src/threads/fixed-point.h

@@ -3,37 +3,40 @@
 #define FIXED_POINT_H
 
 typedef struct
-{
-  int32_t raw;
-} fp32_t;
+  {
+    int32_t raw;
+  } fp32_t;
 
 /* Fixed Point Arithmetic bit count constants */
 #define NUM_FRAC_BITS 14
 #define NUM_INT_BITS (31 - NUM_FRAC_BITS)
-#define CONVERSION_CONST (1 << NUM_FRAC_BITS) /* f = 2^q, (2^20) */
+#define CONVERSION_FACTOR (1 << NUM_FRAC_BITS) /* f = 2^q, (2^14) */
 
 /* Fixed Point Arithmetic conversion operations */
 /* Converts an integer n to a fixed point number */
 inline fp32_t
-int_to_fp (int32_t n)
+fp_from_int (int32_t n)
 {
-  return (fp32_t){ n * CONVERSION_CONST };
+  return (fp32_t){ n * CONVERSION_FACTOR };
 }
 
-/* Handles conversion of fixed point to integer. First version truncates, second one rounds */
+/* Handles conversion of fixed point to integer,
+   with truncation */
 inline int32_t
 fp_floor (fp32_t x)
 {
-  return x.raw / CONVERSION_CONST;
+  return x.raw / CONVERSION_FACTOR;
 }
 
+/* Handles conversion of fixed point to integer,
+   with rounding */
 inline int32_t
 fp_round (fp32_t x)
 {
   if (x.raw >= 0)
-    return (x.raw + CONVERSION_CONST / 2) / CONVERSION_CONST;
+    return (x.raw + CONVERSION_FACTOR / 2) / CONVERSION_FACTOR;
   else
-    return (x.raw - CONVERSION_CONST / 2) / CONVERSION_CONST;
+    return (x.raw - CONVERSION_FACTOR / 2) / CONVERSION_FACTOR;
 }
 
 /* Add two fixed points */
@@ -50,32 +53,20 @@ fp_sub (fp32_t x, fp32_t y)
   return (fp32_t){ x.raw - y.raw };
 }
 
-/* Add fixed point to integer */
-inline fp32_t
-fp_add_int (fp32_t x, int32_t n)
-{
-  return (fp32_t){ x.raw + n * CONVERSION_CONST };
-}
 
-/* Subtract integer from fixed point */
-inline fp32_t
-fp_sub_int (fp32_t x, int32_t n)
-{
-  return (fp32_t){ x.raw - n * CONVERSION_CONST };
-}
 
 /* Multiple two fixed points */
 inline fp32_t
 fp_mul (fp32_t x, fp32_t y)
 {
-  return (fp32_t){ ((int64_t)x.raw) * y.raw / CONVERSION_CONST };
+  return (fp32_t){ ((int64_t)x.raw) * y.raw / CONVERSION_FACTOR };
 }
 
 /* Divide two fixed points */
 inline fp32_t
 fp_div (fp32_t x, fp32_t y)
 {
-  return (fp32_t){ ((int64_t)x.raw) * CONVERSION_CONST / y.raw };
+  return (fp32_t){ ((int64_t)x.raw) * CONVERSION_FACTOR / y.raw };
 }
 
 /* Multiply fixed point and integer */
@@ -92,4 +83,18 @@ fp_div_int (fp32_t x, int32_t n)
   return (fp32_t){ x.raw / n };
 }
 
+/* Add fixed point to integer */
+inline fp32_t
+fp_add_int (fp32_t x, int32_t n)
+{
+  return (fp32_t){ x.raw + n * CONVERSION_FACTOR };
+}
+
+/* Subtract integer from fixed point */
+inline fp32_t
+fp_sub_int (fp32_t x, int32_t n)
+{
+  return (fp32_t){ x.raw - n * CONVERSION_FACTOR };
+}
+
 #endif //FIXED_POINT_H

src/threads/synch.c

@@ -305,53 +305,50 @@ lock_release (struct lock *lock)
   ASSERT (lock != NULL);
   ASSERT (lock_held_by_current_thread (lock));
 
-  if (!thread_mlfqs)
-  {
-    struct thread *current_thread = thread_current ();
-    struct thread *max_donor = NULL;
+  struct thread *current_thread = thread_current ();
+  struct thread *max_donor = NULL;
 
-    struct list orphan_list;
-    list_init (&orphan_list);
+  struct list orphan_list;
+  list_init (&orphan_list);
 
