src/mem/packet_queue.hh - public/gem5 - Git at Google

 /*
  * Copyright (c) 2012,2015,2018 ARM Limited
  * All rights reserved.
  *
  * The license below extends only to copyright in the software and shall
  * not be construed as granting a license to any other intellectual
  * property including but not limited to intellectual property relating
  * to a hardware implementation of the functionality of the software
  * licensed hereunder.  You may use the software subject to the license
  * terms below provided that you ensure that this notice is replicated
  * unmodified and in its entirety in all distributions of the software,
  * modified or unmodified, in source code or in binary form.
  *
  * Copyright (c) 2006 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.
  */

 #ifndef __MEM_PACKET_QUEUE_HH__
 #define __MEM_PACKET_QUEUE_HH__

 /**
  * @file
  * Declaration of a simple PacketQueue that is associated with
  * a port on which it attempts to send packets according to the time
  * stamp given to them at insertion. The packet queue is responsible
  * for the flow control of the port.
  */

 #include <list>

 #include "mem/port.hh"
 #include "sim/drain.hh"
 #include "sim/eventq.hh"

 /**
  * A packet queue is a class that holds deferred packets and later
  * sends them using the associated CPU-side port or memory-side port.
  */
 class PacketQueue : public Drainable
 {
   private:
     /** A deferred packet, buffered to transmit later. */
     class DeferredPacket {
       public:
         Tick tick;      ///< The tick when the packet is ready to transmit
         PacketPtr pkt;  ///< Pointer to the packet to transmit
         DeferredPacket(Tick t, PacketPtr p)
             : tick(t), pkt(p)
         {}
     };

     typedef std::list<DeferredPacket> DeferredPacketList;

     /** A list of outgoing packets. */
     DeferredPacketList transmitList;

     /** The manager which is used for the event queue */
     EventManager& em;

     /** Used to schedule sending of deferred packets. */
     void processSendEvent();

     /** Event used to call processSendEvent. */
     EventFunctionWrapper sendEvent;

      /*
       * Optionally disable the sanity check
       * on the size of the transmitList. The
       * sanity check will be enabled by default.
       */
     bool _disableSanityCheck;

     /**
      * if true, inserted packets have to be unconditionally scheduled
      * after the last packet in the queue that references the same
      * address
      */
     bool forceOrder;

   protected:

     /** Label to use for print request packets label stack. */
     const std::string label;

     /** Remember whether we're awaiting a retry. */
     bool waitingOnRetry;

     /** Check whether we have a packet ready to go on the transmit list. */
     bool deferredPacketReady() const
     { return !transmitList.empty() && transmitList.front().tick <= curTick(); }

     /**
      * Attempt to send a packet. Note that a subclass of the
      * PacketQueue can override this method and thus change the
      * behaviour (as done by the cache for the request queue). The
      * default implementation sends the head of the transmit list. The
      * caller must guarantee that the list is non-empty and that the
      * head packet is scheduled for curTick() (or earlier).
      */
     virtual void sendDeferredPacket();

     /**
      * Send a packet using the appropriate method for the specific
      * subclass (request, response or snoop response).
      */
     virtual bool sendTiming(PacketPtr pkt) = 0;

     /**
      * Create a packet queue, linked to an event manager, and a label
      * that will be used for functional print request packets.
      *
      * @param _em Event manager used for scheduling this queue
      * @param _label Label to push on the label stack for print request packets
      * @param force_order Force insertion order for packets with same address
      * @param disable_sanity_check Flag used to disable the sanity check
      *        on the size of the transmitList. The check is enabled by default.
      */
     PacketQueue(EventManager& _em, const std::string& _label,
                 const std::string& _sendEventName,
                 bool force_order = false,
                 bool disable_sanity_check = false);

     /**
      * Virtual desctructor since the class may be used as a base class.
      */
     virtual ~PacketQueue();

   public:

     /**
      * Provide a name to simplify debugging.
      *
      * @return A complete name, appended to module and port
      */
     virtual const std::string name() const = 0;

     /**
      * Get the size of the queue.
      */
     size_t size() const { return transmitList.size(); }

     /**
      * Get the next packet ready time.
      */
     Tick deferredPacketReadyTime() const
     { return transmitList.empty() ? MaxTick : transmitList.front().tick; }

