richards.js.svn-base

Google浏览器V8内核代码

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// This is a JavaScript implementation of the Richards
// benchmark from:
//
//    http://www.cl.cam.ac.uk/~mr10/Bench.html
// 
// The benchmark was originally implemented in BCPL by
// Martin Richards.


var Richards = new BenchmarkSuite('Richards', 34886, [
  new Benchmark("Richards", runRichards)
]);


/**
 * The Richards benchmark simulates the task dispatcher of an
 * operating system.
 **/
function runRichards() {
  var scheduler = new Scheduler();
  scheduler.addIdleTask(ID_IDLE, 0, null, COUNT);

  var queue = new Packet(null, ID_WORKER, KIND_WORK);
  queue = new Packet(queue,  ID_WORKER, KIND_WORK);
  scheduler.addWorkerTask(ID_WORKER, 1000, queue);

  queue = new Packet(null, ID_DEVICE_A, KIND_DEVICE);
  queue = new Packet(queue,  ID_DEVICE_A, KIND_DEVICE);
  queue = new Packet(queue,  ID_DEVICE_A, KIND_DEVICE);
  scheduler.addHandlerTask(ID_HANDLER_A, 2000, queue);

  queue = new Packet(null, ID_DEVICE_B, KIND_DEVICE);
  queue = new Packet(queue,  ID_DEVICE_B, KIND_DEVICE);
  queue = new Packet(queue,  ID_DEVICE_B, KIND_DEVICE);
  scheduler.addHandlerTask(ID_HANDLER_B, 3000, queue);

  scheduler.addDeviceTask(ID_DEVICE_A, 4000, null);

  scheduler.addDeviceTask(ID_DEVICE_B, 5000, null);

  scheduler.schedule();

  if (scheduler.queueCount != EXPECTED_QUEUE_COUNT ||
      scheduler.holdCount != EXPECTED_HOLD_COUNT) {
    var msg =
        "Error during execution: queueCount = " + scheduler.queueCount +
        ", holdCount = " + scheduler.holdCount + ".";
    print(msg);
  }
}

var COUNT = 1000;

/**
 * These two constants specify how many times a packet is queued and
 * how many times a task is put on hold in a correct run of richards.
 * They don't have any meaning a such but are characteristic of a
 * correct run so if the actual queue or hold count is different from
 * the expected there must be a bug in the implementation.
 **/
var EXPECTED_QUEUE_COUNT = 2322;
var EXPECTED_HOLD_COUNT = 928;


/**
 * A scheduler can be used to schedule a set of tasks based on their relative
 * priorities.  Scheduling is done by maintaining a list of task control blocks
 * which holds tasks and the data queue they are processing.
 * @constructor
 */
function Scheduler() {
  this.queueCount = 0;
  this.holdCount = 0;
  this.blocks = new Array(NUMBER_OF_IDS);
  this.list = null;
  this.currentTcb = null;
  this.currentId = null;
}

var ID_IDLE       = 0;
var ID_WORKER     = 1;
var ID_HANDLER_A  = 2;
var ID_HANDLER_B  = 3;
var ID_DEVICE_A   = 4;
var ID_DEVICE_B   = 5;
var NUMBER_OF_IDS = 6;

var KIND_DEVICE   = 0;
var KIND_WORK     = 1;

/**
 * Add an idle task to this scheduler.
 * @param {int} id the identity of the task
 * @param {int} priority the task's priority
 * @param {Packet} queue the queue of work to be processed by the task
 * @param {int} count the number of times to schedule the task
 */
Scheduler.prototype.addIdleTask = function (id, priority, queue, count) {
  this.addRunningTask(id, priority, queue, new IdleTask(this, 1, count));
};

/**
 * Add a work task to this scheduler.
 * @param {int} id the identity of the task
 * @param {int} priority the task's priority
 * @param {Packet} queue the queue of work to be processed by the task
 */
Scheduler.prototype.addWorkerTask = function (id, priority, queue) {
  this.addTask(id, priority, queue, new WorkerTask(this, ID_HANDLER_A, 0));
};

