src/mem/cache/miss/mshr.hh

   1 /*
   2  * Copyright (c) 2002-2005 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  * Authors: Erik Hallnor
  29  */
  30
  31 /**
  32  * @file
  33  * Miss Status and Handling Register (MSHR) declaration.
  34  */
  35
  36 #ifndef __MSHR_HH__
  37 #define __MSHR_HH__
  38
  39 #include "mem/packet.hh"
  40 #include <list>
  41 #include <deque>
  42
  43 class MSHR;
  44
  45 /**
  46  * Miss Status and handling Register. This class keeps all the information
  47  * needed to handle a cache miss including a list of target requests.
  48  */
  49 class MSHR {
  50   public:
  51     /** Defines the Data structure of the MSHR targetlist. */
  52     typedef std::list<Packet *> TargetList;
  53     /** Target list iterator. */
  54     typedef std::list<Packet *>::iterator TargetListIterator;
  55     /** A list of MSHRs. */
  56     typedef std::list<MSHR *> List;
  57     /** MSHR list iterator. */
  58     typedef List::iterator Iterator;
  59     /** MSHR list const_iterator. */
  60     typedef List::const_iterator ConstIterator;
  61
  62     /** Address of the miss. */
  63     Addr addr;
  64     /** Adress space id of the miss. */
  65     short asid;
  66     /** True if the request has been sent to the bus. */
  67     bool inService;
  68     /** Thread number of the miss. */
  69     int threadNum;
  70     /** The request that is forwarded to the next level of the hierarchy. */
  71     Packet * pkt;
  72     /** The number of currently allocated targets. */
  73     short ntargets;
  74     /** The original requesting command. */
  75     Packet::Command originalCmd;
  76     /** Order number of assigned by the miss queue. */
  77     uint64_t order;
  78
  79     /**
  80      * Pointer to this MSHR on the ready list.
  81      * @sa MissQueue, MSHRQueue::readyList
  82      */
  83     Iterator readyIter;
  84     /**
  85      * Pointer to this MSHR on the allocated list.
  86      * @sa MissQueue, MSHRQueue::allocatedList
  87      */
  88     Iterator allocIter;
  89
  90 private:
  91     /** List of all requests that match the address */
  92     TargetList targets;
  93
  94 public:
  95     /**
  96      * Allocate a miss to this MSHR.
  97      * @param cmd The requesting command.
  98      * @param addr The address of the miss.
  99      * @param asid The address space id of the miss.
 100      * @param size The number of bytes to request.
 101      * @param req  The original miss.
 102      */
 103     void allocate(Packet::Command cmd, Addr addr, int asid, int size,
 104                   Packet * &pkt);
 105
 106     /**
 107      * Allocate this MSHR as a buffer for the given request.
 108      * @param target The memory request to buffer.
 109      */
 110     void allocateAsBuffer(Packet * &target);
 111
 112     /**
 113      * Mark this MSHR as free.
 114      */
 115     void deallocate();
 116
 117     /**
 118      * Add a request to the list of targets.
 119      * @param target The target.
 120      */
 121     void allocateTarget(Packet * &target);
 122
 123     /** A simple constructor. */
 124     MSHR();
 125     /** A simple destructor. */
 126     ~MSHR();
 127
 128     /**
 129      * Returns the current number of allocated targets.
 130      * @return The current number of allocated targets.
 131      */
 132     int getNumTargets()
 133     {
 134         return(ntargets);
 135     }
 136
 137     /**
 138      * Returns a pointer to the target list.
 139      * @return a pointer to the target list.
 140      */
 141     TargetList* getTargetList()
 142     {
 143         return &targets;
 144     }
 145
 146     /**
 147      * Returns a reference to the first target.
 148      * @return A pointer to the first target.
 149      */
 150     Packet * getTarget()
 151     {
 152         return targets.front();
 153     }
 154
 155     /**
 156      * Pop first target.
 157      */
 158     void popTarget()
 159     {
 160         --ntargets;
 161         targets.pop_front();
 162     }
 163
 164     /**
 165      * Returns true if there are targets left.
 166      * @return true if there are targets
 167      */
 168     bool hasTargets()
 169     {
 170         return !targets.empty();
 171     }
 172
 173     /**
 174      * Prints the contents of this MSHR to stderr.
 175      */
 176     void dump();
 177 };
 178
 179 #endif //__MSHR_HH__