mshr_queue.hh revision 8229 
1/*
2 * Copyright (c) 2003-2005 The Regents of The University of Michigan
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: Erik Hallnor
29 */
30
31/** @file
32 * Declaration of a structure to manage MSHRs.
33 */
34
35#ifndef __MEM__CACHE__MISS__MSHR_QUEUE_HH__
36#define __MEM__CACHE__MISS__MSHR_QUEUE_HH__
37
38#include <vector>
39
40#include "mem/cache/mshr.hh"
41#include "mem/packet.hh"
42
43/**
44 * A Class for maintaining a list of pending and allocated memory requests.
45 */
46class MSHRQueue
47{
48  private:
49    /** Local label (for functional print requests) */
50    const std::string label;
51
52    /**  MSHR storage. */
53    MSHR *registers;
54    /** Holds pointers to all allocated entries. */
55    MSHR::List allocatedList;
56    /** Holds pointers to entries that haven't been sent to the bus. */
57    MSHR::List readyList;
58    /** Holds non allocated entries. */
59    MSHR::List freeList;
60
61    // Parameters
62    /**
63     * The total number of entries in this queue. This number is set as the
64     * number of entries requested plus (numReserve - 1). This allows for
65     * the same number of effective entries while still maintaining the reserve.
66     */
67    const int numEntries;
68
69    /**
70     * The number of entries to hold in reserve. This is needed because copy
71     * operations can allocate upto 4 entries at one time.
72     */
73    const int numReserve;
74
75    MSHR::Iterator addToReadyList(MSHR *mshr);
76
77
78  public:
79    /** The number of allocated entries. */
80    int allocated;
81    /** The number of entries that have been forwarded to the bus. */
82    int inServiceEntries;
83    /** The index of this queue within the cache (MSHR queue vs. write
84     * buffer). */
85    const int index;
86
87    /**
88     * Create a queue with a given number of entries.
89     * @param num_entrys The number of entries in this queue.
90     * @param reserve The minimum number of entries needed to satisfy
91     * any access.
92     */
93    MSHRQueue(const std::string &_label, int num_entries, int reserve,
94              int index);
95
96    /** Destructor */
97    ~MSHRQueue();
98
99    /**
100     * Find the first MSHR that matches the provided address.
101     * @param addr The address to find.
102     * @return Pointer to the matching MSHR, null if not found.
103     */
104    MSHR *findMatch(Addr addr) const;
105
106    /**
107     * Find and return all the matching entries in the provided vector.
108     * @param addr The address to find.
109     * @param matches The vector to return pointers to the matching entries.
110     * @return True if any matches are found, false otherwise.
111     * @todo Typedef the vector??
112     */
113    bool findMatches(Addr addr, std::vector<MSHR*>& matches) const;
114
115    /**
116     * Find any pending requests that overlap the given request.
117     * @param pkt The request to find.
118     * @return A pointer to the earliest matching MSHR.
119     */
120    MSHR *findPending(Addr addr, int size) const;
121
122    bool checkFunctional(PacketPtr pkt, Addr blk_addr);
123
124    /**
125     * Allocates a new MSHR for the request and size. This places the request
126     * as the first target in the MSHR.
127     * @param pkt The request to handle.
128     * @param size The number in bytes to fetch from memory.
129     * @return The a pointer to the MSHR allocated.
130     *
131     * @pre There are free entries.
132     */
133    MSHR *allocate(Addr addr, int size, PacketPtr &pkt,
134                   Tick when, Counter order);
135
136    /**
137     * Removes the given MSHR from the queue. This places the MSHR on the
138     * free list.
139     * @param mshr
140     */
141    void deallocate(MSHR *mshr);
142
143    /**
144     * Remove a MSHR from the queue. Returns an iterator into the
145     * allocatedList for faster squash implementation.
146     * @param mshr The MSHR to remove.
147     * @return An iterator to the next entry in the allocatedList.
148     */
149    MSHR::Iterator deallocateOne(MSHR *mshr);
150
151    /**
152     * Moves the MSHR to the front of the pending list if it is not
153     * in service.
154     * @param mshr The entry to move.
155     */
156    void moveToFront(MSHR *mshr);
157
158    /**
159     * Mark the given MSHR as in service. This removes the MSHR from the
160     * readyList. Deallocates the MSHR if it does not expect a response.
161     * @param mshr The MSHR to mark in service.
162     */
163    void markInService(MSHR *mshr, PacketPtr pkt);
164
165    /**
166     * Mark an in service entry as pending, used to resend a request.
167     * @param mshr The MSHR to resend.
168     */
169    void markPending(MSHR *mshr);
170
171    /**
172     * Squash outstanding requests with the given thread number. If a request
173     * is in service, just squashes the targets.
174     * @param threadNum The thread to squash.
175     */
176    void squash(int threadNum);
177
178    /**
179     * Returns true if the pending list is not empty.
180     * @return True if there are outstanding requests.
181     */
182    bool havePending() const
183    {
184        return !readyList.empty();
185    }
186
187    /**
188     * Returns true if there are no free entries.
189     * @return True if this queue is full.
190     */
191    bool isFull() const
192    {
193        return (allocated > numEntries - numReserve);
194    }
195
196    /**
197     * Returns the MSHR at the head of the readyList.
198     * @return The next request to service.
199     */
200    MSHR *getNextMSHR() const
201    {
202        if (readyList.empty() || readyList.front()->readyTime > curTick()) {
203            return NULL;
204        }
205        return readyList.front();
206    }
207
208    Tick nextMSHRReadyTime() const
209    {
210        return readyList.empty() ? MaxTick : readyList.front()->readyTime;
211    }
212};
213
214#endif //__MEM__CACHE__MISS__MSHR_QUEUE_HH__
215