X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fthreads%2Fthread.c;h=ae92e1d646dc50d50ce02d26747ca12a8bd82236;hb=6070611faac84bdf95c4405b3970c6928202f26b;hp=0861e29533b67a59e3b4a248311735deeb2b6d5b;hpb=f0612244c44f4b4f0bc79e3fc882e9f74bd4a3f4;p=pintos-anon

diff --git a/src/threads/thread.c b/src/threads/thread.c
index 0861e29..ae92e1d 100644
--- a/src/threads/thread.c
+++ b/src/threads/thread.c
@@ -13,7 +13,6 @@
 #include "threads/synch.h"
 #ifdef USERPROG
 #include "userprog/process.h"
-#include "userprog/gdt.h"
 #endif
 
 /* Random value for struct thread's `magic' member.
@@ -42,25 +41,29 @@ struct kernel_thread_frame
     void *aux;                  /* Auxiliary data for function. */
   };
 
+/* Statistics. */
+static long long idle_ticks;    /* # of timer ticks spent idle. */
+static long long kernel_ticks;  /* # of timer ticks in kernel threads. */
+static long long user_ticks;    /* # of timer ticks in user programs. */
+
 static void kernel_thread (thread_func *, void *aux);
 
 static void idle (void *aux UNUSED);
 static struct thread *running_thread (void);
 static struct thread *next_thread_to_run (void);
-static struct thread *new_thread (const char *name, int priority);
 static void init_thread (struct thread *, const char *name, int priority);
 static bool is_thread (struct thread *);
 static void *alloc_frame (struct thread *, size_t size);
-static void destroy_thread (struct thread *);
 static void schedule (void);
 void schedule_tail (struct thread *prev);
 static tid_t allocate_tid (void);
 
 /* Initializes the threading system by transforming the code
-   that's currently running into a thread.  Note that this is
-   possible only because the loader was careful to put the bottom
-   of the stack at a page boundary; it won't work in general.
-   Also initializes the run queue.
+   that's currently running into a thread.  This can't work in
+   general and it is possible in this case only because loader.S
+   was careful to put the bottom of the stack at a page boundary.
+
+   Also initializes the run queue and the tid lock.
 
    After calling this function, be sure to initialize the page
    allocator before trying to create any threads with
@@ -71,15 +74,13 @@ thread_init (void)
   ASSERT (intr_get_level () == INTR_OFF);
 
   lock_init (&tid_lock, "tid");
+  list_init (&ready_list);
 
   /* Set up a thread structure for the running thread. */
   initial_thread = running_thread ();
   init_thread (initial_thread, "main", PRI_DEFAULT);
   initial_thread->status = THREAD_RUNNING;
   initial_thread->tid = allocate_tid ();
-
-  /* Initialize run queue. */
-  list_init (&ready_list);
 }
 
 /* Starts preemptive thread scheduling by enabling interrupts.
@@ -91,15 +92,41 @@ thread_start (void)
   intr_enable ();
 }
 
+/* Called by the timer interrupt handler at each timer tick to
+   update statistics. */
+void
+thread_tick (void) 
+{
+  struct thread *t = thread_current ();
+  if (t == idle_thread)
+    idle_ticks++;
+#ifdef USERPROG
+  else if (t->pagedir != NULL)
+    user_ticks++;
+#endif
+  else
+    kernel_ticks++;
+}
+
+/* Prints thread statistics. */
+void
+thread_print_stats (void) 
+{
+  printf ("Thread: %lld idle ticks, %lld kernel ticks, %lld user ticks\n",
+          idle_ticks, kernel_ticks, user_ticks);
+}
+
 /* Creates a new kernel thread named NAME with the given initial
    PRIORITY, which executes FUNCTION passing AUX as the argument,
-   and adds it to the ready queue.  If thread_start() has been
-   called, then the new thread may be scheduled before
-   thread_create() returns.  It could even exit before
-   thread_create() returns.  Use a semaphore or some other form
-   of synchronization if you need to ensure ordering.  Returns
-   the thread identifier for the new thread, or TID_ERROR if
-   creation fails.
+   and adds it to the ready queue.  Returns the thread identifier
+   for the new thread, or TID_ERROR if creation fails.
+
+   If thread_start() has been called, then the new thread may be
+   scheduled before thread_create() returns.  It could even exit
+   before thread_create() returns.  Contrariwise, the original
+   thread may run for any amount of time before the new thread is
+   scheduled.  Use a semaphore or some other form of
+   synchronization if you need to ensure ordering.
 
    The code provided sets the new thread's `priority' member to
    PRIORITY, but no actual priority scheduling is implemented.
@@ -116,10 +143,14 @@ thread_create (const char *name, int priority,
 
   ASSERT (function != NULL);
 
-  t = new_thread (name, priority);
+  /* Allocate thread. */
+  t = palloc_get_page (PAL_ZERO);
   if (t == NULL)
     return TID_ERROR;
-  tid = t->tid;
+
+  /* Initialize thread. */
+  init_thread (t, name, priority);
+  tid = t->tid = allocate_tid ();
 
   /* Stack frame for kernel_thread(). */
   kf = alloc_frame (t, sizeof *kf);
@@ -141,9 +172,25 @@ thread_create (const char *name, int priority,
   return tid;
 }
 
