1 files changed, 22 insertions, 2 deletions

diff --git a/threads/thread.c b/threads/thread.c
index 845f059..3fefbd8 100644
--- a/threads/thread.c
+++ b/threads/thread.c
@@ -71,6 +71,16 @@ static void schedule (void);
 void thread_schedule_tail (struct thread *prev);
 static tid_t allocate_tid (void);
 
+//TODO: should take donated priority into account
+static bool
+ready_list_cmp_less(const struct list_elem *a, const struct list_elem *b,
+  void *AUX UNUSED)
+{
+  struct thread *t1 = list_entry (a, struct thread, elem);
+  struct thread *t2 = list_entry (b, struct thread, elem);
+  return (t1->priority > t2->priority);
+}
+
 /* Initializes the threading system by transforming the code
    that's currently running into a thread.  This can't work in
    general and it is possible in this case only because loader.S
@@ -212,6 +222,7 @@ thread_create (const char *name, int priority,
 
   /* Add to run queue. */
   thread_unblock (t);
+  thread_yield ();
 
   return tid;
 }
@@ -249,7 +260,8 @@ thread_unblock (struct thread *t)
 
   old_level = intr_disable ();
   ASSERT (t->status == THREAD_BLOCKED);
-  list_push_back (&ready_list, &t->elem);
+  /* add thread to our ordered ready_list */
+  list_insert_ordered (&ready_list, &t->elem, &ready_list_cmp_less, NULL);
   t->status = THREAD_READY;
   intr_set_level (old_level);
 }
@@ -320,7 +332,7 @@ thread_yield (void)
 
   old_level = intr_disable ();
   if (cur != idle_thread)
-    list_push_back (&ready_list, &cur->elem);
+    list_insert_ordered (&ready_list, &cur->elem, &ready_list_cmp_less, NULL);
   cur->status = THREAD_READY;
   schedule ();
   intr_set_level (old_level);
@@ -348,6 +360,14 @@ void
 thread_set_priority (int new_priority)
 {
   thread_current ()->priority = new_priority;
+
+  /* compare priority with the highest priority in the list */
+  if (!list_empty (&ready_list))
+  {
+    struct thread *t = list_entry (list_front (&ready_list), struct thread, elem);
+    if (t->priority > thread_current ()->priority)
+      thread_yield();
+  }
 }
 
 /* Returns the current thread's priority. */