random_rp.cc 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#include "mem/cache/replacement_policies/random_rp.hh"
32
33#include "base/random.hh"
34#include "mem/cache/blk.hh"
35
36RandomRP::RandomRP(const Params *p)
37    : BaseReplacementPolicy(p)
38{
39}
40
41void
42RandomRP::invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
43const
44{
45    // Unprioritize replacement data victimization
46    std::static_pointer_cast<RandomReplData>(
47        replacement_data)->valid = false;
48}
49
50void
51RandomRP::touch(const std::shared_ptr<ReplacementData>& replacement_data) const
52{
53}
54
55void
56RandomRP::reset(const std::shared_ptr<ReplacementData>& replacement_data) const
57{
58    // Unprioritize replacement data victimization
59    std::static_pointer_cast<RandomReplData>(
60        replacement_data)->valid = true;
61}
62
63ReplaceableEntry*
64RandomRP::getVictim(const ReplacementCandidates& candidates) const
65{
66    // There must be at least one replacement candidate
67    assert(candidates.size() > 0);
68
69    // Choose one candidate at random
70    ReplaceableEntry* victim = candidates[random_mt.random<unsigned>(0,
71                                    candidates.size() - 1)];
72
73    // Visit all candidates to search for an invalid entry. If one is found,
74    // its eviction is prioritized
75    for (const auto& candidate : candidates) {
76        if (!std::static_pointer_cast<RandomReplData>(
77                    candidate->replacementData)->valid) {
78            victim = candidate;
79            break;
80        }
81    }
82
83    return victim;
84}
85
86std::shared_ptr<ReplacementData>
87RandomRP::instantiateEntry()
88{
89    return std::shared_ptr<ReplacementData>(new ReplacementData());
90}
91
92RandomRP*
93RandomRPParams::create()
94{
95    return new RandomRP(this);
96}
97