scheduler.h

Nachos 线程

// scheduler.h 
//	Data structures for the thread dispatcher and scheduler.
//	Primarily, the list of threads that are ready to run.
//
// Copyright (c) 1992-1993 The Regents of the University of California.
// All rights reserved.  See copyright.h for copyright notice and limitation 
// of liability and disclaimer of warranty provisions.

#ifndef SCHEDULER_H
#define SCHEDULER_H

#include "copyright.h"
#include "list.h"
#include "thread.h"
#include "timer.h"

enum SchedPolicy { 
  SCHED_FCFS,     // 5.3.1 First-come first-served scheduling (MP1)
    SCHED_SJF,    // 5.3.2 Shortest job first scheduling 
    SCHED_PRIO_NP,// 5.3.3 Nonpreemptive Priority scheduling (MP1)
    SCHED_PRIO_P, // 5.3.3 Preemptive     Priority scheduling (MP1)
    SCHED_RR,     // 5.3.4 Round robin scheduling (MP1)
    SCHED_MLQ,    // 5.3.5 Multilevel queue scheduling (MP1)
    SCHED_MLFQ    // 5.3.6 Multilevel feedback queue scheduling
};
		     

// The following class defines the scheduler/dispatcher abstraction -- 
// the data structures and operations needed to keep track of which 
// thread is running, and which threads are ready but not running.

class Scheduler {
  public:
    Scheduler();		        // Initialize list of ready threads 
    ~Scheduler();			// De-allocate ready list

    void ReadyToRun(Thread* thread);	// Thread can be dispatched.
    Thread* FindNextToRun();		// Dequeue first thread on the ready 
					// list, if any, and return thread.
    bool ShouldISwitch(Thread* oldThread, Thread* newThread);
    void Run(Thread* nextThread);	// Cause nextThread to start running
    void Print();			// Print contents of ready list
    void Suspend(Thread *thread);
    void Resume(Thread *thread);
    void SetSchedPolicy(SchedPolicy pol); 
    void SetNumOfQueues(int level);   // set the number of queues for MLQ
    void InterruptHandler( int dummy );

  private:
    SchedPolicy policy;            // scheduling policy to be used
    List<Thread *> *readyList; 	   // queue of threads that are ready to run,
				   // but not running
    List<Thread *> *suspendedList; // List of suspended threads.
    Timer * ptimer;                // A timer, if needed.
};

#endif // SCHEDULER_H