mlfqs-fair.c

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/** Measures the correctness of the "nice" implementation.
 
   The "fair" tests run either 2 or 20 threads all niced to 0.
   The threads should all receive approximately the same number
   of ticks.  Each test runs for 30 seconds, so the ticks should
   also sum to approximately 30 * 100 == 3000 ticks.
 
   The mlfqs-nice-2 test runs 2 threads, one with nice 0, the
   other with nice 5, which should receive 1,904 and 1,096 ticks,
   respectively, over 30 seconds.
 
   The mlfqs-nice-10 test runs 10 threads with nice 0 through 9.
   They should receive 672, 588, 492, 408, 316, 232, 152, 92, 40,
   and 8 ticks, respectively, over 30 seconds.
 
   (The above are computed via simulation in mlfqs.pm.) */
 
#include <stdio.h>
#include <inttypes.h>
#include "tests/threads/tests.h"
#include "threads/init.h"
#include "threads/malloc.h"
#include "threads/palloc.h"
#include "threads/synch.h"
#include "threads/thread.h"
#include "devices/timer.h"
 
static void test_mlfqs_fair (int thread_cnt, int nice_min, int nice_step);
 
void
test_mlfqs_fair_2 (void) 
{
  test_mlfqs_fair (2, 0, 0);
}
 
void
test_mlfqs_fair_20 (void) 
{
  test_mlfqs_fair (20, 0, 0);
}
 
void
test_mlfqs_nice_2 (void) 
{
  test_mlfqs_fair (2, 0, 5);
}
 
void
test_mlfqs_nice_10 (void) 
{
  test_mlfqs_fair (10, 0, 1);
}
␌
#define MAX_THREAD_CNT 20
 
struct thread_info 
  {
    int64_t start_time;
    int tick_count;
    int nice;
  };
 
static void load_thread (void *aux);
 
static void
test_mlfqs_fair (int thread_cnt, int nice_min, int nice_step)
{
  struct thread_info info[MAX_THREAD_CNT];
  int64_t start_time;
  int nice;
  int i;
 
  ASSERT (thread_mlfqs);
  ASSERT (thread_cnt <= MAX_THREAD_CNT);
  ASSERT (nice_min >= -10);
  ASSERT (nice_step >= 0);
  ASSERT (nice_min + nice_step * (thread_cnt - 1) <= 20);
 
  thread_set_nice (-20);
 
  start_time = timer_ticks ();
  msg ("Starting %d threads...", thread_cnt);
  nice = nice_min;
  for (i = 0; i < thread_cnt; i++) 
    {
      struct thread_info *ti = &info[i];
      char name[16];
 
      ti->start_time = start_time;
      ti->tick_count = 0;
      ti->nice = nice;
 
      snprintf(name, sizeof name, "load %d", i);
      thread_create (name, PRI_DEFAULT, load_thread, ti);
 
      nice += nice_step;
    }
  msg ("Starting threads took %"PRId64" ticks.", timer_elapsed (start_time));
 
  msg ("Sleeping 40 seconds to let threads run, please wait...");
  timer_sleep (40 * TIMER_FREQ);
  
  for (i = 0; i < thread_cnt; i++)
    msg ("Thread %d received %d ticks.", i, info[i].tick_count);
}
 
static void
load_thread (void *ti_) 
{
  struct thread_info *ti = ti_;
  int64_t sleep_time = 5 * TIMER_FREQ;
  int64_t spin_time = sleep_time + 30 * TIMER_FREQ;
  int64_t last_time = 0;
 
  thread_set_nice (ti->nice);
  timer_sleep (sleep_time - timer_elapsed (ti->start_time));
  while (timer_elapsed (ti->start_time) < spin_time) 
    {
      int64_t cur_time = timer_ticks ();
      if (cur_time != last_time)
        ti->tick_count++;
      last_time = cur_time;
    }
}