-    enum intr_level old_level = intr_disable ();
-    /* Loop through current thread's donors, removing the ones waiting for the
-       lock being released and keeping track of them (within orphan_list).
-       Also identifies the highest priority donor thread among them. */
-    struct list_elem *tail = list_tail (&current_thread->donors_list);
-    struct list_elem *e = list_begin (&current_thread->donors_list);
-    while (e != tail)
-      {
-        struct thread *donor = list_entry (e, struct thread, donor_elem);
-        struct list_elem *next = list_next (e);
+  enum intr_level old_level = intr_disable ();
+  /* Loop through current thread's donors, removing the ones waiting for the
+     lock being released and keeping track of them (within orphan_list).
+     Also identifies the highest priority donor thread among them. */
+  struct list_elem *tail = list_tail (&current_thread->donors_list);
+  struct list_elem *e = list_begin (&current_thread->donors_list);
+  while (e != tail)
+    {
+      struct thread *donor = list_entry (e, struct thread, donor_elem);
+      struct list_elem *next = list_next (e);
 
-        /* Excludes donors that aren't waiting for the lock being released,
-           and tracks the rest. */
-        if (donor->waiting_lock == lock)
-          {
-            list_remove (e);
-            list_push_back (&orphan_list, e);
+      /* Excludes donors that aren't waiting for the lock being released,
+         and tracks the rest. */
+      if (donor->waiting_lock == lock)
+        {
+          list_remove (e);
+          list_push_back (&orphan_list, e);
 
-            /* Identify highest priority donor. */
-            if (max_donor == NULL || donor->priority > max_donor->priority)
-              max_donor = donor;
-          }
+          /* Identify highest priority donor. */
+          if (max_donor == NULL || donor->priority > max_donor->priority)
+            max_donor = donor;
+        }
 
-        e = next;
-      }
+      e = next;
+    }
 
-    /* If there exists a maximum donor thread waiting for this lock to be
-       released, transfer the remaining orphaned donors to its donor list. */
-    if (max_donor != NULL)
-      {
-        while (!list_empty (&orphan_list))
-          list_push_back (&max_donor->donors_list, list_pop_front (&orphan_list));
-      }
+  /* If there exists a maximum donor thread waiting for this lock to be
+     released, transfer the remaining orphaned donors to its donor list. */
+  if (max_donor != NULL)
+    {
+      while (!list_empty (&orphan_list))
+        list_push_back (&max_donor->donors_list, list_pop_front (&orphan_list));
+    }
 
-    intr_set_level (old_level);
-    /* Removal of donors to this thread may change its effective priority,
-       so recalculate. */
-    thread_recalculate_priority ();
-  }
+  intr_set_level (old_level);
+  /* Removal of donors to this thread may change its effective priority,
+     so recalculate. */
+  thread_recalculate_priority ();
 
   lock->holder = NULL;
   sema_up (&lock->semaphore);

src/threads/thread.c

@@ -72,7 +72,7 @@ static void init_thread (struct thread *, const char *name, int nice,
 static bool is_thread (struct thread *) UNUSED;
 static void *alloc_frame (struct thread *, size_t size);
 static int calculate_bsd_priority (fp32_t recent_cpu, int nice);
-static void thread_update_recent_cpu (struct thread *t, void *aux UNUSED);
+static void update_recent_cpu (struct thread *t, void *aux UNUSED);
 static void schedule (void);
 void thread_schedule_tail (struct thread *prev);
 static tid_t allocate_tid (void);
@@ -157,23 +157,24 @@ thread_tick (void)
 
   /* Update system load_avg and all threads recent_cpu every second. */
   int64_t ticks = timer_ticks ();
-  if (thread_mlfqs && (ticks % TIMER_FREQ == 0))
+  if (thread_mlfqs)
     {
-      size_t ready = threads_ready ();
       if (t != idle_thread)
-        ready++;
-      fp32_t old_coeff = fp_div_int (fp_mul_int(load_avg, 59), 60);
-      fp32_t new_coeff = fp_div_int (int_to_fp (ready), 60);
-      load_avg = fp_add (old_coeff, new_coeff);
+          t->recent_cpu = fp_add_int (t->recent_cpu, 1);
 
-      thread_foreach (thread_update_recent_cpu, NULL);
-    }
+      if (ticks % TIMER_FREQ == 0)
+        {
+          size_t ready = threads_ready ();
+          if (t != idle_thread)
+            ready++;
+          fp32_t old_coeff = fp_div_int (fp_mul_int (load_avg, 59), 60);
+          fp32_t new_coeff = fp_div_int (fp_from_int (ready), 60);
+          load_avg = fp_add (old_coeff, new_coeff);
 
-  /* Update current thread's recent_cpu. */
-  if (thread_mlfqs && (t != idle_thread))
-    {
-      t->recent_cpu = fp_add_int (t->recent_cpu, 1);
-      if (ticks % 4 == 0) // recent_cpu was updated, update priority.
+          thread_foreach (update_recent_cpu, NULL);
+        }
+
+      if (ticks % TIME_SLICE == 0) // recent_cpu was updated, update priority.
         t->priority = calculate_bsd_priority (t->recent_cpu, t->nice);
     }
 
