LRUPolicy.hh revision 10314:94b6b28fc968 
1/*
2 * Copyright (c) 2007 Mark D. Hill and David A. Wood
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
29#ifndef __MEM_RUBY_SYSTEM_LRUPOLICY_HH__
30#define __MEM_RUBY_SYSTEM_LRUPOLICY_HH__
31
32#include "mem/ruby/structures/AbstractReplacementPolicy.hh"
33
34/* Simple true LRU replacement policy */
35
36class LRUPolicy : public AbstractReplacementPolicy
37{
38  public:
39    LRUPolicy(int64 num_sets, int64 assoc);
40    ~LRUPolicy();
41
42    void touch(int64 set, int64 way, Tick time);
43    int64 getVictim(int64 set) const;
44};
45
46inline
47LRUPolicy::LRUPolicy(int64 num_sets, int64 assoc)
48    : AbstractReplacementPolicy(num_sets, assoc)
49{
50}
51
52inline
53LRUPolicy::~LRUPolicy()
54{
55}
56
57inline void
58LRUPolicy::touch(int64 set, int64 index, Tick time)
59{
60    assert(index >= 0 && index < m_assoc);
61    assert(set >= 0 && set < m_num_sets);
62
63    m_last_ref_ptr[set][index] = time;
64}
65
66inline int64
67LRUPolicy::getVictim(int64 set) const
68{
69    //  assert(m_assoc != 0);
70    Tick time, smallest_time;
71    int64 smallest_index;
72
73    smallest_index = 0;
74    smallest_time = m_last_ref_ptr[set][0];
75
76    for (unsigned i = 0; i < m_assoc; i++) {
77        time = m_last_ref_ptr[set][i];
78        // assert(m_cache[cacheSet][i].m_Permission !=
79        //     AccessPermission_NotPresent);
80
81        if (time < smallest_time) {
82            smallest_index = i;
83            smallest_time = time;
84        }
85    }
86
87    //  DEBUG_EXPR(CACHE_COMP, MedPrio, cacheSet);
88    //  DEBUG_EXPR(CACHE_COMP, MedPrio, smallest_index);
89    //  DEBUG_EXPR(CACHE_COMP, MedPrio, m_cache[cacheSet][smallest_index]);
90    //  DEBUG_EXPR(CACHE_COMP, MedPrio, *this);
91
92    return smallest_index;
93}
94
95#endif // __MEM_RUBY_SYSTEM_LRUPOLICY_HH__
96