src/mem/cache/miss/mshr_queue.hh - public/gem5 - Git at Google

 /*
  * Copyright (c) 2003-2005 The Regents of The University of Michigan
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met: redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer;
  * redistributions in binary form must reproduce the above copyright
  * notice, this list of conditions and the following disclaimer in the
  * documentation and/or other materials provided with the distribution;
  * neither the name of the copyright holders nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * Authors: Erik Hallnor
  */

 /** @file
  * Declaration of a structure to manage MSHRs.
  */

 #ifndef __MSHR_QUEUE_HH__
 #define __MSHR_QUEUE_HH__

 #include <vector>
 #include "mem/cache/miss/mshr.hh"

 /**
  * A Class for maintaining a list of pending and allocated memory pktuests.
  */
 class MSHRQueue {
   private:
     /**  MSHR storage. */
     MSHR* registers;
     /** Holds pointers to all allocated MSHRs. */
     MSHR::List allocatedList;
     /** Holds pointers to MSHRs that haven't been sent to the bus. */
     MSHR::List pendingList;
     /** Holds non allocated MSHRs. */
     MSHR::List freeList;

     // Parameters
     /**
      * The total number of MSHRs in this queue. This number is set as the
      * number of MSHRs pktuested plus (numReserve - 1). This allows for
      * the same number of effective MSHRs while still maintaining the reserve.
      */
     const int numMSHRs;

     /**
      * The number of MSHRs to hold in reserve. This is needed because copy
      * operations can allocate upto 4 MSHRs at one time.
      */
     const int numReserve;

   public:
     /** The number of allocated MSHRs. */
     int allocated;
     /** The number of MSHRs that have been forwarded to the bus. */
     int inServiceMSHRs;
     /** The number of targets waiting for response. */
     int allocatedTargets;

     /**
      * Create a queue with a given number of MSHRs.
      * @param num_mshrs The number of MSHRs in this queue.
      * @param reserve The minimum number of MSHRs needed to satisfy any access.
      */
     MSHRQueue(int num_mshrs, int reserve = 1);

     /** Destructor */
     ~MSHRQueue();

     /**
      * Find the first MSHR that matches the provide address and asid.
      * @param addr The address to find.
      * @param asid The address space id.
      * @return Pointer to the matching MSHR, null if not found.
      */
     MSHR* findMatch(Addr addr, int asid) const;

     /**
      * Find and return all the matching MSHRs in the provided vector.
      * @param addr The address to find.
      * @param asid The address space ID.
      * @param matches The vector to return pointers to the matching MSHRs.
      * @return True if any matches are found, false otherwise.
      * @todo Typedef the vector??
      */
     bool findMatches(Addr addr, int asid, std::vector<MSHR*>& matches) const;

     /**
      * Find any pending pktuests that overlap the given request.
      * @param pkt The request to find.
      * @return A pointer to the earliest matching MSHR.
      */
     MSHR* findPending(Packet * &pkt) const;

     /**
      * Allocates a new MSHR for the pktuest and size. This places the request
      * as the first target in the MSHR.
      * @param pkt The request to handle.
      * @param size The number in bytes to fetch from memory.
      * @return The a pointer to the MSHR allocated.
      *
      * @pre There are free MSHRs.
      */
     MSHR* allocate(Packet * &pkt, int size = 0);

     /**
      * Allocate a read pktuest for the given address, and places the given
      * target on the target list.
      * @param addr The address to fetch.
      * @param asid The address space for the fetch.
      * @param size The number of bytes to pktuest.
      * @param target The first target for the pktuest.
      * @return Pointer to the new MSHR.
      */
     MSHR* allocateFetch(Addr addr, int asid, int size, Packet * &target);

     /**
      * Allocate a target list for the given address.
      * @param addr The address to fetch.
      * @param asid The address space for the fetch.
      * @param size The number of bytes to pktuest.
      * @return Pointer to the new MSHR.
      */
     MSHR* allocateTargetList(Addr addr, int asid, int size);

     /**
      * Removes the given MSHR from the queue. This places the MSHR on the
      * free list.
      * @param mshr
      */
     void deallocate(MSHR* mshr);

