lru_rp.cc revision 12600:e670dd17c8cf 
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/lru_rp.hh"
32
33#include "debug/CacheRepl.hh"
34
35LRURP::LRURP(const Params *p)
36    : BaseReplacementPolicy(p)
37{
38}
39
40void
41LRURP::touch(CacheBlk *blk)
42{
43    BaseReplacementPolicy::touch(blk);
44
45    // Update last touch timestamp
46    blk->lastTouchTick = curTick();
47}
48
49void
50LRURP::reset(CacheBlk *blk)
51{
52    BaseReplacementPolicy::reset(blk);
53
54    // Set last touch timestamp
55    blk->lastTouchTick = blk->tickInserted;
56}
57
58CacheBlk*
59LRURP::getVictim(const ReplacementCandidates& candidates)
60{
61    // There must be at least one replacement candidate
62    assert(candidates.size() > 0);
63
64    // Visit all candidates to find victim
65    CacheBlk* blk = candidates[0];
66    for (const auto& candidate : candidates) {
67        // Stop iteration if found an invalid block
68        if (!candidate->isValid()) {
69            blk = candidate;
70            break;
71        // Update victim block if necessary
72        } else if (candidate->lastTouchTick < blk->lastTouchTick) {
73            blk = candidate;
74        }
75    }
76
77    DPRINTF(CacheRepl, "set %x, way %x: selecting blk for replacement\n",
78            blk->set, blk->way);
79
80    return blk;
81}
82
83LRURP*
84LRURPParams::create()
85{
86    return new LRURP(this);
87}
88