     /**
      * Check if a packet corresponding to the same address exists in the
      * queue.
      *
      * @param pkt The packet to compare against.
      * @param blk_size Block size in bytes.
      * @return Whether a corresponding packet is found.
      */
     bool checkConflict(const PacketPtr pkt, const int blk_size) const;

     /** Check the list of buffered packets against the supplied
      * functional request. */
     bool trySatisfyFunctional(PacketPtr pkt);

     /**
      * Schedule a send event if we are not already waiting for a
      * retry. If the requested time is before an already scheduled
      * send event, the event will be rescheduled. If MaxTick is
      * passed, no event is scheduled. Instead, if we are idle and
      * asked to drain then check and signal drained.
      *
      * @param when time to schedule an event
      */
     void schedSendEvent(Tick when);

     /**
      * Add a packet to the transmit list, and schedule a send event.
      *
      * @param pkt Packet to send
      * @param when Absolute time (in ticks) to send packet
      */
     void schedSendTiming(PacketPtr pkt, Tick when);

     /**
      * Retry sending a packet from the queue. Note that this is not
      * necessarily the same packet if something has been added with an
      * earlier time stamp.
      */
     void retry();

     /**
       * This allows a user to explicitly disable the sanity check
       * on the size of the transmitList, which is enabled by default.
       * Users must use this function to explicitly disable the sanity
       * check.
       */
     void disableSanityCheck() { _disableSanityCheck = true; }

     DrainState drain() override;
 };

 class ReqPacketQueue : public PacketQueue
 {

   protected:

     RequestPort& memSidePort;

     // Static definition so it can be called when constructing the parent
     // without us being completely initialized.
     static const std::string name(const RequestPort& memSidePort,
                                   const std::string& label)
     { return memSidePort.name() + "-" + label; }

   public:

     /**
      * Create a request packet queue, linked to an event manager, a
      * memory-side port, and a label that will be used for functional print
      * request packets.
      *
      * @param _em Event manager used for scheduling this queue
      * @param _mem_side_port Mem_side port used to send the packets
      * @param _label Label to push on the label stack for print request packets
      */
     ReqPacketQueue(EventManager& _em, RequestPort& _mem_side_port,
                    const std::string _label = "ReqPacketQueue");

     virtual ~ReqPacketQueue() { }

     const std::string name() const
     { return name(memSidePort, label); }

     bool sendTiming(PacketPtr pkt);

 };

 class SnoopRespPacketQueue : public PacketQueue
 {

   protected:

     RequestPort& memSidePort;

     // Static definition so it can be called when constructing the parent
     // without us being completely initialized.
     static const std::string name(const RequestPort& memSidePort,
                                   const std::string& label)
     { return memSidePort.name() + "-" + label; }

   public:

     /**
      * Create a snoop response packet queue, linked to an event
      * manager, a memory-side port, and a label that will be used for
      * functional print request packets.
      *
      * @param _em Event manager used for scheduling this queue
      * @param _mem_side_port memory-side port used to send the packets
      * @param force_order Force insertion order for packets with same address
      * @param _label Label to push on the label stack for print request packets
      */
     SnoopRespPacketQueue(EventManager& _em, RequestPort& _mem_side_port,
                          bool force_order = false,
                          const std::string _label = "SnoopRespPacketQueue");

     virtual ~SnoopRespPacketQueue() { }

     const std::string name() const
     { return name(memSidePort, label); }

     bool sendTiming(PacketPtr pkt);

 };

 class RespPacketQueue : public PacketQueue
 {

   protected:

     ResponsePort& cpuSidePort;

     // Static definition so it can be called when constructing the parent
     // without us being completely initialized.
     static const std::string name(const ResponsePort& cpuSidePort,
                                   const std::string& label)
     { return cpuSidePort.name() + "-" + label; }

   public:

     /**
      * Create a response packet queue, linked to an event manager, a
      * CPU-side port, and a label that will be used for functional print
      * request packets.
      *
      * @param _em Event manager used for scheduling this queue
      * @param _cpu_side_port Cpu_side port used to send the packets
      * @param force_order Force insertion order for packets with same address
      * @param _label Label to push on the label stack for print request packets
      */
     RespPacketQueue(EventManager& _em, ResponsePort& _cpu_side_port,
                     bool force_order = false,
                     const std::string _label = "RespPacketQueue");

     virtual ~RespPacketQueue() { }

     const std::string name() const
     { return name(cpuSidePort, label); }

     bool sendTiming(PacketPtr pkt);

 };

