1 #ifndef THREADS_THREAD_H
2 #define THREADS_THREAD_H
8 /* States in a thread's life cycle. */
11 THREAD_RUNNING, /* Running thread. */
12 THREAD_READY, /* Not running but ready to run. */
13 THREAD_BLOCKED, /* Waiting for an event to trigger. */
14 THREAD_DYING /* About to be destroyed. */
17 /* Thread identifier type.
18 You can redefine this to whatever type you like. */
20 #define TID_ERROR ((tid_t) -1) /* Error value for tid_t. */
22 /* Thread priorities. */
23 #define PRI_MIN 0 /* Lowest priority. */
24 #define PRI_DEFAULT 31 /* Default priority. */
25 #define PRI_MAX 63 /* Highest priority. */
27 /* A kernel thread or user process.
29 Each thread structure is stored in its own 4 kB page. The
30 thread structure itself sits at the very bottom of the page
31 (at offset 0). The rest of the page is reserved for the
32 thread's kernel stack, which grows downward from the top of
33 the page (at offset 4 kB). Here's an illustration:
35 4 kB +---------------------------------+
49 +---------------------------------+
55 0 kB +---------------------------------+
57 The upshot of this is twofold:
59 1. First, `struct thread' must not be allowed to grow too
60 big. If it does, then there will not be enough room for
61 the kernel stack. Our base `struct thread' is only a
62 few bytes in size. It probably should stay well under 1
65 2. Second, kernel stacks must not be allowed to grow too
66 large. If a stack overflows, it will corrupt the thread
67 state. Thus, kernel functions should not allocate large
68 structures or arrays as non-static local variables. Use
69 dynamic allocation with malloc() or palloc_get_page()
72 The first symptom of either of these problems will probably be
73 an assertion failure in thread_current(), which checks that
74 the `magic' member of the running thread's `struct thread' is
75 set to THREAD_MAGIC. Stack overflow will normally change this
76 value, triggering the assertion. */
77 /* The `elem' member has a dual purpose. It can be an element in
78 the run queue (thread.c), or it can be an element in a
79 semaphore wait list (synch.c). It can be used these two ways
80 only because they are mutually exclusive: only a thread in the
81 ready state is on the run queue, whereas only a thread in the
82 blocked state is on a semaphore wait list. */
85 /* Owned by thread.c. */
86 tid_t tid; /* Thread identifier. */
87 enum thread_status status; /* Thread state. */
88 char name[16]; /* Name (for debugging purposes). */
89 uint8_t *stack; /* Saved stack pointer. */
90 int priority; /* Priority. */
91 struct list_elem allelem; /* List element for all threads list. */
93 /* Shared between thread.c and synch.c. */
94 struct list_elem elem; /* List element. */
97 /* Owned by userprog/process.c. */
98 uint32_t *pagedir; /* Page directory. */
101 /* Owned by thread.c. */
102 unsigned magic; /* Detects stack overflow. */
105 /* If false (default), use round-robin scheduler.
106 If true, use multi-level feedback queue scheduler.
107 Controlled by kernel command-line option "-o mlfqs". */
108 extern bool thread_mlfqs;
110 void thread_init (void);
111 void thread_start (void);
113 void thread_tick (void);
114 void thread_print_stats (void);
116 typedef void thread_func (void *aux);
117 tid_t thread_create (const char *name, int priority, thread_func *, void *);
119 void thread_block (void);
120 void thread_unblock (struct thread *);
122 struct thread *thread_current (void);
123 tid_t thread_tid (void);
124 const char *thread_name (void);
126 void thread_exit (void) NO_RETURN;
127 void thread_yield (void);
129 /* Performs some operation on thread t, given auxiliary data AUX. */
130 typedef void thread_action_func (struct thread *t, void *aux);
131 void thread_foreach (thread_action_func *, void *);
133 int thread_get_priority (void);
134 void thread_set_priority (int);
136 int thread_get_nice (void);
137 void thread_set_nice (int);
138 int thread_get_recent_cpu (void);
139 int thread_get_load_avg (void);
141 #endif /* threads/thread.h */