-/* Transitions a blocked thread T from its current state to the
-   ready-to-run state.  This is an error if T is not blocked.
-   (Use thread_yield() to make the running thread ready.) */
+/* Puts the current thread to sleep.  It will not be scheduled
+   again until awoken by thread_unblock().
+
+   This function must be called with interrupts turned off.  It
+   is usually a better idea to use one of the synchronization
+   primitives in synch.h. */
+void
+thread_block (void) 
+{
+  ASSERT (!intr_context ());
+  ASSERT (intr_get_level () == INTR_OFF);
+
+  thread_current ()->status = THREAD_BLOCKED;
+  schedule ();
+}
+
+/* Transitions a blocked thread T to the ready-to-run state.
+   This is an error if T is not blocked.  (Use thread_yield() to
+   make the running thread ready.) */
 void
 thread_unblock (struct thread *t) 
 {
@@ -198,6 +245,10 @@ thread_exit (void)
 {
   ASSERT (!intr_context ());
 
+#ifdef USERPROG
+  process_exit ();
+#endif
+
   /* Just set our status to dying and schedule another process.
      We will be destroyed during the call to schedule_tail(). */
   intr_disable ();
@@ -223,20 +274,29 @@ thread_yield (void)
   intr_set_level (old_level);
 }
 
-/* Puts the current thread to sleep.  It will not be scheduled
-   again until awoken by thread_unblock().
+/* Waits for the thread with the specified TID to terminate.  If
+   TID has already terminated or TID does not refer to an
+   immediate child of the current thread, returns immediately.
 
-   This function must be called with interrupts turned off.  It
-   is usually a better idea to use one of the synchronization
-   primitives in synch.h. */
+   This function will be implemented in problem 1-2.  For now, it
+   does nothing. */
 void
-thread_block (void) 
+thread_join (tid_t child_tid UNUSED) 
 {
-  ASSERT (!intr_context ());
-  ASSERT (intr_get_level () == INTR_OFF);
+}
 
-  thread_current ()->status = THREAD_BLOCKED;
-  schedule ();
+/* Sets the current thread's priority to NEW_PRIORITY. */
+void
+thread_set_priority (int new_priority) 
+{
+  thread_current ()->priority = new_priority;
+}
+
+/* Returns the current thread's priority. */
+int
+thread_get_priority (void) 
+{
+  return thread_current ()->priority;
 }
 
 /* Idle thread.  Executes when no other thread is ready to run. */
@@ -252,7 +312,8 @@ idle (void *aux UNUSED)
       thread_block ();
       intr_enable ();
 
-      /* Use CPU `hlt' instruction to wait for interrupt. */
+      /* Use CPU `hlt' instruction to wait for interrupt.
+         See [IA32-v2a] "HLT" and [IA32-v3] 7.7. */
       asm ("hlt");
     }
 }
@@ -278,7 +339,7 @@ running_thread (void)
      down to the start of a page.  Because `struct thread' is
      always at the beginning of a page and the stack pointer is
      somewhere in the middle, this locates the curent thread. */
-  asm ("movl %%esp, %0\n" : "=g" (esp));
+  asm ("mov %0, %%esp" : "=g" (esp));
   return pg_round_down (esp);
 }
 
@@ -289,22 +350,6 @@ is_thread (struct thread *t)
   return t != NULL && t->magic == THREAD_MAGIC;
 }
 
-/* Creates a new thread named NAME as a child of the running
-   thread.  Returns the new thread if successful or a null
-   pointer on failure. */
-static struct thread *
-new_thread (const char *name, int priority)
-{
-  struct thread *t = palloc_get (PAL_ZERO);
-  if (t != NULL) 
-    {
-      init_thread (t, name, priority);
-      t->tid = allocate_tid ();
-    }
-
-  return t;
-}
-
 /* Does basic initialization of T as a blocked thread named
    NAME. */
 static void
@@ -349,20 +394,6 @@ next_thread_to_run (void)
     return list_entry (list_pop_front (&ready_list), struct thread, elem);
 }
 
-/* Destroys T, which must not be the running thread. */
-static void
-destroy_thread (struct thread *t) 
-{
-  ASSERT (is_thread (t));
-  ASSERT (t != thread_current ());
-
-#ifdef USERPROG
-  process_destroy (t);
-#endif
-  if (t != initial_thread)
-    palloc_free (t);
-}
-
 /* Completes a thread switch by activating the new thread's page
    tables, and, if the previous thread is dying, destroying it.
 
@@ -373,6 +404,10 @@ destroy_thread (struct thread *t)
    the first time a thread is scheduled it is called by
    switch_entry() (see switch.S).
 
+   It's not safe to call printf() until the thread switch is
+   complete.  In practice that means that printf()s should be
+   added at the end of the function.
+
    After this function and its caller returns, the thread switch
    is complete. */
 void
@@ -390,17 +425,24 @@ schedule_tail (struct thread *prev)
   process_activate ();
 #endif
 
-  /* If the thread we switched from is dying, destroy it.
-     This must happen late because it's not a good idea to
-     e.g. destroy the page table you're currently using. */
+  /* If the thread we switched from is dying, destroy its struct
+     thread.  This must happen late so that thread_exit() doesn't
+     pull out the rug under itself. */
   if (prev != NULL && prev->status == THREAD_DYING) 
-    destroy_thread (prev);
+    {
+      ASSERT (prev != cur);
+      if (prev != initial_thread)
+        palloc_free_page (prev);
+    }
 }
 
 /* Schedules a new process.  At entry, interrupts must be off and
    the running process's state must have been changed from
    running to some other state.  This function finds another
-   thread to run and switches to it. */
+   thread to run and switches to it.
+
+   It's not safe to call printf() until schedule_tail() has
+   completed. */
 static void
 schedule (void) 
 {