lru_rp.hh revision 13221:48bce2835200
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/** 32 * @file 33 * Declaration of a Least Recently Used replacement policy. 34 * The victim is chosen using the last touch timestamp. 35 */ 36 37#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_LRU_RP_HH__ 38#define __MEM_CACHE_REPLACEMENT_POLICIES_LRU_RP_HH__ 39 40#include "mem/cache/replacement_policies/base.hh" 41 42struct LRURPParams; 43 44class LRURP : public BaseReplacementPolicy 45{ 46 protected: 47 /** LRU-specific implementation of replacement data. */ 48 struct LRUReplData : ReplacementData 49 { 50 /** Tick on which the entry was last touched. */ 51 Tick lastTouchTick; 52 53 /** 54 * Default constructor. Invalidate data. 55 */ 56 LRUReplData() : lastTouchTick(0) {} 57 }; 58 59 public: 60 /** Convenience typedef. */ 61 typedef LRURPParams Params; 62 63 /** 64 * Construct and initiliaze this replacement policy. 65 */ 66 LRURP(const Params *p); 67 68 /** 69 * Destructor. 70 */ 71 ~LRURP() {} 72 73 /** 74 * Invalidate replacement data to set it as the next probable victim. 75 * Sets its last touch tick as the starting tick. 76 * 77 * @param replacement_data Replacement data to be invalidated. 78 */ 79 void invalidate(const std::shared_ptr<ReplacementData>& replacement_data) 80 const override; 81 82 /** 83 * Touch an entry to update its replacement data. 84 * Sets its last touch tick as the current tick. 85 * 86 * @param replacement_data Replacement data to be touched. 87 */ 88 void touch(const std::shared_ptr<ReplacementData>& replacement_data) const 89 override; 90 91 /** 92 * Reset replacement data. Used when an entry is inserted. 93 * Sets its last touch tick as the current tick. 94 * 95 * @param replacement_data Replacement data to be reset. 96 */ 97 void reset(const std::shared_ptr<ReplacementData>& replacement_data) const 98 override; 99 100 /** 101 * Find replacement victim using LRU timestamps. 102 * 103 * @param candidates Replacement candidates, selected by indexing policy. 104 * @return Replacement entry to be replaced. 105 */ 106 ReplaceableEntry* getVictim(const ReplacementCandidates& candidates) const 107 override; 108 109 /** 110 * Instantiate a replacement data entry. 111 * 112 * @return A shared pointer to the new replacement data. 113 */ 114 std::shared_ptr<ReplacementData> instantiateEntry() override; 115}; 116 117#endif // __MEM_CACHE_REPLACEMENT_POLICIES_LRU_RP_HH__ 118