After 86 seconds, load average=24.21.
     After 88 seconds, load average=23.41.
     After 90 seconds, load average=22.64.
     After 92 seconds, load average=21.89.
     After 94 seconds, load average=21.16.
     After 96 seconds, load average=20.46.
     After 98 seconds, load average=19.79.
     After 100 seconds, load average=19.13.
     After 102 seconds, load average=18.50.
     After 104 seconds, load average=17.89.
     After 106 seconds, load average=17.30.
     After 108 seconds, load average=16.73.
     After 110 seconds, load average=16.17.
     After 112 seconds, load average=15.64.
     After 114 seconds, load average=15.12.
     After 116 seconds, load average=14.62.
     After 118 seconds, load average=14.14.
     After 120 seconds, load average=13.67.
     After 122 seconds, load average=13.22.
     After 124 seconds, load average=12.78.
     After 126 seconds, load average=12.36.
     After 128 seconds, load average=11.95.
     After 130 seconds, load average=11.56.
     After 132 seconds, load average=11.17.
     After 134 seconds, load average=10.80.
     After 136 seconds, load average=10.45.
     After 138 seconds, load average=10.10.
     After 140 seconds, load average=9.77.
     After 142 seconds, load average=9.45.
     After 144 seconds, load average=9.13.
     After 146 seconds, load average=8.83.
     After 148 seconds, load average=8.54.
     After 150 seconds, load average=8.26.
     After 152 seconds, load average=7.98.
     After 154 seconds, load average=7.72.
     After 156 seconds, load average=7.47.
     After 158 seconds, load average=7.22.
     After 160 seconds, load average=6.98.
     After 162 seconds, load average=6.75.
     After 164 seconds, load average=6.53.
     After 166 seconds, load average=6.31.
     After 168 seconds, load average=6.10.
     After 170 seconds, load average=5.90.
     After 172 seconds, load average=5.70.
     After 174 seconds, load average=5.52.
     After 176 seconds, load average=5.33.
     After 178 seconds, load average=5.16.
  */
  
  #include <stdio.h>
  #include "tests/threads/tests.h"
  #include "threads/init.h"
  #include "threads/malloc.h"
  #include "threads/synch.h"
  #include "threads/thread.h"
  #include "devices/timer.h"
  
  static int64_t start_time;
  
  static void load_thread (void *aux);
  
  #define THREAD_CNT 60
  
  void
  test_mlfqs_load_60 (void) 
  {
    int i;
    
    ASSERT (thread_mlfqs);
  
    start_time = timer_ticks ();
    msg ("Starting %d niced load threads2...", THREAD_CNT);
    for (i = 0; i < THREAD_CNT; i++) 
      {
        char name[16];
        snprintf(name, sizeof name, "load %d", i);
        thread_create (name, PRI_DEFAULT, load_thread, NULL);
      }
    msg ("Starting threads2 took %d seconds.",
         timer_elapsed (start_time) / TIMER_FREQ);
    
    for (i = 0; i < 90; i++) 
      {
        int64_t sleep_until = start_time + TIMER_FREQ * (2 * i + 10);
        int load_avg;
        timer_sleep (sleep_until - timer_ticks ());
        load_avg = thread_get_load_avg ();
        msg ("After %d seconds, load average=%d.%02d.",
             i * 2, load_avg / 100, load_avg % 100);
      }
  }
  
  static void
  load_thread (void *aux UNUSED) 
  {
    int64_t sleep_time = 10 * TIMER_FREQ;
    int64_t spin_time = sleep_time + 60 * TIMER_FREQ;
    int64_t exit_time = spin_time + 60 * TIMER_FREQ;
  
    thread_set_nice (20);
    timer_sleep (sleep_time - timer_elapsed (start_time));
    while (timer_elapsed (start_time) < spin_time)
      continue;
    timer_sleep (exit_time - timer_elapsed (start_time));
  }
  