     /**
      * Allocates a target to the given MSHR. Used to keep track of the number
      * of outstanding targets.
      * @param mshr The MSHR to allocate the target to.
      * @param pkt The target request.
      */
     void allocateTarget(MSHR* mshr, Packet * &pkt)
     {
         mshr->allocateTarget(pkt);
         allocatedTargets += 1;
     }

     /**
      * Remove a MSHR from the queue. Returns an iterator into the allocatedList
      * for faster squash implementation.
      * @param mshr The MSHR to remove.
      * @return An iterator to the next entry in the allocatedList.
      */
     MSHR::Iterator deallocateOne(MSHR* mshr);

     /**
      * Moves the MSHR to the front of the pending list if it is not in service.
      * @param mshr The mshr to move.
      */
     void moveToFront(MSHR *mshr);

     /**
      * Mark the given MSHR as in service. This removes the MSHR from the
      * pendingList. Deallocates the MSHR if it does not expect a response.
      * @param mshr The MSHR to mark in service.
      */
     void markInService(MSHR* mshr);

     /**
      * Mark an in service mshr as pending, used to resend a pktuest.
      * @param mshr The MSHR to resend.
      * @param cmd The command to resend.
      */
     void markPending(MSHR* mshr, Packet::Command cmd);

     /**
      * Squash outstanding pktuests with the given thread number. If a request
      * is in service, just squashes the targets.
      * @param threadNum The thread to squash.
      */
     void squash(int threadNum);

     /**
      * Returns true if the pending list is not empty.
      * @return True if there are outstanding pktuests.
      */
     bool havePending() const
     {
         return !pendingList.empty();
     }

     /**
      * Returns true if there are no free MSHRs.
      * @return True if this queue is full.
      */
     bool isFull() const
     {
         return (allocated > numMSHRs - numReserve);
     }

     /**
      * Returns the pktuest at the head of the pendingList.
      * @return The next pktuest to service.
      */
     Packet * getReq() const
     {
         if (pendingList.empty()) {
             return NULL;
         }
         MSHR* mshr = pendingList.front();
         return mshr->pkt;
     }

     /**
      * Returns the number of outstanding targets.
      * @return the number of allocated targets.
      */
     int getAllocatedTargets() const
     {
         return allocatedTargets;
     }

 };

 #endif //__MSHR_QUEUE_HH__
	/*
	* Copyright (c) 2003-2005 The Regents of The University of Michigan
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are
	* met: redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer;
	* redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution;
	* neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	* Authors: Erik Hallnor
	*/

	/** @file
	* Declaration of a structure to manage MSHRs.
	*/

	#ifndef __MSHR_QUEUE_HH__
	#define __MSHR_QUEUE_HH__

	#include <vector>
	#include "mem/cache/miss/mshr.hh"

	/**
	* A Class for maintaining a list of pending and allocated memory pktuests.
	*/
	class MSHRQueue {
	private:
	/** MSHR storage. */
	MSHR* registers;
	/** Holds pointers to all allocated MSHRs. */
	MSHR::List allocatedList;
	/** Holds pointers to MSHRs that haven't been sent to the bus. */
	MSHR::List pendingList;
	/** Holds non allocated MSHRs. */
	MSHR::List freeList;

	// Parameters
	/**
	* The total number of MSHRs in this queue. This number is set as the
	* number of MSHRs pktuested plus (numReserve - 1). This allows for
	* the same number of effective MSHRs while still maintaining the reserve.
	*/
	const int numMSHRs;

	/**
	* The number of MSHRs to hold in reserve. This is needed because copy
	* operations can allocate upto 4 MSHRs at one time.
	*/
	const int numReserve;

	public:
	/** The number of allocated MSHRs. */
	int allocated;
	/** The number of MSHRs that have been forwarded to the bus. */
	int inServiceMSHRs;
	/** The number of targets waiting for response. */
	int allocatedTargets;

	/**
	* Create a queue with a given number of MSHRs.
	* @param num_mshrs The number of MSHRs in this queue.
	* @param reserve The minimum number of MSHRs needed to satisfy any access.
	*/
	MSHRQueue(int num_mshrs, int reserve = 1);

	/** Destructor */
	~MSHRQueue();

	/**
	* Find the first MSHR that matches the provide address and asid.
	* @param addr The address to find.
	* @param asid The address space id.
	* @return Pointer to the matching MSHR, null if not found.
	*/
	MSHR* findMatch(Addr addr, int asid) const;

