mshr_queue.hh revision 10192 
1/*
2 * Copyright (c) 2012-2013 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) 2003-2005 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
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38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Erik Hallnor
41 *          Andreas Sandberg
42 */
43
44/** @file
45 * Declaration of a structure to manage MSHRs.
46 */
47
48#ifndef __MEM__CACHE__MISS__MSHR_QUEUE_HH__
49#define __MEM__CACHE__MISS__MSHR_QUEUE_HH__
50
51#include <vector>
52
53#include "mem/cache/mshr.hh"
54#include "mem/packet.hh"
55#include "sim/drain.hh"
56
57/**
58 * A Class for maintaining a list of pending and allocated memory requests.
59 */
60class MSHRQueue : public Drainable
61{
62  private:
63    /** Local label (for functional print requests) */
64    const std::string label;
65
66    // Parameters
67    /**
68     * The total number of entries in this queue. This number is set as the
69     * number of entries requested plus (numReserve - 1). This allows for
70     * the same number of effective entries while still maintaining the reserve.
71     */
72    const int numEntries;
73
74    /**
75     * The number of entries to hold in reserve. This is needed because copy
76     * operations can allocate upto 4 entries at one time.
77     */
78    const int numReserve;
79
80    /**  MSHR storage. */
81    std::vector<MSHR> registers;
82    /** Holds pointers to all allocated entries. */
83    MSHR::List allocatedList;
84    /** Holds pointers to entries that haven't been sent to the bus. */
85    MSHR::List readyList;
86    /** Holds non allocated entries. */
87    MSHR::List freeList;
88
89    /** Drain manager to inform of a completed drain */
90    DrainManager *drainManager;
91
92    MSHR::Iterator addToReadyList(MSHR *mshr);
93
94
95  public:
96    /** The number of allocated entries. */
97    int allocated;
98    /** The number of entries that have been forwarded to the bus. */
99    int inServiceEntries;
100    /** The index of this queue within the cache (MSHR queue vs. write
101     * buffer). */
102    const int index;
103
104    /**
105     * Create a queue with a given number of entries.
106     * @param num_entrys The number of entries in this queue.
107     * @param reserve The minimum number of entries needed to satisfy
108     * any access.
109     */
110    MSHRQueue(const std::string &_label, int num_entries, int reserve,
111              int index);
112
113    /**
114     * Find the first MSHR that matches the provided address.
115     * @param addr The address to find.
116     * @param is_secure True if the target memory space is secure.
117     * @return Pointer to the matching MSHR, null if not found.
118     */
119    MSHR *findMatch(Addr addr, bool is_secure) const;
120
121    /**
122     * Find and return all the matching entries in the provided vector.
123     * @param addr The address to find.
124     * @param is_secure True if the target memory space is secure.
125     * @param matches The vector to return pointers to the matching entries.
126     * @return True if any matches are found, false otherwise.
127     * @todo Typedef the vector??
128     */
129    bool findMatches(Addr addr, bool is_secure,
130                     std::vector<MSHR*>& matches) const;
131
132    /**
133     * Find any pending requests that overlap the given request.
134     * @param pkt The request to find.
135     * @param is_secure True if the target memory space is secure.
136     * @return A pointer to the earliest matching MSHR.
137     */
138    MSHR *findPending(Addr addr, int size, bool is_secure) const;
139
140    bool checkFunctional(PacketPtr pkt, Addr blk_addr);
141
142    /**
143     * Allocates a new MSHR for the request and size. This places the request
144     * as the first target in the MSHR.
145     * @param pkt The request to handle.
146     * @param size The number in bytes to fetch from memory.
147     * @return The a pointer to the MSHR allocated.
148     *
149     * @pre There are free entries.
150     */
151    MSHR *allocate(Addr addr, int size, PacketPtr &pkt,
152                   Tick when, Counter order);
153
154    /**
155     * Removes the given MSHR from the queue. This places the MSHR on the
156     * free list.
157     * @param mshr
158     */
159    void deallocate(MSHR *mshr);
160
161    /**
162     * Remove a MSHR from the queue. Returns an iterator into the
163     * allocatedList for faster squash implementation.
164     * @param mshr The MSHR to remove.
165     * @return An iterator to the next entry in the allocatedList.
166     */
167    MSHR::Iterator deallocateOne(MSHR *mshr);
168
169    /**
170     * Moves the MSHR to the front of the pending list if it is not
171     * in service.
172     * @param mshr The entry to move.
173     */
174    void moveToFront(MSHR *mshr);
175
176    /**
177     * Mark the given MSHR as in service. This removes the MSHR from the
178     * readyList. Deallocates the MSHR if it does not expect a response.
179     * @param mshr The MSHR to mark in service.
180     */
181    void markInService(MSHR *mshr, PacketPtr pkt);
182
183    /**
184     * Mark an in service entry as pending, used to resend a request.
185     * @param mshr The MSHR to resend.
186     */
187    void markPending(MSHR *mshr);
188
189    /**
190     * Squash outstanding requests with the given thread number. If a request
191     * is in service, just squashes the targets.
192     * @param threadNum The thread to squash.
193     */
194    void squash(int threadNum);
195
196    /**
197     * Deallocate top target, possibly freeing the MSHR
198     * @return if MSHR queue is no longer full
199     */
200    bool forceDeallocateTarget(MSHR *mshr);
201
202    /**
203     * Returns true if the pending list is not empty.
204     * @return True if there are outstanding requests.
205     */
206    bool havePending() const
207    {
208        return !readyList.empty();
209    }
210
211    /**
212     * Returns true if there are no free entries.
213     * @return True if this queue is full.
214     */
215    bool isFull() const
216    {
217        return (allocated > numEntries - numReserve);
218    }
219
220    /**
221     * Returns the MSHR at the head of the readyList.
222     * @return The next request to service.
223     */
224    MSHR *getNextMSHR() const
225    {
226        if (readyList.empty() || readyList.front()->readyTime > curTick()) {
227            return NULL;
228        }
229        return readyList.front();
230    }
231
232    Tick nextMSHRReadyTime() const
233    {
234        return readyList.empty() ? MaxTick : readyList.front()->readyTime;
235    }
236
237    unsigned int drain(DrainManager *dm);
238};
239
240#endif //__MEM__CACHE__MISS__MSHR_QUEUE_HH__
241