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 random replacement policy.
34 * The victim is chosen at random, if there are no invalid entries.
35 */
36
37#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_RANDOM_RP_HH__
38#define __MEM_CACHE_REPLACEMENT_POLICIES_RANDOM_RP_HH__
39
40#include "mem/cache/replacement_policies/base.hh"
41#include "params/RandomRP.hh"
42
43class RandomRP : public BaseReplacementPolicy
44{
45 protected:
46 /** MRU-specific implementation of replacement data. */
47 struct RandomReplData : ReplacementData
48 {
49 /**
50 * Flag informing if the replacement data is valid or not.
51 * Invalid entries are prioritized to be evicted.
52 */
53 bool valid;
54
55 /**
56 * Default constructor. Invalidate data.
57 */
58 RandomReplData() : valid(false) {}
59 };
60
61 public:
62 /** Convenience typedef. */
63 typedef RandomRPParams Params;
64
65 /**
66 * Construct and initiliaze this replacement policy.
67 */
68 RandomRP(const Params *p);
69
70 /**
71 * Destructor.
72 */
73 ~RandomRP() {}
74
75 /**
76 * Invalidate replacement data to set it as the next probable victim.
77 * Prioritize replacement data for victimization.
78 *
79 * @param replacement_data Replacement data to be invalidated.
80 */
81 void invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
82 const override;
83
84 /**
85 * Touch an entry to update its replacement data.
86 * Does not do anything.
87 *
88 * @param replacement_data Replacement data to be touched.
89 */
90 void touch(const std::shared_ptr<ReplacementData>& replacement_data) const
91 override;
92
93 /**
94 * Reset replacement data. Used when an entry is inserted.
95 * Unprioritize replacement data for victimization.
96 *
97 * @param replacement_data Replacement data to be reset.
98 */
99 void reset(const std::shared_ptr<ReplacementData>& replacement_data) const
100 override;
101
102 /**
103 * Find replacement victim at random.
104 *
105 * @param candidates Replacement candidates, selected by indexing policy.
106 * @return Replacement entry to be replaced.
107 */
108 ReplaceableEntry* getVictim(const ReplacementCandidates& candidates) const
109 override;
110
111 /**
112 * Instantiate a replacement data entry.
113 *
114 * @return A shared pointer to the new replacement data.
115 */
116 std::shared_ptr<ReplacementData> instantiateEntry() override;
117};
118
119#endif // __MEM_CACHE_REPLACEMENT_POLICIES_RANDOM_RP_HH__