#include <debug.h>
#include <stddef.h>
#include <random.h>
+#include <stdio.h>
#include <string.h>
+#include "threads/flags.h"
#include "threads/interrupt.h"
#include "threads/intr-stubs.h"
#include "threads/mmu.h"
#include "threads/palloc.h"
#include "threads/switch.h"
+#include "threads/synch.h"
#ifdef USERPROG
+#include "userprog/addrspace.h"
#include "userprog/gdt.h"
#endif
-/* Value for struct thread's `magic' member.
+/* Random value for struct thread's `magic' member.
Used to detect stack overflow. See the big comment at the top
of thread.h for details. */
-#define THREAD_MAGIC 0x1234abcdu
+#define THREAD_MAGIC 0xcd6abf4b
/* List of processes in THREAD_READY state, that is, processes
that are ready to run but not actually running. */
-static struct list run_queue;
+static struct list ready_list;
/* Idle thread. */
-static struct thread *idle_thread; /* Thread. */
-static void idle (void *aux UNUSED); /* Thread function. */
+static struct thread *idle_thread;
+
+/* Initial thread, the thread running init.c:main(). */
+static struct thread *initial_thread;
+
+/* Lock used by allocate_tid(). */
+static struct lock tid_lock;
/* Stack frame for kernel_thread(). */
struct kernel_thread_frame
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);
-static void init_thread (struct thread *, const char *name);
+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
void
thread_init (void)
{
- struct thread *t;
-
ASSERT (intr_get_level () == INTR_OFF);
+ lock_init (&tid_lock, "tid");
+
/* Set up a thread structure for the running thread. */
- t = running_thread ();
- init_thread (t, "main");
- t->status = THREAD_RUNNING;
+ 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 (&run_queue);
+ list_init (&ready_list);
}
/* Starts preemptive thread scheduling by enabling interrupts.
void
thread_start (void)
{
- /* Create idle thread. */
- idle_thread = thread_create ("idle", idle, NULL);
- idle_thread->status = THREAD_BLOCKED;
-
- /* Enable interrupts. */
+ thread_create ("idle", PRI_DEFAULT, idle, NULL);
intr_enable ();
}
-/* Creates a new kernel thread named NAME, 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. Use a
- semaphore or some other form of synchronization if you need to
- ensure ordering. */
-struct thread *
-thread_create (const char *name, thread_func *function, void *aux)
+/* 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.
+
+ The code provided sets the new thread's `priority' member to
+ PRIORITY, but no actual priority scheduling is implemented.
+ Priority scheduling is the goal of Problem 1-3. */
+tid_t
+thread_create (const char *name, int priority,
+ thread_func *function, void *aux)
{
struct thread *t;
struct kernel_thread_frame *kf;
struct switch_entry_frame *ef;
struct switch_threads_frame *sf;
+ tid_t tid;
ASSERT (function != NULL);
- t = new_thread (name);
+ t = new_thread (name, priority);
+ if (t == NULL)
+ return TID_ERROR;
+ tid = t->tid;
/* Stack frame for kernel_thread(). */
kf = alloc_frame (t, sizeof *kf);
/* Add to run queue. */
thread_unblock (t);
- return t;
-}
-
-#ifdef USERPROG
-/* Starts a new thread running a user program loaded from
- FILENAME, and adds it to the ready queue. If thread_start()
- has been called, then new thread may be scheduled before
- thread_execute() returns.*/
-bool
-thread_execute (const char *filename)
-{
- struct thread *t;
- struct intr_frame *if_;
- struct switch_entry_frame *ef;
- struct switch_threads_frame *sf;
- void (*start) (void);
-
- ASSERT (filename != NULL);
-
- t = new_thread (filename);
- if (t == NULL)
- return false;
-
- if (!addrspace_load (t, filename, &start))
- PANIC ("%s: program load failed", filename);
-
- /* Interrupt frame. */
- if_ = alloc_frame (t, sizeof *if_);
- if_->es = SEL_UDSEG;
- if_->ds = SEL_UDSEG;
- if_->eip = start;
- if_->cs = SEL_UCSEG;
- if_->eflags = FLAG_IF | FLAG_MBS;
- if_->esp = PHYS_BASE;
- if_->ss = SEL_UDSEG;
-
- /* Stack frame for switch_entry(). */
- ef = alloc_frame (t, sizeof *ef);
- ef->eip = intr_exit;
-
- /* Stack frame for switch_threads(). */
- sf = alloc_frame (t, sizeof *sf);
- sf->eip = switch_entry;
-
- /* Add to run queue. */
- thread_unblock (t);
-
- return true;
+ return tid;
}
-#endif
/* Transitions a blocked thread T from its current state to the
- ready-to-run state. If T is not blocked, there is no effect.
