src/mem/cache/prefetch/signature_path_v2.hh

   1 /**
   2  * Copyright (c) 2018 Metempsy Technology Consulting
   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: Javier Bueno
  29  */
  30
  31  /**
  32   * Implementation of the Signature Path Prefetcher (v2)
  33   *
  34   * References:
  35   *     Path confidence based lookahead prefetching
  36   *     Jinchun Kim, Seth H. Pugsley, Paul V. Gratz, A. L. Narasimha Reddy,
  37   *     Chris Wilkerson, and Zeshan Chishti. 2016.
  38   *     In The 49th Annual IEEE/ACM International Symposium on
  39   *     Microarchitecture (MICRO-49). IEEE Press, Piscataway, NJ, USA,
  40   *     Article 60, 12 pages.
  41   */
  42
  43 #ifndef __MEM_CACHE_PREFETCH_SIGNATURE_PATH_V2_HH__
  44 #define __MEM_CACHE_PREFETCH_SIGNATURE_PATH_V2_HH__
  45
  46 #include "mem/cache/prefetch/associative_set.hh"
  47 #include "mem/cache/prefetch/signature_path.hh"
  48 #include "mem/packet.hh"
  49
  50 struct SignaturePathPrefetcherV2Params;
  51
  52 class SignaturePathPrefetcherV2 : public SignaturePathPrefetcher
  53 {
  54     /** Global History Register entry datatype */
  55     struct GlobalHistoryEntry : public TaggedEntry
  56     {
  57         signature_t signature;
  58         double confidence;
  59         stride_t lastBlock;
  60         stride_t delta;
  61         GlobalHistoryEntry() : signature(0), confidence(0.0), lastBlock(0),
  62                                delta(0) {}
  63     };
  64     /** Global History Register */
  65     AssociativeSet<GlobalHistoryEntry> globalHistoryRegister;
  66
  67     double calculateLookaheadConfidence(PatternEntry const &sig,
  68             PatternStrideEntry const &lookahead) const override;
  69
  70     double calculatePrefetchConfidence(PatternEntry const &sig,
  71             PatternStrideEntry const &lookahead) const override;
  72
  73     void increasePatternEntryCounter(PatternEntry &pattern_entry,
  74             PatternStrideEntry &pstride_entry) override;
  75
  76     void handleSignatureTableMiss(stride_t current_block,
  77             signature_t &new_signature, double &new_conf,
  78             stride_t &new_stride) override;
  79
  80     /**
  81      * In this version of the Signature Path Prefetcher, there is no auxiliary
  82      * prefetcher, so this function does not perform any actions.
  83      */
  84     void auxiliaryPrefetcher(Addr ppn, stride_t current_block, bool is_secure,
  85             std::vector<AddrPriority> &addresses) override
  86     {}
  87
  88     virtual void handlePageCrossingLookahead(signature_t signature,
  89             stride_t last_offset, stride_t delta, double path_confidence)
  90             override;
  91
  92   public:
  93     SignaturePathPrefetcherV2(const SignaturePathPrefetcherV2Params* p);
  94     ~SignaturePathPrefetcherV2() {}
  95 };
  96
  97 #endif//__MEM_CACHE_PREFETCH_SIGNATURE_PATH_V2_HH__