stride.hh revision 13425 
1/*
2 * Copyright (c) 2012-2013, 2015 ARM Limited
3 * All rights reserved
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder.  You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2005 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Ron Dreslinski
41 */
42
43/**
44 * @file
45 * Describes a strided prefetcher.
46 */
47
48#ifndef __MEM_CACHE_PREFETCH_STRIDE_HH__
49#define __MEM_CACHE_PREFETCH_STRIDE_HH__
50
51#include <string>
52#include <unordered_map>
53#include <vector>
54
55#include "base/types.hh"
56#include "mem/cache/prefetch/queued.hh"
57#include "mem/packet.hh"
58
59struct StridePrefetcherParams;
60
61class StridePrefetcher : public QueuedPrefetcher
62{
63  protected:
64    const int maxConf;
65    const int threshConf;
66    const int minConf;
67    const int startConf;
68
69    const int pcTableAssoc;
70    const int pcTableSets;
71
72    const bool useMasterId;
73
74    const int degree;
75
76    struct StrideEntry
77    {
78        StrideEntry() : instAddr(0), lastAddr(0), isSecure(false), stride(0),
79                        confidence(0)
80        { }
81
82        Addr instAddr;
83        Addr lastAddr;
84        bool isSecure;
85        int stride;
86        int confidence;
87    };
88
89    class PCTable
90    {
91      public:
92        /**
93         * Default constructor. Create a table with given parameters.
94         *
95         * @param assoc Associativity of the table.
96         * @param sets Number of sets in the table.
97         * @param name Name of the prefetcher.
98         */
99        PCTable(int assoc, int sets, const std::string name);
100
101        /**
102         * Default destructor.
103         */
104        ~PCTable();
105
106        /**
107         * Search for an entry in the pc table.
108         *
109         * @param pc The PC to look for.
110         * @param is_secure True if the target memory space is secure.
111         * @return Pointer to the entry.
112         */
113        StrideEntry* findEntry(Addr pc, bool is_secure);
114
115        /**
116         * Find a replacement victim to make room for given PC.
117         *
118         * @param pc The PC value.
119         * @return The victimized entry.
120         */
121        StrideEntry* findVictim(Addr pc);
122
123      private:
124        const std::string name() {return _name; }
125        const int pcTableAssoc;
126        const int pcTableSets;
127        const std::string _name;
128        std::vector<std::vector<StrideEntry>> entries;
129
130        /**
131         * PC hashing function to index sets in the table.
132         *
133         * @param pc The PC value.
134         * @return The set to which this PC maps.
135         */
136        Addr pcHash(Addr pc) const;
137    };
138    std::unordered_map<int, PCTable> pcTables;
139
140    /**
141     * Try to find a table of entries for the given context. If none is
142     * found, a new table is created.
143     *
144     * @param context The context to be searched for.
145     * @return The table corresponding to the given context.
146     */
147    PCTable* findTable(int context);
148
149    /**
150     * Create a PC table for the given context.
151     *
152     * @param context The context of the new PC table.
153     * @return The new PC table
154     */
155    PCTable* allocateNewContext(int context);
156
157  public:
158    StridePrefetcher(const StridePrefetcherParams *p);
159
160    void calculatePrefetch(const PacketPtr &pkt,
161                           std::vector<AddrPriority> &addresses) override;
162};
163
164#endif // __MEM_CACHE_PREFETCH_STRIDE_HH__
165