	/**
	* Find and return all the matching MSHRs in the provided vector.
	* @param addr The address to find.
	* @param asid The address space ID.
	* @param matches The vector to return pointers to the matching MSHRs.
	* @return True if any matches are found, false otherwise.
	* @todo Typedef the vector??
	*/
	bool findMatches(Addr addr, int asid, std::vector<MSHR*>& matches) const;

	/**
	* Find any pending pktuests that overlap the given request.
	* @param pkt The request to find.
	* @return A pointer to the earliest matching MSHR.
	*/
	MSHR* findPending(Packet * &pkt) const;

	/**
	* Allocates a new MSHR for the pktuest and size. This places the request
	* as the first target in the MSHR.
	* @param pkt The request to handle.
	* @param size The number in bytes to fetch from memory.
	* @return The a pointer to the MSHR allocated.
	*
	* @pre There are free MSHRs.
	*/
	MSHR* allocate(Packet * &pkt, int size = 0);

	/**
	* Allocate a read pktuest for the given address, and places the given
	* target on the target list.
	* @param addr The address to fetch.
	* @param asid The address space for the fetch.
	* @param size The number of bytes to pktuest.
	* @param target The first target for the pktuest.
	* @return Pointer to the new MSHR.
	*/
	MSHR* allocateFetch(Addr addr, int asid, int size, Packet * &target);

	/**
	* Allocate a target list for the given address.
	* @param addr The address to fetch.
	* @param asid The address space for the fetch.
	* @param size The number of bytes to pktuest.
	* @return Pointer to the new MSHR.
	*/
	MSHR* allocateTargetList(Addr addr, int asid, int size);

	/**
	* Removes the given MSHR from the queue. This places the MSHR on the
	* free list.
	* @param mshr
	*/
	void deallocate(MSHR* mshr);

	/**
	* Allocates a target to the given MSHR. Used to keep track of the number
	* of outstanding targets.
	* @param mshr The MSHR to allocate the target to.
	* @param pkt The target request.
	*/
	void allocateTarget(MSHR* mshr, Packet * &pkt)
	{
	mshr->allocateTarget(pkt);
	allocatedTargets += 1;
	}

	/**
	* Remove a MSHR from the queue. Returns an iterator into the allocatedList
	* for faster squash implementation.
	* @param mshr The MSHR to remove.
	* @return An iterator to the next entry in the allocatedList.
	*/
	MSHR::Iterator deallocateOne(MSHR* mshr);

	/**
	* Moves the MSHR to the front of the pending list if it is not in service.
	* @param mshr The mshr to move.
	*/
	void moveToFront(MSHR *mshr);

	/**
	* Mark the given MSHR as in service. This removes the MSHR from the
	* pendingList. Deallocates the MSHR if it does not expect a response.
	* @param mshr The MSHR to mark in service.
	*/
	void markInService(MSHR* mshr);

	/**
	* Mark an in service mshr as pending, used to resend a pktuest.
	* @param mshr The MSHR to resend.
	* @param cmd The command to resend.
	*/
	void markPending(MSHR* mshr, Packet::Command cmd);

	/**
	* Squash outstanding pktuests with the given thread number. If a request
	* is in service, just squashes the targets.
	* @param threadNum The thread to squash.
	*/
	void squash(int threadNum);

	/**
	* Returns true if the pending list is not empty.
	* @return True if there are outstanding pktuests.
	*/
	bool havePending() const
	{
	return !pendingList.empty();
	}

	/**
	* Returns true if there are no free MSHRs.
	* @return True if this queue is full.
	*/
	bool isFull() const
	{
	return (allocated > numMSHRs - numReserve);
	}

	/**
	* Returns the pktuest at the head of the pendingList.
	* @return The next pktuest to service.
	*/
	Packet * getReq() const
	{
	if (pendingList.empty()) {
	return NULL;
	}
	MSHR* mshr = pendingList.front();
	return mshr->pkt;
	}

	/**
	* Returns the number of outstanding targets.
	* @return the number of allocated targets.
	*/
	int getAllocatedTargets() const
	{
	return allocatedTargets;
	}

	};

	#endif //__MSHR_QUEUE_HH__