src/mem/cache/queue.hh

   1 /*
   2  * Copyright (c) 2012-2013, 2015-2016, 2018 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 #include <string>
  54
  55 #include "base/trace.hh"
  56 #include "base/types.hh"
  57 #include "debug/Drain.hh"
  58 #include "mem/cache/queue_entry.hh"
  59 #include "mem/packet.hh"
  60 #include "sim/core.hh"
  61 #include "sim/drain.hh"
  62
  63 /**
  64  * A high-level queue interface, to be used by both the MSHR queue and
  65  * the write buffer.
  66  */
  67 template<class Entry>
  68 class Queue : public Drainable
  69 {
  70   protected:
  71     /** Local label (for functional print requests) */
  72     const std::string label;
  73
  74     /**
  75      * The total number of entries in this queue. This number is set
  76      * as the number of entries requested plus any reserve. This
  77      * allows for the same number of effective entries while still
  78      * maintaining an overflow reserve.
  79      */
  80     const int numEntries;
  81
  82     /**
  83      * The number of entries to hold as a temporary overflow
  84      * space. This is used to allow temporary overflow of the number
  85      * of entries as we only check the full condition under certain
  86      * conditions.
  87      */
  88     const int numReserve;
  89
  90     /**  Actual storage. */
  91     std::vector<Entry> entries;
  92     /** Holds pointers to all allocated entries. */
  93     typename Entry::List allocatedList;
  94     /** Holds pointers to entries that haven't been sent downstream. */
  95     typename Entry::List readyList;
  96     /** Holds non allocated entries. */
  97     typename Entry::List freeList;
  98
  99     typename Entry::Iterator addToReadyList(Entry* entry)
 100     {
 101         if (readyList.empty() ||
 102             readyList.back()->readyTime <= entry->readyTime) {
 103             return readyList.insert(readyList.end(), entry);
 104         }
 105
 106         for (auto i = readyList.begin(); i != readyList.end(); ++i) {
 107             if ((*i)->readyTime > entry->readyTime) {
 108                 return readyList.insert(i, entry);
 109             }
 110         }
 111         assert(false);
 112         return readyList.end();  // keep stupid compilers happy
 113     }
 114
 115     /** The number of entries that are in service. */
 116     int _numInService;
 117
 118     /** The number of currently allocated entries. */
 119     int allocated;
 120
 121   public:
 122
 123     /**
 124      * Create a queue with a given number of entries.
 125      *
 126      * @param num_entries The number of entries in this queue.
 127      * @param reserve The extra overflow entries needed.
 128      */
 129     Queue(const std::string &_label, int num_entries, int reserve) :
 130         label(_label), numEntries(num_entries + reserve),
 131         numReserve(reserve), entries(numEntries), _numInService(0),
 132         allocated(0)
 133     {
 134         for (int i = 0; i < numEntries; ++i) {
 135             freeList.push_back(&entries[i]);
 136         }
 137     }
 138
 139     bool isEmpty() const
 140     {
 141         return allocated == 0;
 142     }
 143
 144     bool isFull() const
 145     {
 146         return (allocated >= numEntries - numReserve);
 147     }
 148
 149     int numInService() const
 150     {
 151         return _numInService;
 152     }
 153
 154     /**
 155      * Find the first entry that matches the provided address.
 156      *
 157      * @param blk_addr The block address to find.
 158      * @param is_secure True if the target memory space is secure.
 159      * @param ignore_uncacheable Should uncacheables be ignored or not
 160      * @return Pointer to the matching WriteQueueEntry, null if not found.
 161      */
 162     Entry* findMatch(Addr blk_addr, bool is_secure,
 163                      bool ignore_uncacheable = true) const
 164     {
 165         for (const auto& entry : allocatedList) {
 166             // we ignore any entries allocated for uncacheable
 167             // accesses and simply ignore them when matching, in the
 168             // cache we never check for matches when adding new
 169             // uncacheable entries, and we do not want normal
 170             // cacheable accesses being added to an WriteQueueEntry
 171             // serving an uncacheable access
 172             if (!(ignore_uncacheable && entry->isUncacheable()) &&
 173                 entry->blkAddr == blk_addr && entry->isSecure == is_secure) {
 174                 return entry;
 175             }
 176         }
 177         return nullptr;
 178     }
 179
 180     bool checkFunctional(PacketPtr pkt, Addr blk_addr)
 181     {
 182         pkt->pushLabel(label);
 183         for (const auto& entry : allocatedList) {
 184             if (entry->blkAddr == blk_addr && entry->checkFunctional(pkt)) {
 185                 pkt->popLabel();
 186                 return true;
 187             }
 188         }
 189         pkt->popLabel();
 190         return false;
 191     }
 192
 193     /**
 194      * Find any pending requests that overlap the given request.
 195      * @param blk_addr Block address.
 196      * @param is_secure True if the target memory space is secure.
 197      * @return A pointer to the earliest matching WriteQueueEntry.
 198      */
 199     Entry* findPending(Addr blk_addr, bool is_secure) const
 200     {
 201         for (const auto& entry : readyList) {
 202             if (entry->blkAddr == blk_addr && entry->isSecure == is_secure) {
 203                 return entry;
 204             }
 205         }
 206         return nullptr;
 207     }
 208
 209     /**
 210      * Returns the WriteQueueEntry at the head of the readyList.
 211      * @return The next request to service.
 212      */
 213     Entry* getNext() const
 214     {
 215         if (readyList.empty() || readyList.front()->readyTime > curTick()) {
 216             return nullptr;
 217         }
 218         return readyList.front();
 219     }
 220
 221     Tick nextReadyTime() const
 222     {
 223         return readyList.empty() ? MaxTick : readyList.front()->readyTime;
 224     }
 225
 226     /**
 227      * Removes the given entry from the queue. This places the entry
 228      * on the free list.
 229      *
 230      * @param entry
 231      */
 232     void deallocate(Entry *entry)
 233     {
 234         allocatedList.erase(entry->allocIter);
 235         freeList.push_front(entry);
 236         allocated--;
 237         if (entry->inService) {
 238             _numInService--;
 239         } else {
 240             readyList.erase(entry->readyIter);
 241         }
 242         entry->deallocate();
 243         if (drainState() == DrainState::Draining && allocated == 0) {
 244             // Notify the drain manager that we have completed
 245             // draining if there are no other outstanding requests in
 246             // this queue.
 247             DPRINTF(Drain, "Queue now empty, signalling drained\n");
 248             signalDrainDone();
 249         }
 250     }
 251
 252     DrainState drain() override
 253     {
 254         return allocated == 0 ? DrainState::Drained : DrainState::Draining;
 255     }
 256 };
 257
 258 #endif //__MEM_CACHE_QUEUE_HH__