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 Re-Reference Interval Prediction replacement policy.
34 *
35 * Not-Recently Used (NRU) is an approximation of LRU that uses a single bit
36 * to determine if an entry is going to be re-referenced in the near or distant
37 * future.
38 *
39 * Re-Reference Interval Prediction (RRIP) is an extension of NRU that uses a
40 * re-reference prediction value to determine if entries are going to be re-
41 * used in the near future or not.
42 *
43 * The higher the value of the RRPV, the more distant the entry is from its
44 * next access.
45 *
46 * Bimodal Re-Reference Interval Prediction (BRRIP) is an extension of RRIP
47 * that has a probability of not inserting entries as the LRU. This probability
48 * is controlled by the bimodal throtle parameter (btp).
49 *
50 * From the original paper, this implementation of RRIP is also called
51 * Static RRIP (SRRIP), as it always inserts entries with the same RRPV.
52 */
53
54#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_BRRIP_RP_HH__
55#define __MEM_CACHE_REPLACEMENT_POLICIES_BRRIP_RP_HH__
56
| 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 Re-Reference Interval Prediction replacement policy.
34 *
35 * Not-Recently Used (NRU) is an approximation of LRU that uses a single bit
36 * to determine if an entry is going to be re-referenced in the near or distant
37 * future.
38 *
39 * Re-Reference Interval Prediction (RRIP) is an extension of NRU that uses a
40 * re-reference prediction value to determine if entries are going to be re-
41 * used in the near future or not.
42 *
43 * The higher the value of the RRPV, the more distant the entry is from its
44 * next access.
45 *
46 * Bimodal Re-Reference Interval Prediction (BRRIP) is an extension of RRIP
47 * that has a probability of not inserting entries as the LRU. This probability
48 * is controlled by the bimodal throtle parameter (btp).
49 *
50 * From the original paper, this implementation of RRIP is also called
51 * Static RRIP (SRRIP), as it always inserts entries with the same RRPV.
52 */
53
54#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_BRRIP_RP_HH__
55#define __MEM_CACHE_REPLACEMENT_POLICIES_BRRIP_RP_HH__
56
|
| 57#include "base/sat_counter.hh"
|
57#include "mem/cache/replacement_policies/base.hh"
58
59struct BRRIPRPParams;
60
61class BRRIPRP : public BaseReplacementPolicy
62{
63 protected:
64 /** BRRIP-specific implementation of replacement data. */
65 struct BRRIPReplData : ReplacementData
66 {
67 /**
68 * Re-Reference Interval Prediction Value.
69 * Some values have specific names (according to the paper):
70 * 0 -> near-immediate re-rereference interval
71 * max_RRPV-1 -> long re-rereference interval
72 * max_RRPV -> distant re-rereference interval
| 58#include "mem/cache/replacement_policies/base.hh"
59
60struct BRRIPRPParams;
61
62class BRRIPRP : public BaseReplacementPolicy
63{
64 protected:
65 /** BRRIP-specific implementation of replacement data. */
66 struct BRRIPReplData : ReplacementData
67 {
68 /**
69 * Re-Reference Interval Prediction Value.
70 * Some values have specific names (according to the paper):
71 * 0 -> near-immediate re-rereference interval
72 * max_RRPV-1 -> long re-rereference interval
73 * max_RRPV -> distant re-rereference interval
|
73 * A value equal to max_RRPV + 1 indicates an invalid entry.
| |
74 */
| 74 */
|
75 int rrpv;
| 75 SatCounter rrpv;
|
76
| 76
|
| 77 /** Whether the entry is valid. */
78 bool valid;
79
|
77 /**
78 * Default constructor. Invalidate data.
79 */
| 80 /**
81 * Default constructor. Invalidate data.
82 */
|
80 BRRIPReplData(const int max_RRPV) : rrpv(max_RRPV + 1) {}
| 83 BRRIPReplData(const int num_bits)
84 : rrpv(num_bits), valid(false)
85 {
86 }
|
81 };
82
83 /**
| 87 };
88
89 /**
|
84 * Maximum Re-Reference Prediction Value possible. An entry with this
85 * value as the rrpv has the longest possible re-reference interval,
86 * that is, it is likely not to be used in the near future, and is
87 * among the best eviction candidates.
88 * A maxRRPV of 1 implies in a NRU.
| 90 * Number of RRPV bits. An entry that saturates its RRPV has the longest
91 * possible re-reference interval, that is, it is likely not to be used
92 * in the near future, and is among the best eviction candidates.
