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
42struct RandomRPParams;
43
44class RandomRP : public BaseReplacementPolicy
45{
46 protected:
47 /** MRU-specific implementation of replacement data. */
48 struct RandomReplData : ReplacementData
49 {
50 /**
51 * Flag informing if the replacement data is valid or not.
52 * Invalid entries are prioritized to be evicted.
53 */
54 bool valid;
55
56 /**
57 * Default constructor. Invalidate data.
58 */
59 RandomReplData() : valid(false) {}
60 };
61
62 public:
63 /** Convenience typedef. */
64 typedef RandomRPParams Params;
65
66 /**
67 * Construct and initiliaze this replacement policy.
68 */
69 RandomRP(const Params *p);
70
71 /**
72 * Destructor.
73 */
74 ~RandomRP() {}
75
76 /**
77 * Invalidate replacement data to set it as the next probable victim.
78 * Prioritize replacement data for victimization.
79 *
80 * @param replacement_data Replacement data to be invalidated.
81 */
82 void invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
83 const override;
84
85 /**
86 * Touch an entry to update its replacement data.
87 * Does not do anything.
88 *
89 * @param replacement_data Replacement data to be touched.
90 */
91 void touch(const std::shared_ptr<ReplacementData>& replacement_data) const
92 override;
93
94 /**
95 * Reset replacement data. Used when an entry is inserted.
96 * Unprioritize replacement data for victimization.
97 *
98 * @param replacement_data Replacement data to be reset.
99 */
100 void reset(const std::shared_ptr<ReplacementData>& replacement_data) const
101 override;
102
103 /**
104 * Find replacement victim at random.
105 *
106 * @param candidates Replacement candidates, selected by indexing policy.
107 * @return Replacement entry to be replaced.
108 */
109 ReplaceableEntry* getVictim(const ReplacementCandidates& candidates) const
110 override;
111
112 /**
113 * Instantiate a replacement data entry.
114 *
115 * @return A shared pointer to the new replacement data.
116 */
117 std::shared_ptr<ReplacementData> instantiateEntry() override;
118};
119
120#endif // __MEM_CACHE_REPLACEMENT_POLICIES_RANDOM_RP_HH__