Project HW #2

pintos-env/pintos/devices/timer.c

@@ -1,3 +1,6 @@
+// Author: Claudio Maggioni
+// Author: Tommaso Rodolfo Masera
+
 #include "devices/timer.h"
 #include <debug.h>
 #include <inttypes.h>
@@ -7,6 +10,8 @@
 #include "threads/interrupt.h"
 #include "threads/synch.h"
 #include "threads/thread.h"
+#include "threads/malloc.h"
+#include "../lib/kernel/list.h"
 
 /* See [8254] for hardware details of the 8254 timer chip. */
 
@@ -89,11 +94,12 @@ timer_elapsed (int64_t then)
 void
 timer_sleep (int64_t ticks)
 {
-  int64_t start = timer_ticks ();
+  if (ticks <= 0)
+    return;
 
-  ASSERT (intr_get_level () == INTR_ON);
-  while (timer_elapsed (start) < ticks) 
-    thread_yield ();
+  ASSERT (intr_get_level() == INTR_ON);
+
+  thread_sleep(ticks);
 }
 
 /* Sleeps for approximately MS milliseconds.  Interrupts must be
@@ -171,7 +177,9 @@ static void
 timer_interrupt (struct intr_frame *args UNUSED)
 {
   ticks++;
-  thread_tick ();
+
+  thread_unsleep();
+  thread_tick();
 }
 
 /* Returns true if LOOPS iterations waits for more than one timer

pintos-env/pintos/threads/thread.c

@@ -1,3 +1,6 @@
+// Author: Claudio Maggioni
+// Author: Tommaso Rodolfo Masera
+
 #include "threads/thread.h"
 #include <debug.h>
 #include <stddef.h>
@@ -11,6 +14,7 @@
 #include "threads/switch.h"
 #include "threads/synch.h"
 #include "threads/vaddr.h"
+#include "devices/timer.h"
 #ifdef USERPROG
 #include "userprog/process.h"
 #endif
@@ -37,6 +41,8 @@ static struct thread *initial_thread;
 /* Lock used by allocate_tid(). */
 static struct lock tid_lock;
 
+static struct list sleeping;
+
 /* Stack frame for kernel_thread(). */
 struct kernel_thread_frame
   {
@@ -98,6 +104,46 @@ thread_init (void)
   init_thread (initial_thread, "main", PRI_DEFAULT);
   initial_thread->status = THREAD_RUNNING;
   initial_thread->tid = allocate_tid ();
+
+  list_init(&sleeping);
+}
+
+static bool
+earlier_wakeup(const struct list_elem* a, const struct list_elem* b, void* aux UNUSED) {
+  return list_entry(a, struct thread, elem)->wakeup <
+    list_entry(b, struct thread, elem)->wakeup;
+}
+
+void
+thread_sleep(uint64_t ticks) {
+  enum intr_level old_level = intr_disable();
+  struct thread* cur = thread_current();
+  cur->wakeup = timer_ticks() + ticks;
+  // printf("sleeping insert %X\n", cur);
+  list_insert_ordered(&sleeping, &(cur->elem), earlier_wakeup, NULL);
+  thread_block();
+  intr_set_level(old_level);
+}
+
+static struct thread* thr(struct list_elem* l) {
+  return list_entry(l, struct thread, elem);
+}
+
+void
+thread_unsleep() {
+  const uint64_t ticks = timer_ticks();
+  enum intr_level old_level = intr_disable();
+  if (!list_empty(&sleeping)) {
+
+    struct list_elem* t = list_begin(&sleeping);
+    while (thr(t)->wakeup <= ticks) {
+      // printf("sleeping remove %X\n", thr(t));
+      struct thread* s = thr(t);
+      t = list_remove(t);
+      thread_unblock(s);
+    }
+  }
+  intr_set_level(old_level);
 }
 
 /* Starts preemptive thread scheduling by enabling interrupts.

pintos-env/pintos/threads/thread.h

@@ -1,3 +1,6 @@
+// Author: Claudio Maggioni
+// Author: Tommaso Rodolfo Masera
+
 #ifndef THREADS_THREAD_H
 #define THREADS_THREAD_H
 
@@ -89,7 +92,7 @@ struct thread
     uint8_t *stack;                     /* Saved stack pointer. */
     int priority;                       /* Priority. */
     struct list_elem allelem;           /* List element for all threads list. */
-
+    uint64_t wakeup;
     /* Shared between thread.c and synch.c. */
     struct list_elem elem;              /* List element. */
 
@@ -126,6 +129,9 @@ const char *thread_name (void);
 void thread_exit (void) NO_RETURN;
 void thread_yield (void);
 
+void thread_sleep(uint64_t ticks);
+void thread_unsleep(void);
+
 /* Performs some operation on thread t, given auxiliary data AUX. */
 typedef void thread_action_func (struct thread *t, void *aux);
 void thread_foreach (thread_action_func *, void *);