fifo_rp.hh revision 12684:44ebd2bc020f 
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 First In First Out replacement policy.
34 * The victim is chosen using the timestamp. The oldest entry is always chosen
35 * to be evicted, regardless of the amount of times it has been touched.
36 */
37
38#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_FIFO_RP_HH__
39#define __MEM_CACHE_REPLACEMENT_POLICIES_FIFO_RP_HH__
40
41#include "mem/cache/replacement_policies/base.hh"
42#include "params/FIFORP.hh"
43
44class FIFORP : public BaseReplacementPolicy
45{
46    /** FIFO-specific implementation of replacement data. */
47    struct FIFOReplData : ReplacementData
48    {
49        /** Tick on which the entry was inserted. */
50        Tick tickInserted;
51
52        /**
53         * Default constructor. Invalidate data.
54         */
55        FIFOReplData() : tickInserted(0) {}
56    };
57
58  public:
59    /** Convenience typedef. */
60    typedef FIFORPParams Params;
61
62    /**
63     * Construct and initiliaze this replacement policy.
64     */
65    FIFORP(const Params *p);
66
67    /**
68     * Destructor.
69     */
70    ~FIFORP() {}
71
72    /**
73     * Invalidate replacement data to set it as the next probable victim.
74     * Reset insertion tick to 0.
75     *
76     * @param replacement_data Replacement data to be invalidated.
77     */
78    void invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
79                                                              const override;
80
81    /**
82     * Touch an entry to update its replacement data.
83     * Does not modify the replacement data.
84     *
85     * @param replacement_data Replacement data to be touched.
86     */
87    void touch(const std::shared_ptr<ReplacementData>& replacement_data) const
88                                                                     override;
89
90    /**
91     * Reset replacement data. Used when an entry is inserted.
92     * Sets its insertion tick.
93     *
94     * @param replacement_data Replacement data to be reset.
95     */
96    void reset(const std::shared_ptr<ReplacementData>& replacement_data) const
97                                                                     override;
98
99    /**
100     * Find replacement victim using insertion timestamps.
101     *
102     * @param cands Replacement candidates, selected by indexing policy.
103     * @return Replacement entry to be replaced.
104     */
105    ReplaceableEntry* getVictim(const ReplacementCandidates& candidates) const
106                                                                     override;
107
108    /**
109     * Instantiate a replacement data entry.
110     *
111     * @return A shared pointer to the new replacement data.
112     */
113    std::shared_ptr<ReplacementData> instantiateEntry() override;
114};
115
116#endif // __MEM_CACHE_REPLACEMENT_POLICIES_FIFO_RP_HH__
117