src/mem/cache/replacement_policies/lfu_rp.cc

   1 /**
   2  * Copyright (c) 2018 Inria
   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: Daniel Carvalho
  29  */
  30
  31 #include "mem/cache/replacement_policies/lfu_rp.hh"
  32
  33 #include <cassert>
  34 #include <memory>
  35
  36 #include "params/LFURP.hh"
  37
  38 LFURP::LFURP(const Params *p)
  39     : BaseReplacementPolicy(p)
  40 {
  41 }
  42
  43 void
  44 LFURP::invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
  45 const
  46 {
  47     // Reset reference count
  48     std::static_pointer_cast<LFUReplData>(replacement_data)->refCount = 0;
  49 }
  50
  51 void
  52 LFURP::touch(const std::shared_ptr<ReplacementData>& replacement_data) const
  53 {
  54     // Update reference count
  55     std::static_pointer_cast<LFUReplData>(replacement_data)->refCount++;
  56 }
  57
  58 void
  59 LFURP::reset(const std::shared_ptr<ReplacementData>& replacement_data) const
  60 {
  61     // Reset reference count
  62     std::static_pointer_cast<LFUReplData>(replacement_data)->refCount = 1;
  63 }
  64
  65 ReplaceableEntry*
  66 LFURP::getVictim(const ReplacementCandidates& candidates) const
  67 {
  68     // There must be at least one replacement candidate
  69     assert(candidates.size() > 0);
  70
  71     // Visit all candidates to find victim
  72     ReplaceableEntry* victim = candidates[0];
  73     for (const auto& candidate : candidates) {
  74         // Update victim entry if necessary
  75         if (std::static_pointer_cast<LFUReplData>(
  76                     candidate->replacementData)->refCount <
  77                 std::static_pointer_cast<LFUReplData>(
  78                     victim->replacementData)->refCount) {
  79             victim = candidate;
  80         }
  81     }
  82
  83     return victim;
  84 }
  85
  86 std::shared_ptr<ReplacementData>
  87 LFURP::instantiateEntry()
  88 {
  89     return std::shared_ptr<ReplacementData>(new LFUReplData());
  90 }
  91
  92 LFURP*
  93 LFURPParams::create()
  94 {
  95     return new LFURP(this);
  96 }