lfu_rp.hh revision 12684
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 Frequently Used replacement policy. 34 * The victim is chosen using the reference frequency. The least referenced 35 * entry is always chosen to be evicted, regardless of the amount of times 36 * it has been touched, or how long has passed since its last touch. 37 */ 38 39#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_LFU_RP_HH__ 40#define __MEM_CACHE_REPLACEMENT_POLICIES_LFU_RP_HH__ 41 42#include "mem/cache/replacement_policies/base.hh" 43#include "params/LFURP.hh" 44 45class LFURP : public BaseReplacementPolicy 46{ 47 protected: 48 /** LFU-specific implementation of replacement data. */ 49 struct LFUReplData : ReplacementData 50 { 51 /** Number of references to this entry since it was reset. */ 52 unsigned refCount; 53 54 /** 55 * Default constructor. Invalidate data. 56 */ 57 LFUReplData() : refCount(0) {} 58 }; 59 60 public: 61 /** Convenience typedef. */ 62 typedef LFURPParams Params; 63 64 /** 65 * Construct and initiliaze this replacement policy. 66 */ 67 LFURP(const Params *p); 68 69 /** 70 * Destructor. 71 */ 72 ~LFURP() {} 73 74 /** 75 * Invalidate replacement data to set it as the next probable victim. 76 * Clear the number of references. 77 * 78 * @param replacement_data Replacement data to be invalidated. 79 */ 80 void invalidate(const std::shared_ptr<ReplacementData>& replacement_data) 81 const override; 82 83 /** 84 * Touch an entry to update its replacement data. 85 * Increase number of references. 86 * 87 * @param replacement_data Replacement data to be touched. 88 */ 89 void touch(const std::shared_ptr<ReplacementData>& replacement_data) const 90 override; 91 92 /** 93 * Reset replacement data. Used when an entry is inserted. 94 * Reset number of references. 95 * 96 * @param replacement_data Replacement data to be reset. 97 */ 98 void reset(const std::shared_ptr<ReplacementData>& replacement_data) const 99 override; 100 101 /** 102 * Find replacement victim using reference frequency. 103 * 104 * @param cands Replacement candidates, selected by indexing policy. 105 * @return Replacement entry to be replaced. 106 */ 107 ReplaceableEntry* getVictim(const ReplacementCandidates& candidates) const 108 override; 109 110 /** 111 * Instantiate a replacement data entry. 112 * 113 * @return A shared pointer to the new replacement data. 114 */ 115 std::shared_ptr<ReplacementData> instantiateEntry() override; 116}; 117 118#endif // __MEM_CACHE_REPLACEMENT_POLICIES_LFU_RP_HH__ 119