pass proj1

lecture_note/docs/pintos/proj1.md

@@ -250,7 +250,7 @@ TA 拿锁 B, TA 捐赠给 B, B 捐赠给 TB, interrupt
 TB 拿锁 A, TB 捐赠给 A, A 捐赠给 TA, TA 捐赠给 B...
 ```
 
-解决?方式: 对于嵌套优先级捐赠关系的环 (From document "If necessary, you may impose a reasonable limit on depth of nested priority donation, such as 8 levels."), 加一个传递层数即可.
+解决?方式: 对于嵌套优先级捐赠关系的环 (From document "If necessary, you may impose a reasonable limit on depth of nested priority donation, such as 8 levels."), 加一个传递层数?.
 
 外界死锁实在没法解决, 但是属于 UB, 不解决也行. 可以考虑加一个检查是否所有的线程都被 block, 如果如此就立一个 flag 清除所有的线程, 然后 PANIC.
 
@@ -262,7 +262,7 @@ TB 拿锁 A, TB 捐赠给 A, A 捐赠给 TA, TA 捐赠给 B...
 
 问题: 被更新 priority 的 thread 还在堆 / ready_list 里面, 但是插入已经发生了, 该 heap_up / heap_down?
 
-解决?方式: 不管, 下一次进堆的时候就好了.
+解决?方式: 在完成从叶子节点到根节点的 donation 之后, 禁用中断然后 $O(n)$ 建堆.
 
 ## Task 3
 
@@ -272,4 +272,33 @@ TB 拿锁 A, TB 捐赠给 A, A 捐赠给 TA, TA 捐赠给 B...
 
 在 pintos 内核中没有浮点数运算, 需要手动实现定点数来完成 `load_avg`, `nice` 等 MLFQS 相关值的计算.
 
-使用 32 位 `int` 保存一个定点数, 令 `x` 表示实数 `x / (2^14)`, 即使用最低 14 位存储分数.
+使用 32 位 `int` 保存一个定点数, 令 `x` 表示实数 `x / (2^14)`, 即使用最低 14 位存储分数.
+
+
+### 更改 nice
+
+nice 只来自外界传入 / 从 parent thread 继承, 修改后更新优先级即可.
+
+### 计算 priority
+
+$$
+priority = PRI_MAX - \dfrac{1}{4} recent_cpu - 2 \cdot nice
+$$
+
+需要控制范围不超过 `PRI_MIN` 到 `PRI_MAX`.
+
+### 计算 recent_cpu
+
+$$
+recent_cpu = \dfrac{2 \cdot load_avg}{2 \cdot load_avg + 1} \cdor recent_cpu + nice
+$$
+
+### 计算 load_avg
+
+`load_avg` 是全局的, 不是某个线程的属性.
+
+$$
+load_avg = \dfrac{59}{60} load_avg + \dfrac{1}{60} ready_thread
+$$
+
+$ready_thread$ 代表正在运行/就绪的线程数量.

pintos/src/Makefile.build

@@ -21,7 +21,6 @@ threads_SRC += threads/intr-stubs.S	 # Interrupt stubs.
 threads_SRC += threads/synch.c		 # Synchronization.
 threads_SRC += threads/palloc.c	 	 # Page allocator.
 threads_SRC += threads/malloc.c	     # Subpage allocator.
-threads_SRC += threads/fixed-point.c # Fixed-Point real arithmetic.
 
 # Device driver code.
 devices_SRC  = devices/pit.c		# Programmable interrupt timer chip.

pintos/src/lib/kernel/heap.c

@@ -20,6 +20,15 @@ heap_init (struct heap *heap, heap_less_func *less)
   heap->push_cnt = 0;
 }
 
+/* Rebuild heap */
+void
+heap_rebuild (struct heap *heap)
+{
+  ASSERT (heap != NULL);
+  for (size_t i = heap->size; i > 0; i--)
+    down_heap (heap, i);
+}
+
 heap_elem
 heap_top (struct heap *heap)
 {

pintos/src/lib/kernel/heap.h

@@ -38,6 +38,7 @@ struct heap
 
 /* Heap initialization. */
 void heap_init (struct heap *, heap_less_func *);
+void heap_rebuild (struct heap *);
 
 /* Heap elements. */
 heap_elem heap_top (struct heap *);

pintos/src/threads/fixed-point.h

@@ -2,7 +2,80 @@
 #define THREADS_FIXED_POINT_H
 
 #include <debug.h>
+#include <stdint.h>
 
 typedef int fixed_point;
 
+#define F_BITS 16384
+
+/* Integer to fixed point number */
+static inline fixed_point
+itofp (const int x)
+{
+  return x * F_BITS;
+}
+
+/* Fixed point to integer */
+static inline int
+fptoi (const fixed_point x)
+{
+  return x / F_BITS;
+}
+
+/* Fixed point to integer (round) */
+static inline int
+fptoi_round (const fixed_point x)
+{
+  return x >= 0 ? (x + F_BITS / 2) / F_BITS :
+                  (x - F_BITS / 2) / F_BITS;
+}
+
+static inline fixed_point
+fp_add (const fixed_point a, const fixed_point b)
+{
+  return a + b;
+}
+
+static inline fixed_point
+fp_sub (const fixed_point a, const fixed_point b)
+{
+  return a - b;
+}
+
+static inline fixed_point
+fp_mul (const fixed_point a, const fixed_point b)
+{
+  return ((int64_t)a * b) / F_BITS;
+}
+
+static inline fixed_point
+fp_div (const fixed_point a, const fixed_point b)
+{
+  return ((int64_t)a * F_BITS) / b;
+}
+
+static inline fixed_point
+fp_int_add (const fixed_point a, const int b)
+{
+  return a + b * F_BITS;
+}
+
+static inline fixed_point
+fp_int_sub (const fixed_point a, const int b)
+{
+  return a - b * F_BITS;
+}
+
+static inline fixed_point
+fp_int_mul (const fixed_point a, const int b)
+{
+  return a * b;
+}
+
+static inline fixed_point
+fp_int_div (const fixed_point a, const int b)
+{
+  return a / b;
+}
+
 #endif /* threads/fixed-point.h */

pintos/src/threads/synch.c

@@ -124,7 +124,10 @@ sema_up (struct semaphore *sema)
     }
   sema->value++;
   intr_set_level (old_level);
-  thread_yield ();
+  if (intr_context ())
+    intr_yield_on_return ();
+  else
+    thread_yield ();
 }
 
 static void sema_test_helper (void *sema_);
@@ -213,6 +216,11 @@ lock_acquire (struct lock *lock)
     {
       cur->lock_waiting = lock;
       donate_priority (cur, 0);
+
+      old_level = intr_disable ();
+      sort_ready_heap ();
+      intr_set_level (old_level);
+
       sema_down (&lock->semaphore);
 
       old_level = intr_disable ();
@@ -265,7 +273,7 @@ lock_release (struct lock *lock)
   list_remove (&lock->elem);
 
   intr_set_level (old_level);
-  thread_update_priority (thread_current ());
+  thread_update_priority (thread_current (), NULL);
   sema_up (&lock->semaphore);
 }
 
@@ -274,6 +282,8 @@ lock_release (struct lock *lock)
 void
 donate_priority (struct thread *t, int dep)
 {
+  if (thread_mlfqs)
+    return;
   ASSERT (t != NULL);
 
   if (dep > DONATE_MAX_DEPTH || t->lock_waiting == NULL)