 #endif // __MEM_PACKET_QUEUE_HH__
	/*
	* Copyright (c) 2012,2015,2018 ARM Limited
	* All rights reserved.
	*
	* The license below extends only to copyright in the software and shall
	* not be construed as granting a license to any other intellectual
	* property including but not limited to intellectual property relating
	* to a hardware implementation of the functionality of the software
	* licensed hereunder. You may use the software subject to the license
	* terms below provided that you ensure that this notice is replicated
	* unmodified and in its entirety in all distributions of the software,
	* modified or unmodified, in source code or in binary form.
	*
	* Copyright (c) 2006 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.
	*/

	#ifndef __MEM_PACKET_QUEUE_HH__
	#define __MEM_PACKET_QUEUE_HH__

	/**
	* @file
	* Declaration of a simple PacketQueue that is associated with
	* a port on which it attempts to send packets according to the time
	* stamp given to them at insertion. The packet queue is responsible
	* for the flow control of the port.
	*/

	#include <list>

	#include "mem/port.hh"
	#include "sim/drain.hh"
	#include "sim/eventq.hh"

	/**
	* A packet queue is a class that holds deferred packets and later
	* sends them using the associated CPU-side port or memory-side port.
	*/
	class PacketQueue : public Drainable
	{
	private:
	/** A deferred packet, buffered to transmit later. */
	class DeferredPacket {
	public:
	Tick tick; ///< The tick when the packet is ready to transmit
	PacketPtr pkt; ///< Pointer to the packet to transmit
	DeferredPacket(Tick t, PacketPtr p)
	: tick(t), pkt(p)
	{}
	};

	typedef std::list<DeferredPacket> DeferredPacketList;

	/** A list of outgoing packets. */
	DeferredPacketList transmitList;

	/** The manager which is used for the event queue */
	EventManager& em;

	/** Used to schedule sending of deferred packets. */
	void processSendEvent();

	/** Event used to call processSendEvent. */
	EventFunctionWrapper sendEvent;

	/*
	* Optionally disable the sanity check
	* on the size of the transmitList. The
	* sanity check will be enabled by default.
	*/
	bool _disableSanityCheck;

	/**
	* if true, inserted packets have to be unconditionally scheduled
	* after the last packet in the queue that references the same
	* address
	*/
	bool forceOrder;

	protected:

	/** Label to use for print request packets label stack. */
	const std::string label;

	/** Remember whether we're awaiting a retry. */
	bool waitingOnRetry;

	/** Check whether we have a packet ready to go on the transmit list. */
	bool deferredPacketReady() const
	{ return !transmitList.empty() && transmitList.front().tick <= curTick(); }

	/**
	* Attempt to send a packet. Note that a subclass of the
	* PacketQueue can override this method and thus change the
	* behaviour (as done by the cache for the request queue). The
	* default implementation sends the head of the transmit list. The
	* caller must guarantee that the list is non-empty and that the
	* head packet is scheduled for curTick() (or earlier).
	*/
	virtual void sendDeferredPacket();

	/**
	* Send a packet using the appropriate method for the specific
	* subclass (request, response or snoop response).
	*/
	virtual bool sendTiming(PacketPtr pkt) = 0;

	/**
	* Create a packet queue, linked to an event manager, and a label
	* that will be used for functional print request packets.
	*
	* @param _em Event manager used for scheduling this queue
	* @param _label Label to push on the label stack for print request packets
	* @param force_order Force insertion order for packets with same address
	* @param disable_sanity_check Flag used to disable the sanity check
	* on the size of the transmitList. The check is enabled by default.
	*/
	PacketQueue(EventManager& _em, const std::string& _label,
	const std::string& _sendEventName,
	bool force_order = false,
	bool disable_sanity_check = false);

	/**
	* Virtual desctructor since the class may be used as a base class.
	*/
	virtual ~PacketQueue();

	public:

	/**
	* Provide a name to simplify debugging.
	*
	* @return A complete name, appended to module and port
	*/
	virtual const std::string name() const = 0;

	/**
	* Get the size of the queue.
	*/
	size_t size() const { return transmitList.size(); }

	/**
	* Get the next packet ready time.
	*/
	Tick deferredPacketReadyTime() const
	{ return transmitList.empty() ? MaxTick : transmitList.front().tick; }

	/**
	* Check if a packet corresponding to the same address exists in the
	* queue.
	*
	* @param pkt The packet to compare against.
	* @param blk_size Block size in bytes.
	* @return Whether a corresponding packet is found.
	*/
	bool checkConflict(const PacketPtr pkt, const int blk_size) const;

