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
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   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,
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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         Tick tick;
  59         PacketPtr pkt;
  60         int32_t priority;
  61         DeferredPacket(Tick t, PacketPtr p, int32_t pr) : tick(t), pkt(p),
  62                                                         priority(pr)  {}
  63         bool operator>(const DeferredPacket& that) const
  64         {
  65             return priority > that.priority;
  66         }
  67         bool operator<(const DeferredPacket& that) const
  68         {
  69             return priority < that.priority;
  70         }
  71         bool operator<=(const DeferredPacket& that) const
  72         {
  73             return !(*this > that);
  74         }
  75     };
  76     using AddrPriority = std::pair<Addr, int32_t>;
  77
  78     std::list<DeferredPacket> pfq;
  79
  80     // PARAMETERS
  81
  82     /** Maximum size of the prefetch queue */
  83     const unsigned queueSize;
  84
  85     /** Cycles after generation when a prefetch can first be issued */
  86     const Cycles latency;
  87
  88     /** Squash queued prefetch if demand access observed */
  89     const bool queueSquash;
  90
  91     /** Filter prefetches if already queued */
  92     const bool queueFilter;
  93
  94     /** Snoop the cache before generating prefetch (cheating basically) */
  95     const bool cacheSnoop;
  96
  97     /** Tag prefetch with PC of generating access? */
  98     const bool tagPrefetch;
  99
 100     using const_iterator = std::list<DeferredPacket>::const_iterator;
 101     const_iterator inPrefetch(Addr address, bool is_secure) const;
 102     using iterator = std::list<DeferredPacket>::iterator;
 103     iterator inPrefetch(Addr address, bool is_secure);
 104
 105     // STATS
 106     Stats::Scalar pfIdentified;
 107     Stats::Scalar pfBufferHit;
 108     Stats::Scalar pfInCache;
 109     Stats::Scalar pfRemovedFull;
 110     Stats::Scalar pfSpanPage;
 111
 112   public:
 113     QueuedPrefetcher(const QueuedPrefetcherParams *p);
 114     virtual ~QueuedPrefetcher();
 115
 116     void notify(const PacketPtr &pkt) override;
 117
 118     PacketPtr insert(AddrPriority& info, bool is_secure);
 119
 120     virtual void calculatePrefetch(const PacketPtr &pkt,
 121                                    std::vector<AddrPriority> &addresses) = 0;
 122     PacketPtr getPacket() override;
 123
 124     Tick nextPrefetchReadyTime() const override
 125     {
 126         return pfq.empty() ? MaxTick : pfq.front().tick;
 127     }
 128
 129     void regStats() override;
 130 };
 131
 132 #endif //__MEM_CACHE_PREFETCH_QUEUED_HH__
 133