packet.hh

来自「M5,一个功能强大的多处理器系统模拟器.很多针对处理器架构,性能的研究都使用它作」· HH 代码 · 共 666 行 · 第 1/2 页

/*
 * Copyright (c) 2006
 * The Regents of The University of Michigan
 * All Rights Reserved
 *
 * This code is part of the M5 simulator.
 *
 * Permission is granted to use, copy, create derivative works and
 * redistribute this software and such derivative works for any
 * purpose, so long as the copyright notice above, this grant of
 * permission, and the disclaimer below appear in all copies made; and
 * so long as the name of The University of Michigan is not used in
 * any advertising or publicity pertaining to the use or distribution
 * of this software without specific, written prior authorization.
 *
 * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION FROM THE
 * UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY PURPOSE, AND
 * WITHOUT WARRANTY BY THE UNIVERSITY OF MICHIGAN OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE. THE REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE
 * LIABLE FOR ANY DAMAGES, INCLUDING DIRECT, SPECIAL, INDIRECT,
 * INCIDENTAL, OR CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM
 * ARISING OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
 * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGES.
 *
 * Authors: Ronald G. Dreslinski Jr
 *          Steven K. Reinhardt
 *          Ali G. Saidi
 */

/**
 * @file
 * Declaration of the Packet class.
 */

#ifndef __MEM_PACKET_HH__
#define __MEM_PACKET_HH__

#include <cassert>
#include <list>
#include <bitset>

#include "base/compiler.hh"
#include "base/fast_alloc.hh"
#include "base/misc.hh"
#include "base/printable.hh"
#include "mem/request.hh"
#include "sim/host.hh"
#include "sim/core.hh"


struct Packet;
typedef Packet *PacketPtr;
typedef uint8_t* PacketDataPtr;
typedef std::list<PacketPtr> PacketList;

class MemCmd
{
  public:

    /** List of all commands associated with a packet. */
    enum Command
    {
        InvalidCmd,
        ReadReq,
        ReadResp,
        ReadRespWithInvalidate,
        WriteReq,
        WriteResp,
        Writeback,
        SoftPFReq,
        HardPFReq,
        SoftPFResp,
        HardPFResp,
        WriteInvalidateReq,
        WriteInvalidateResp,
        UpgradeReq,
        UpgradeResp,
        ReadExReq,
        ReadExResp,
        LoadLockedReq,
        LoadLockedResp,
        StoreCondReq,
        StoreCondResp,
        SwapReq,
        SwapResp,
        // Error responses
        // @TODO these should be classified as responses rather than
        // requests; coding them as requests initially for backwards
        // compatibility
        NetworkNackError,  // nacked at network layer (not by protocol)
        InvalidDestError,  // packet dest field invalid
        BadAddressError,   // memory address invalid
        // Fake simulator-only commands
        PrintReq,       // Print state matching address
        NUM_MEM_CMDS
    };

  private:
    /** List of command attributes. */
    enum Attribute
    {
        IsRead,         //!< Data flows from responder to requester
        IsWrite,        //!< Data flows from requester to responder
        IsPrefetch,     //!< Not a demand access
        IsInvalidate,
        NeedsExclusive, //!< Requires exclusive copy to complete in-cache
        IsRequest,      //!< Issued by requester
        IsResponse,     //!< Issue by responder
        NeedsResponse,  //!< Requester needs response from target
        IsSWPrefetch,
        IsHWPrefetch,
        IsLocked,       //!< Alpha/MIPS LL or SC access
        HasData,        //!< There is an associated payload
        IsError,        //!< Error response
        IsPrint,        //!< Print state matching address (for debugging)
        NUM_COMMAND_ATTRIBUTES
    };

    /** Structure that defines attributes and other data associated
     * with a Command. */
    struct CommandInfo {
        /** Set of attribute flags. */
        const std::bitset<NUM_COMMAND_ATTRIBUTES> attributes;
        /** Corresponding response for requests; InvalidCmd if no
         * response is applicable. */
        const Command response;
        /** String representation (for printing) */
        const std::string str;
    };

    /** Array to map Command enum to associated info. */
    static const CommandInfo commandInfo[];

  private:

    Command cmd;

    bool testCmdAttrib(MemCmd::Attribute attrib) const {
        return commandInfo[cmd].attributes[attrib] != 0;
    }

  public:

    bool isRead() const         { return testCmdAttrib(IsRead); }
    bool isWrite()  const       { return testCmdAttrib(IsWrite); }
    bool isRequest() const      { return testCmdAttrib(IsRequest); }
    bool isResponse() const     { return testCmdAttrib(IsResponse); }
    bool needsExclusive() const { return testCmdAttrib(NeedsExclusive); }
    bool needsResponse() const  { return testCmdAttrib(NeedsResponse); }
    bool isInvalidate() const   { return testCmdAttrib(IsInvalidate); }
    bool hasData() const        { return testCmdAttrib(HasData); }
    bool isReadWrite() const    { return isRead() && isWrite(); }
    bool isLocked() const       { return testCmdAttrib(IsLocked); }
    bool isError() const        { return testCmdAttrib(IsError); }
    bool isPrint() const        { return testCmdAttrib(IsPrint); }

    const Command responseCommand() const {
        return commandInfo[cmd].response;
    }