	/** Check the list of buffered packets against the supplied
	* functional request. */
	bool trySatisfyFunctional(PacketPtr pkt);

	/**
	* Schedule a send event if we are not already waiting for a
	* retry. If the requested time is before an already scheduled
	* send event, the event will be rescheduled. If MaxTick is
	* passed, no event is scheduled. Instead, if we are idle and
	* asked to drain then check and signal drained.
	*
	* @param when time to schedule an event
	*/
	void schedSendEvent(Tick when);

	/**
	* Add a packet to the transmit list, and schedule a send event.
	*
	* @param pkt Packet to send
	* @param when Absolute time (in ticks) to send packet
	*/
	void schedSendTiming(PacketPtr pkt, Tick when);

	/**
	* Retry sending a packet from the queue. Note that this is not
	* necessarily the same packet if something has been added with an
	* earlier time stamp.
	*/
	void retry();

	/**
	* This allows a user to explicitly disable the sanity check
	* on the size of the transmitList, which is enabled by default.
	* Users must use this function to explicitly disable the sanity
	* check.
	*/
	void disableSanityCheck() { _disableSanityCheck = true; }

	DrainState drain() override;
	};

	class ReqPacketQueue : public PacketQueue
	{

	protected:

	RequestPort& memSidePort;

	// Static definition so it can be called when constructing the parent
	// without us being completely initialized.
	static const std::string name(const RequestPort& memSidePort,
	const std::string& label)
	{ return memSidePort.name() + "-" + label; }

	public:

	/**
	* Create a request packet queue, linked to an event manager, a
	* memory-side port, and a label that will be used for functional print
	* request packets.
	*
	* @param _em Event manager used for scheduling this queue
	* @param _mem_side_port Mem_side port used to send the packets
	* @param _label Label to push on the label stack for print request packets
	*/
	ReqPacketQueue(EventManager& _em, RequestPort& _mem_side_port,
	const std::string _label = "ReqPacketQueue");

	virtual ~ReqPacketQueue() { }

	const std::string name() const
	{ return name(memSidePort, label); }

	bool sendTiming(PacketPtr pkt);

	};

	class SnoopRespPacketQueue : public PacketQueue
	{

	protected:

	RequestPort& memSidePort;

	// Static definition so it can be called when constructing the parent
	// without us being completely initialized.
	static const std::string name(const RequestPort& memSidePort,
	const std::string& label)
	{ return memSidePort.name() + "-" + label; }

	public:

	/**
	* Create a snoop response packet queue, linked to an event
	* manager, a memory-side port, and a label that will be used for
	* functional print request packets.
	*
	* @param _em Event manager used for scheduling this queue
	* @param _mem_side_port memory-side port used to send the packets
	* @param force_order Force insertion order for packets with same address
	* @param _label Label to push on the label stack for print request packets
	*/
	SnoopRespPacketQueue(EventManager& _em, RequestPort& _mem_side_port,
	bool force_order = false,
	const std::string _label = "SnoopRespPacketQueue");

	virtual ~SnoopRespPacketQueue() { }

	const std::string name() const
	{ return name(memSidePort, label); }

	bool sendTiming(PacketPtr pkt);

	};

	class RespPacketQueue : public PacketQueue
	{

	protected:

	ResponsePort& cpuSidePort;

	// Static definition so it can be called when constructing the parent
	// without us being completely initialized.
	static const std::string name(const ResponsePort& cpuSidePort,
	const std::string& label)
	{ return cpuSidePort.name() + "-" + label; }

	public:

	/**
	* Create a response packet queue, linked to an event manager, a
	* CPU-side port, and a label that will be used for functional print
	* request packets.
	*
	* @param _em Event manager used for scheduling this queue
	* @param _cpu_side_port Cpu_side port used to send the packets
	* @param force_order Force insertion order for packets with same address
	* @param _label Label to push on the label stack for print request packets
	*/
	RespPacketQueue(EventManager& _em, ResponsePort& _cpu_side_port,
	bool force_order = false,
	const std::string _label = "RespPacketQueue");

	virtual ~RespPacketQueue() { }

	const std::string name() const
	{ return name(cpuSidePort, label); }

	bool sendTiming(PacketPtr pkt);

	};

	#endif // __MEM_PACKET_QUEUE_HH__