src/mem/cache/prefetch/queued.hh

   1 /*
   2  * Copyright (c) 2014-2015 ARM Limited
   3  * All rights reserved
   4  *
   5  * The license below extends only to copyright in the software and shall
   6  * not be construed as granting a license to any other intellectual
   7  * property including but not limited to intellectual property relating
   8  * to a hardware implementation of the functionality of the software
   9  * licensed hereunder.  You may use the software subject to the license
  10  * terms below provided that you ensure that this notice is replicated
  11  * unmodified and in its entirety in all distributions of the software,
  12  * modified or unmodified, in source code or in binary form.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions are
  16  * met: redistributions of source code must retain the above copyright
  17  * notice, this list of conditions and the following disclaimer;
  18  * redistributions in binary form must reproduce the above copyright
  19  * notice, this list of conditions and the following disclaimer in the
  20  * documentation and/or other materials provided with the distribution;
  21  * neither the name of the copyright holders nor the names of its
  22  * contributors may be used to endorse or promote products derived from
  23  * this software without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  26  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  27  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  28  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  29  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  31  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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  35  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  *
  37  * Authors: Mitch Hayenga
  38  */
  39
  40 #ifndef __MEM_CACHE_PREFETCH_QUEUED_HH__
  41 #define __MEM_CACHE_PREFETCH_QUEUED_HH__
  42
  43 #include <cstdint>
  44 #include <list>
  45 #include <utility>
  46
  47 #include "base/statistics.hh"
  48 #include "base/types.hh"
  49 #include "mem/cache/prefetch/base.hh"
  50 #include "mem/packet.hh"
  51
  52 struct QueuedPrefetcherParams;
  53
  54 class QueuedPrefetcher : public BasePrefetcher
  55 {
  56   protected:
  57     struct DeferredPacket {
  58         /** Prefetch info corresponding to this packet */
  59         PrefetchInfo pfInfo;
  60         /** Time when this prefetch becomes ready */
  61         Tick tick;
  62         /** The memory packet generated by this prefetch */
  63         PacketPtr pkt;
  64         /** The priority of this prefetch */
  65         int32_t priority;
  66
  67         /**
  68          * Constructor
  69          * @param pfi PrefechInfo object associated to this packet
  70          * @param t Time when this prefetch becomes ready
  71          * @param p PacketPtr with the memory request of the prefetch
  72          * @param prio This prefetch priority
  73          */
  74         DeferredPacket(PrefetchInfo const &pfi, Tick t, PacketPtr p,
  75                        int32_t prio) : pfInfo(pfi), tick(t), pkt(p),
  76                        priority(prio) {
  77         }
  78
  79         bool operator>(const DeferredPacket& that) const
  80         {
  81             return priority > that.priority;
  82         }
  83         bool operator<(const DeferredPacket& that) const
  84         {
  85             return priority < that.priority;
  86         }
  87         bool operator<=(const DeferredPacket& that) const
  88         {
  89             return !(*this > that);
  90         }
  91     };
  92     using AddrPriority = std::pair<Addr, int32_t>;
  93
  94     std::list<DeferredPacket> pfq;
  95
  96     // PARAMETERS
  97
  98     /** Maximum size of the prefetch queue */
  99     const unsigned queueSize;
 100
 101     /** Cycles after generation when a prefetch can first be issued */
 102     const Cycles latency;
 103
 104     /** Squash queued prefetch if demand access observed */
 105     const bool queueSquash;
 106
 107     /** Filter prefetches if already queued */
 108     const bool queueFilter;
 109
 110     /** Snoop the cache before generating prefetch (cheating basically) */
 111     const bool cacheSnoop;
 112
 113     /** Tag prefetch with PC of generating access? */
 114     const bool tagPrefetch;
 115
 116     using const_iterator = std::list<DeferredPacket>::const_iterator;
 117     const_iterator inPrefetch(const PrefetchInfo &pfi) const;
 118     using iterator = std::list<DeferredPacket>::iterator;
 119     iterator inPrefetch(const PrefetchInfo &pfi);
 120
 121     // STATS
 122     Stats::Scalar pfIdentified;
 123     Stats::Scalar pfBufferHit;
 124     Stats::Scalar pfInCache;
 125     Stats::Scalar pfRemovedFull;
 126     Stats::Scalar pfSpanPage;
 127
 128   public:
 129     QueuedPrefetcher(const QueuedPrefetcherParams *p);
 130     virtual ~QueuedPrefetcher();
 131
 132     void notify(const PacketPtr &pkt, const PrefetchInfo &pfi) override;
 133
 134     void insert(const PacketPtr &pkt, PrefetchInfo &new_pfi, int32_t priority);
 135
 136     virtual void calculatePrefetch(const PrefetchInfo &pfi,
 137                                    std::vector<AddrPriority> &addresses) = 0;
 138     PacketPtr getPacket() override;
 139
 140     Tick nextPrefetchReadyTime() const override
 141     {
 142         return pfq.empty() ? MaxTick : pfq.front().tick;
 143     }
 144
 145     void regStats() override;
 146 };
 147
 148 #endif //__MEM_CACHE_PREFETCH_QUEUED_HH__
 149