    /** Return the string to a cmd given by idx. */
    const std::string &toString() const {
        return commandInfo[cmd].str;
    }

    int toInt() const { return (int)cmd; }

    MemCmd(Command _cmd)
        : cmd(_cmd)
    { }

    MemCmd(int _cmd)
        : cmd((Command)_cmd)
    { }

    MemCmd()
        : cmd(InvalidCmd)
    { }

    bool operator==(MemCmd c2) { return (cmd == c2.cmd); }
    bool operator!=(MemCmd c2) { return (cmd != c2.cmd); }

    friend class Packet;
};

/**
 * A Packet is used to encapsulate a transfer between two objects in
 * the memory system (e.g., the L1 and L2 cache).  (In contrast, a
 * single Request travels all the way from the requester to the
 * ultimate destination and back, possibly being conveyed by several
 * different Packets along the way.)
 */
class Packet : public FastAlloc, public Printable
{
  public:

    typedef MemCmd::Command Command;

    /** The command field of the packet. */
    MemCmd cmd;

    /** A pointer to the original request. */
    RequestPtr req;

  private:
   /** A pointer to the data being transfered.  It can be differnt
    *    sizes at each level of the heirarchy so it belongs in the
    *    packet, not request. This may or may not be populated when a
    *    responder recieves the packet. If not populated it memory
    *    should be allocated.
    */
    PacketDataPtr data;

    /** Is the data pointer set to a value that shouldn't be freed
     *   when the packet is destroyed? */
    bool staticData;
    /** The data pointer points to a value that should be freed when
     *   the packet is destroyed. */
    bool dynamicData;
    /** the data pointer points to an array (thus delete [] ) needs to
     *   be called on it rather than simply delete.*/
    bool arrayData;

    /** The address of the request.  This address could be virtual or
     *   physical, depending on the system configuration. */
    Addr addr;

     /** The size of the request or transfer. */
    int size;

    /** Device address (e.g., bus ID) of the source of the
     *   transaction. The source is not responsible for setting this
     *   field; it is set implicitly by the interconnect when the
     *   packet is first sent.  */
    short src;

    /** Device address (e.g., bus ID) of the destination of the
     *   transaction. The special value Broadcast indicates that the
     *   packet should be routed based on its address. This field is
     *   initialized in the constructor and is thus always valid
     *   (unlike * addr, size, and src). */
    short dest;

    /** The original value of the command field.  Only valid when the
     * current command field is an error condition; in that case, the
     * previous contents of the command field are copied here.  This
     * field is *not* set on non-error responses.
     */
    MemCmd origCmd;

    /** Are the 'addr' and 'size' fields valid? */
    bool addrSizeValid;
    /** Is the 'src' field valid? */
    bool srcValid;
    bool destValid;

    enum Flag {
        // Snoop response flags
        MemInhibit,
        Shared,
        // Special control flags
        /// Special timing-mode atomic snoop for multi-level coherence.
        ExpressSnoop,
        /// Does supplier have exclusive copy?
        /// Useful for multi-level coherence.
        SupplyExclusive,
        NUM_PACKET_FLAGS
    };

    /** Status flags */
    std::bitset<NUM_PACKET_FLAGS> flags;

  public:

    /** Used to calculate latencies for each packet.*/
    Tick time;

    /** The time at which the packet will be fully transmitted */
    Tick finishTime;

    /** The time at which the first chunk of the packet will be transmitted */
    Tick firstWordTime;

    /** The special destination address indicating that the packet
     *   should be routed based on its address. */
    static const short Broadcast = -1;

    /** A virtual base opaque structure used to hold state associated
     *    with the packet but specific to the sending device (e.g., an
     *    MSHR).  A pointer to this state is returned in the packet's
     *    response so that the sender can quickly look up the state
     *    needed to process it.  A specific subclass would be derived
     *    from this to carry state specific to a particular sending
     *    device.  */
    class SenderState : public FastAlloc {
      public:
        virtual ~SenderState() {}
    };

    /**
     * Object used to maintain state of a PrintReq.  The senderState
     * field of a PrintReq should always be of this type.
     */
    class PrintReqState : public SenderState {
        /** An entry in the label stack. */
        class LabelStackEntry {
          public:
            const std::string label;
            std::string *prefix;
            bool labelPrinted;
            LabelStackEntry(const std::string &_label,
                            std::string *_prefix);
        };

        typedef std::list<LabelStackEntry> LabelStack;
        LabelStack labelStack;

        std::string *curPrefixPtr;

      public:
        std::ostream &os;
        const int verbosity;

        PrintReqState(std::ostream &os, int verbosity = 0);
        ~PrintReqState();

        /** Returns the current line prefix. */
        const std::string &curPrefix() { return *curPrefixPtr; }

        /** Push a label onto the label stack, and prepend the given