+ 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)
ASSERT (is_thread (t));
old_level = intr_disable ();
- if (t->status == THREAD_BLOCKED)
- {
- list_push_back (&run_queue, &t->elem);
- t->status = THREAD_READY;
- }
+ ASSERT (t->status == THREAD_BLOCKED);
+ list_push_back (&ready_list, &t->elem);
+ t->status = THREAD_READY;
intr_set_level (old_level);
}
-/* Returns the name of thread T. */
+/* Returns the name of the running thread. */
const char *
-thread_name (struct thread *t)
+thread_name (void)
{
- ASSERT (is_thread (t));
- return t->name;
+ return thread_current ()->name;
}
/* Returns the running thread.
return t;
}
+/* Returns the running thread's tid. */
+tid_t
+thread_tid (void)
+{
+ return thread_current ()->tid;
+}
+
/* Deschedules the current thread and destroys it. Never
returns to the caller. */
void
ASSERT (!intr_context ());
old_level = intr_disable ();
- list_push_back (&run_queue, &cur->elem);
+ list_push_back (&ready_list, &cur->elem);
cur->status = THREAD_READY;
schedule ();
intr_set_level (old_level);
static void
idle (void *aux UNUSED)
{
+ idle_thread = thread_current ();
+
for (;;)
{
- /* Wait for an interrupt. */
- DEBUG (idle, "idle");
- asm ("hlt");
-
/* Let someone else run. */
intr_disable ();
thread_block ();
intr_enable ();
+
+ /* Use CPU `hlt' instruction to wait for interrupt. */
+ asm ("hlt");
}
}
return t != NULL && t->magic == THREAD_MAGIC;
}
-/* Creates a new thread named NAME and initializes its fields.
- Returns the new thread if successful or a null pointer on
- failure. */
+/* 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)
+new_thread (const char *name, int priority)
{
- struct thread *t;
-
- ASSERT (name != NULL);
-
- t = palloc_get (PAL_ZERO);
- if (t != NULL)
- init_thread (t, name);
+ struct thread *t = palloc_get (PAL_ZERO);
+ if (t != NULL)
+ {
+ init_thread (t, name, priority);
+ t->tid = allocate_tid ();
+ }
return t;
}
-/* Initializes T as a new, blocked thread named NAME. */
+/* Does basic initialization of T as a blocked thread named
+ NAME. */
static void
-init_thread (struct thread *t, const char *name)
+init_thread (struct thread *t, const char *name, int priority)
{
+ ASSERT (t != NULL);
+ ASSERT (PRI_MIN <= priority && priority <= PRI_MAX);
+ ASSERT (name != NULL);
+
memset (t, 0, sizeof *t);
+ t->status = THREAD_BLOCKED;
strlcpy (t->name, name, sizeof t->name);
t->stack = (uint8_t *) t + PGSIZE;
- t->status = THREAD_BLOCKED;
+ t->priority = priority;
t->magic = THREAD_MAGIC;
}
static struct thread *
next_thread_to_run (void)
{
- if (list_empty (&run_queue))
+ if (list_empty (&ready_list))
return idle_thread;
else
- return list_entry (list_pop_front (&run_queue), struct thread, elem);
+ return list_entry (list_pop_front (&ready_list), struct thread, elem);
}
-/* Destroys T, which must be in the dying state and must not be
- the running thread. */
+/* Destroys T, which must not be the running thread. */
static void
destroy_thread (struct thread *t)
{
ASSERT (is_thread (t));
- ASSERT (t->status == THREAD_DYING);
ASSERT (t != thread_current ());
#ifdef USERPROG
addrspace_destroy (t);
#endif
- palloc_free (t);
+ if (t != initial_thread)
+ palloc_free (t);
}
/* Completes a thread switch by activating the new thread's page
#ifdef USERPROG
/* Activate the new address space. */
- addrspace_activate (cur);
+ addrspace_activate ();
#endif
/* If the thread we switched from is dying, destroy it.
prev = switch_threads (cur, next);
schedule_tail (prev);
}
+
+/* Returns a tid to use for a new thread. */
+static tid_t
+allocate_tid (void)
+{
+ static tid_t next_tid = 1;
+ tid_t tid;
+
+ lock_acquire (&tid_lock);
+ tid = next_tid++;
+ lock_release (&tid_lock);
+
+ return tid;
+}
\f
/* Offset of `stack' member within `struct thread'.
Used by switch.S, which can't figure it out on its own. */
projects / pintos-anon / blobdiff