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28 * Authors: Daniel Carvalho
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.
39 #ifndef __MEM_CACHE_REPLACEMENT_POLICIES_LFU_RP_HH__
40 #define __MEM_CACHE_REPLACEMENT_POLICIES_LFU_RP_HH__
42 #include "mem/cache/replacement_policies/base.hh"
46 class LFURP : public BaseReplacementPolicy
49 /** LFU-specific implementation of replacement data. */
50 struct LFUReplData : ReplacementData
52 /** Number of references to this entry since it was reset. */
56 * Default constructor. Invalidate data.
58 LFUReplData() : refCount(0) {}
62 /** Convenience typedef. */
63 typedef LFURPParams Params;
66 * Construct and initiliaze this replacement policy.
68 LFURP(const Params *p);
76 * Invalidate replacement data to set it as the next probable victim.
77 * Clear the number of references.
79 * @param replacement_data Replacement data to be invalidated.
81 void invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
85 * Touch an entry to update its replacement data.
86 * Increase number of references.
88 * @param replacement_data Replacement data to be touched.
90 void touch(const std::shared_ptr<ReplacementData>& replacement_data) const
94 * Reset replacement data. Used when an entry is inserted.
95 * Reset number of references.
97 * @param replacement_data Replacement data to be reset.
99 void reset(const std::shared_ptr<ReplacementData>& replacement_data) const
103 * Find replacement victim using reference frequency.
105 * @param cands Replacement candidates, selected by indexing policy.
106 * @return Replacement entry to be replaced.
108 ReplaceableEntry* getVictim(const ReplacementCandidates& candidates) const
112 * Instantiate a replacement data entry.
114 * @return A shared pointer to the new replacement data.
116 std::shared_ptr<ReplacementData> instantiateEntry() override;
119 #endif // __MEM_CACHE_REPLACEMENT_POLICIES_LFU_RP_HH__