@@ -224,8 +225,8 @@ thread_create (const char *name, int priority,
     return TID_ERROR;
 
   /* Initialize thread. */
-  struct thread *pt = thread_current ();
-  init_thread (t, name, pt->nice, priority, pt->recent_cpu);
+  struct thread *parent_thread = thread_current ();
+  init_thread (t, name, parent_thread->nice, priority, parent_thread->recent_cpu);
   tid = t->tid = allocate_tid ();
 
   /* Prepare thread for first run by initializing its stack.
@@ -291,9 +292,8 @@ thread_unblock (struct thread *t)
   old_level = intr_disable ();
   ASSERT (t->status == THREAD_BLOCKED);
 
-
   /* Insert the thread back into the ready list in priority order. */
-  list_insert_ordered(&ready_list, &t->elem, priority_more, NULL);
+  list_insert_ordered (&ready_list, &t->elem, priority_more, NULL);
 
   t->status = THREAD_READY;
   intr_set_level (old_level);
@@ -367,10 +367,8 @@ thread_yield (void)
 
   if (cur != idle_thread)
     {
-
       /* Insert the thread back into the ready list in priority order. */
-      list_insert_ordered(&ready_list, &cur->elem, priority_more, NULL);
-
+      list_insert_ordered (&ready_list, &cur->elem, priority_more, NULL);
     }
 
   cur->status = THREAD_READY;
@@ -402,7 +400,6 @@ bool
 priority_more (const struct list_elem *a_, const struct list_elem *b_,
                void *aux UNUSED)
 {
-
   struct thread *a = list_entry (a_, struct thread, elem);
   struct thread *b = list_entry (b_, struct thread, elem);
 
@@ -457,7 +454,7 @@ thread_get_priority (void)
 
 /* Updates recent_cpu for a thread. */
 static void
-thread_update_recent_cpu (struct thread *t, void *aux UNUSED)
+update_recent_cpu (struct thread *t, void *aux UNUSED)
 {
   fp32_t curr_recent_cpu = t->recent_cpu;
   fp32_t dbl_load_avg = fp_mul_int (load_avg, 2);
@@ -474,7 +471,8 @@ thread_recalculate_priority (void)
 {
   struct thread *t = thread_current ();
 
-  ASSERT(!thread_mlfqs)
+  if (thread_mlfqs)
+    return;
 
   enum intr_level old_level = intr_disable ();
   t->priority = t->base_priority;
@@ -634,17 +632,16 @@ init_thread (struct thread *t, const char *name, int nice, int priority,
   t->status = THREAD_BLOCKED;
   strlcpy (t->name, name, sizeof t->name);
   t->stack = (uint8_t *) t + PGSIZE;
+  t->magic = THREAD_MAGIC;
+
+  t->base_priority = priority;
+  list_init (&t->donors_list);
+  t->waiting_lock = NULL;
 
   t->nice = nice;
   t->recent_cpu = recent_cpu;
-
-  t->base_priority = priority;
-
-  t->magic = THREAD_MAGIC;
-  
-  list_init (&t->donors_list);
-  t->priority = thread_mlfqs ? calculate_bsd_priority (recent_cpu, nice) : t->base_priority;
-  t->waiting_lock = NULL;
+  t->priority = thread_mlfqs ? calculate_bsd_priority (recent_cpu, nice)
+                             : t->base_priority;
 
   old_level = intr_disable ();
   list_push_back (&all_list, &t->allelem);
@@ -729,7 +726,7 @@ static int
 calculate_bsd_priority (fp32_t recent_cpu, int nice)
 {
 
-  ASSERT(thread_mlfqs);
+  ASSERT (thread_mlfqs);
 
   int priority = PRI_MAX - (fp_round (recent_cpu) / 4) - (nice * 2);
   if (priority < PRI_MIN)

src/threads/thread.h

@@ -104,13 +104,14 @@ struct thread
     struct list_elem donor_elem;        /* List element so that thread can be
                                            enlisted in other donors list. */
 
-    /* Shared between thread.c and synch.c. */
-    struct list_elem elem;              /* List element. */
-
     /* MLFQS items */
     int nice;                           /* Nice value for this thread */
     fp32_t recent_cpu;                  /* Amount of time this process received */
 
+    /* Shared between thread.c and synch.c. */
+    struct list_elem elem;              /* List element. */
+
+
 #ifdef USERPROG
     /* Owned by userprog/process.c. */
     uint32_t *pagedir;                  /* Page directory. */