queue.hh revision 11377:a06a4debe272 
1/*
2 * Copyright (c) 2012-2013, 2015-2016 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
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: Erik Hallnor
41 *          Andreas Sandberg
42 *          Andreas Hansson
43 */
44
45/** @file
46 * Declaration of a high-level queue structure
47 */
48
49#ifndef __MEM_CACHE_QUEUE_HH__
50#define __MEM_CACHE_QUEUE_HH__
51
52#include <cassert>
53
54#include "base/trace.hh"
55#include "debug/Drain.hh"
56#include "mem/cache/queue_entry.hh"
57#include "sim/drain.hh"
58
59/**
60 * A high-level queue interface, to be used by both the MSHR queue and
61 * the write buffer.
62 */
63template<class Entry>
64class Queue : public Drainable
65{
66  protected:
67    /** Local label (for functional print requests) */
68    const std::string label;
69
70    /**
71     * The total number of entries in this queue. This number is set
72     * as the number of entries requested plus any reserve. This
73     * allows for the same number of effective entries while still
74     * maintaining an overflow reserve.
75     */
76    const int numEntries;
77
78    /**
79     * The number of entries to hold as a temporary overflow
80     * space. This is used to allow temporary overflow of the number
81     * of entries as we only check the full condition under certain
82     * conditions.
83     */
84    const int numReserve;
85
86    /**  Actual storage. */
87    std::vector<Entry> entries;
88    /** Holds pointers to all allocated entries. */
89    typename Entry::List allocatedList;
90    /** Holds pointers to entries that haven't been sent downstream. */
91    typename Entry::List readyList;
92    /** Holds non allocated entries. */
93    typename Entry::List freeList;
94
95    typename Entry::Iterator addToReadyList(Entry* entry)
96    {
97        if (readyList.empty() ||
98            readyList.back()->readyTime <= entry->readyTime) {
99            return readyList.insert(readyList.end(), entry);
100        }
101
102        for (auto i = readyList.begin(); i != readyList.end(); ++i) {
103            if ((*i)->readyTime > entry->readyTime) {
104                return readyList.insert(i, entry);
105            }
106        }
107        assert(false);
108        return readyList.end();  // keep stupid compilers happy
109    }
110
111    /** The number of entries that are in service. */
112    int _numInService;
113
114    /** The number of currently allocated entries. */
115    int allocated;
116
117  public:
118
119    /**
120     * Create a queue with a given number of entries.
121     *
122     * @param num_entries The number of entries in this queue.
123     * @param reserve The extra overflow entries needed.
124     */
125    Queue(const std::string &_label, int num_entries, int reserve) :
126        label(_label), numEntries(num_entries + reserve),
127        numReserve(reserve), entries(numEntries), _numInService(0),
128        allocated(0)
129    {
130        for (int i = 0; i < numEntries; ++i) {
131            freeList.push_back(&entries[i]);
132        }
133    }
134
135    bool isEmpty() const
136    {
137        return allocated == 0;
138    }
139
140    bool isFull() const
141    {
142        return (allocated >= numEntries - numReserve);
143    }
144
145    int numInService() const
146    {
147        return _numInService;
148    }
149
150    /**
151     * Find the first WriteQueueEntry that matches the provided address.
152     * @param blk_addr The block address to find.
153     * @param is_secure True if the target memory space is secure.
154     * @return Pointer to the matching WriteQueueEntry, null if not found.
155     */
156    Entry* findMatch(Addr blk_addr, bool is_secure) const
157    {
158        for (const auto& entry : allocatedList) {
159            // we ignore any entries allocated for uncacheable
160            // accesses and simply ignore them when matching, in the
161            // cache we never check for matches when adding new
162            // uncacheable entries, and we do not want normal
163            // cacheable accesses being added to an WriteQueueEntry
164            // serving an uncacheable access
165            if (!entry->isUncacheable() && entry->blkAddr == blk_addr &&
166                entry->isSecure == is_secure) {
167                return entry;
168            }
169        }
170        return nullptr;
171    }
172
173    bool checkFunctional(PacketPtr pkt, Addr blk_addr)
174    {
175        pkt->pushLabel(label);
176        for (const auto& entry : allocatedList) {
177            if (entry->blkAddr == blk_addr && entry->checkFunctional(pkt)) {
178                pkt->popLabel();
179                return true;
180            }
181        }
182        pkt->popLabel();
183        return false;
184    }
185
186    /**
187     * Find any pending requests that overlap the given request.
188     * @param blk_addr Block address.
189     * @param is_secure True if the target memory space is secure.
190     * @return A pointer to the earliest matching WriteQueueEntry.
191     */
192    Entry* findPending(Addr blk_addr, bool is_secure) const
193    {
194        for (const auto& entry : readyList) {
195            if (entry->blkAddr == blk_addr && entry->isSecure == is_secure) {
196                return entry;
197            }
198        }
199        return nullptr;
200    }
201
202    /**
203     * Returns the WriteQueueEntry at the head of the readyList.
204     * @return The next request to service.
205     */
206    Entry* getNext() const
207    {
208        if (readyList.empty() || readyList.front()->readyTime > curTick()) {
209            return NULL;
210        }
211        return readyList.front();
212    }
213
214    Tick nextReadyTime() const
215    {
216        return readyList.empty() ? MaxTick : readyList.front()->readyTime;
217    }
218
219    /**
220     * Removes the given entry from the queue. This places the entry
221     * on the free list.
222     *
223     * @param entry
224     */
225    void deallocate(Entry *entry)
226    {
227        allocatedList.erase(entry->allocIter);
228        freeList.push_front(entry);
229        allocated--;
230        if (entry->inService) {
231            _numInService--;
232        } else {
233            readyList.erase(entry->readyIter);
234        }
235        entry->deallocate();
236        if (drainState() == DrainState::Draining && allocated == 0) {
237            // Notify the drain manager that we have completed
238            // draining if there are no other outstanding requests in
239            // this queue.
240            DPRINTF(Drain, "Queue now empty, signalling drained\n");
241            signalDrainDone();
242        }
243    }
244
245    DrainState drain() override
246    {
247        return allocated == 0 ? DrainState::Drained : DrainState::Draining;
248    }
249};
250
251#endif //__MEM_CACHE_QUEUE_HH__
252