93 * A maximum RRPV of 1 implies in a NRU.
|
89 */
| 94 */
|
90 const int maxRRPV;
| 95 const unsigned numRRPVBits;
|
91
92 /**
93 * The hit priority (HP) policy replaces entries that do not receive cache
94 * hits over any cache entry that receives a hit, while the frequency
95 * priority (FP) policy replaces infrequently re-referenced entries.
96 */
97 const bool hitPriority;
98
99 /**
100 * Bimodal throtle parameter. Value in the range [0,100] used to decide
101 * if a new entry is inserted with long or distant re-reference.
102 */
103 const unsigned btp;
104
105 public:
106 /** Convenience typedef. */
107 typedef BRRIPRPParams Params;
108
109 /**
110 * Construct and initiliaze this replacement policy.
111 */
112 BRRIPRP(const Params *p);
113
114 /**
115 * Destructor.
116 */
117 ~BRRIPRP() {}
118
119 /**
120 * Invalidate replacement data to set it as the next probable victim.
121 * Set RRPV as the the most distant re-reference.
122 *
123 * @param replacement_data Replacement data to be invalidated.
124 */
125 void invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
126 const override;
127
128 /**
129 * Touch an entry to update its replacement data.
130 *
131 * @param replacement_data Replacement data to be touched.
132 */
133 void touch(const std::shared_ptr<ReplacementData>& replacement_data) const
134 override;
135
136 /**
137 * Reset replacement data. Used when an entry is inserted.
138 * Set RRPV according to the insertion policy used.
139 *
140 * @param replacement_data Replacement data to be reset.
141 */
142 void reset(const std::shared_ptr<ReplacementData>& replacement_data) const
143 override;
144
145 /**
146 * Find replacement victim using rrpv.
147 *
148 * @param cands Replacement candidates, selected by indexing policy.
149 * @return Replacement entry to be replaced.
150 */
151 ReplaceableEntry* getVictim(const ReplacementCandidates& candidates) const
152 override;
153
154 /**
155 * Instantiate a replacement data entry.
156 *
157 * @return A shared pointer to the new replacement data.
158 */
159 std::shared_ptr<ReplacementData> instantiateEntry() override;
160};
161
162#endif // __MEM_CACHE_REPLACEMENT_POLICIES_BRRIP_RP_HH__
| 96
97 /**
98 * The hit priority (HP) policy replaces entries that do not receive cache
99 * hits over any cache entry that receives a hit, while the frequency
100 * priority (FP) policy replaces infrequently re-referenced entries.
101 */
102 const bool hitPriority;
103
104 /**
105 * Bimodal throtle parameter. Value in the range [0,100] used to decide
106 * if a new entry is inserted with long or distant re-reference.
107 */
108 const unsigned btp;
109
110 public:
111 /** Convenience typedef. */
112 typedef BRRIPRPParams Params;
113
114 /**
115 * Construct and initiliaze this replacement policy.
116 */
117 BRRIPRP(const Params *p);
118
119 /**
120 * Destructor.
121 */
122 ~BRRIPRP() {}
123
124 /**
125 * Invalidate replacement data to set it as the next probable victim.
126 * Set RRPV as the the most distant re-reference.
127 *
128 * @param replacement_data Replacement data to be invalidated.
129 */
130 void invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
131 const override;
132
133 /**
134 * Touch an entry to update its replacement data.
135 *
136 * @param replacement_data Replacement data to be touched.
137 */
138 void touch(const std::shared_ptr<ReplacementData>& replacement_data) const
139 override;
140
141 /**
142 * Reset replacement data. Used when an entry is inserted.
143 * Set RRPV according to the insertion policy used.
144 *
145 * @param replacement_data Replacement data to be reset.
146 */
147 void reset(const std::shared_ptr<ReplacementData>& replacement_data) const
148 override;
149
150 /**
151 * Find replacement victim using rrpv.
152 *
153 * @param cands Replacement candidates, selected by indexing policy.
154 * @return Replacement entry to be replaced.
155 */
156 ReplaceableEntry* getVictim(const ReplacementCandidates& candidates) const
157 override;
158
159 /**
160 * Instantiate a replacement data entry.
161 *
162 * @return A shared pointer to the new replacement data.
163 */
164 std::shared_ptr<ReplacementData> instantiateEntry() override;
165};
166
167#endif // __MEM_CACHE_REPLACEMENT_POLICIES_BRRIP_RP_HH__
|