/**
 * Add a handler task to this scheduler.
 * @param {int} id the identity of the task
 * @param {int} priority the task's priority
 * @param {Packet} queue the queue of work to be processed by the task
 */
Scheduler.prototype.addHandlerTask = function (id, priority, queue) {
  this.addTask(id, priority, queue, new HandlerTask(this));
};

/**
 * Add a handler task to this scheduler.
 * @param {int} id the identity of the task
 * @param {int} priority the task's priority
 * @param {Packet} queue the queue of work to be processed by the task
 */
Scheduler.prototype.addDeviceTask = function (id, priority, queue) {
  this.addTask(id, priority, queue, new DeviceTask(this))
};

/**
 * Add the specified task and mark it as running.
 * @param {int} id the identity of the task
 * @param {int} priority the task's priority
 * @param {Packet} queue the queue of work to be processed by the task
 * @param {Task} task the task to add
 */
Scheduler.prototype.addRunningTask = function (id, priority, queue, task) {
  this.addTask(id, priority, queue, task);
  this.currentTcb.setRunning();
};

/**
 * Add the specified task to this scheduler.
 * @param {int} id the identity of the task
 * @param {int} priority the task's priority
 * @param {Packet} queue the queue of work to be processed by the task
 * @param {Task} task the task to add
 */
Scheduler.prototype.addTask = function (id, priority, queue, task) {
  this.currentTcb = new TaskControlBlock(this.list, id, priority, queue, task);
  this.list = this.currentTcb;
  this.blocks[id] = this.currentTcb;
};

/**
 * Execute the tasks managed by this scheduler.
 */
Scheduler.prototype.schedule = function () {
  this.currentTcb = this.list;
  while (this.currentTcb != null) {
    if (this.currentTcb.isHeldOrSuspended()) {
      this.currentTcb = this.currentTcb.link;
    } else {
      this.currentId = this.currentTcb.id;
      this.currentTcb = this.currentTcb.run();
    }
  }
};

/**
 * Release a task that is currently blocked and return the next block to run.
 * @param {int} id the id of the task to suspend
 */
Scheduler.prototype.release = function (id) {
  var tcb = this.blocks[id];
  if (tcb == null) return tcb;
  tcb.markAsNotHeld();
  if (tcb.priority > this.currentTcb.priority) {
    return tcb;
  } else {
    return this.currentTcb;
  }
};

/**
 * Block the currently executing task and return the next task control block
 * to run.  The blocked task will not be made runnable until it is explicitly
 * released, even if new work is added to it.
 */
Scheduler.prototype.holdCurrent = function () {
  this.holdCount++;
  this.currentTcb.markAsHeld();
  return this.currentTcb.link;
};

/**
 * Suspend the currently executing task and return the next task control block
 * to run.  If new work is added to the suspended task it will be made runnable.
 */
Scheduler.prototype.suspendCurrent = function () {
  this.currentTcb.markAsSuspended();
  return this.currentTcb;
};

/**
 * Add the specified packet to the end of the worklist used by the task
 * associated with the packet and make the task runnable if it is currently
 * suspended.
 * @param {Packet} packet the packet to add
 */
Scheduler.prototype.queue = function (packet) {
  var t = this.blocks[packet.id];
  if (t == null) return t;
  this.queueCount++;
  packet.link = null;
  packet.id = this.currentId;
  return t.checkPriorityAdd(this.currentTcb, packet);
};

/**
 * A task control block manages a task and the queue of work packages associated
 * with it.
 * @param {TaskControlBlock} link the preceding block in the linked block list
 * @param {int} id the id of this block
 * @param {int} priority the priority of this block
 * @param {Packet} queue the queue of packages to be processed by the task
 * @param {Task} task the task
 * @constructor
 */
function TaskControlBlock(link, id, priority, queue, task) {
  this.link = link;
  this.id = id;
  this.priority = priority;
  this.queue = queue;
  this.task = task;
  if (queue == null) {
    this.state = STATE_SUSPENDED;
  } else {
    this.state = STATE_SUSPENDED_RUNNABLE;
  }