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 #include <type_traits>
  55
  56 #include "base/logging.hh"
  57 #include "base/trace.hh"
  58 #include "base/types.hh"
  59 #include "debug/Drain.hh"
  60 #include "mem/cache/queue_entry.hh"
  61 #include "mem/packet.hh"
  62 #include "sim/core.hh"
  63 #include "sim/drain.hh"
  64
  65 /**
  66  * A high-level queue interface, to be used by both the MSHR queue and
  67  * the write buffer.
  68  */
  69 template<class Entry>
  70 class Queue : public Drainable
  71 {
  72     static_assert(std::is_base_of<QueueEntry, Entry>::value,
  73         "Entry must be derived from QueueEntry");
  74
  75   protected:
  76     /** Local label (for functional print requests) */
  77     const std::string label;
  78
  79     /**
  80      * The total number of entries in this queue. This number is set
  81      * as the number of entries requested plus any reserve. This
  82      * allows for the same number of effective entries while still
  83      * maintaining an overflow reserve.
  84      */
  85     const int numEntries;
  86
  87     /**
  88      * The number of entries to hold as a temporary overflow
  89      * space. This is used to allow temporary overflow of the number
  90      * of entries as we only check the full condition under certain
  91      * conditions.
  92      */
  93     const int numReserve;
  94
  95     /**  Actual storage. */
  96     std::vector<Entry> entries;
  97     /** Holds pointers to all allocated entries. */
  98     typename Entry::List allocatedList;
  99     /** Holds pointers to entries that haven't been sent downstream. */
 100     typename Entry::List readyList;
 101     /** Holds non allocated entries. */
 102     typename Entry::List freeList;
 103
 104     typename Entry::Iterator addToReadyList(Entry* entry)
 105     {
 106         if (readyList.empty() ||
 107             readyList.back()->readyTime <= entry->readyTime) {
 108             return readyList.insert(readyList.end(), entry);
 109         }
 110
 111         for (auto i = readyList.begin(); i != readyList.end(); ++i) {
 112             if ((*i)->readyTime > entry->readyTime) {
 113                 return readyList.insert(i, entry);
 114             }
 115         }
 116         panic("Failed to add to ready list.");
 117     }
 118
 119     /** The number of entries that are in service. */
 120     int _numInService;
 121
 122     /** The number of currently allocated entries. */
 123     int allocated;
 124
 125   public:
 126
 127     /**
 128      * Create a queue with a given number of entries.
 129      *
 130      * @param num_entries The number of entries in this queue.
 131      * @param reserve The extra overflow entries needed.
 132      */
 133     Queue(const std::string &_label, int num_entries, int reserve) :
 134         label(_label), numEntries(num_entries + reserve),
 135         numReserve(reserve), entries(numEntries), _numInService(0),
 136         allocated(0)
 137     {
 138         for (int i = 0; i < numEntries; ++i) {
 139             freeList.push_back(&entries[i]);
 140         }
 141     }
 142
 143     bool isEmpty() const
 144     {
 145         return allocated == 0;
 146     }
 147
 148     bool isFull() const
 149     {
 150         return (allocated >= numEntries - numReserve);
 151     }
 152
 153     int numInService() const
 154     {
 155         return _numInService;
 156     }
 157
 158     /**
 159      * Find the first entry that matches the provided address.
 160      *
 161      * @param blk_addr The block address to find.
 162      * @param is_secure True if the target memory space is secure.
 163      * @param ignore_uncacheable Should uncacheables be ignored or not
 164      * @return Pointer to the matching WriteQueueEntry, null if not found.
 165      */
 166     Entry* findMatch(Addr blk_addr, bool is_secure,
 167                      bool ignore_uncacheable = true) const
 168     {
 169         for (const auto& entry : allocatedList) {
 170             // we ignore any entries allocated for uncacheable
 171             // accesses and simply ignore them when matching, in the
 172             // cache we never check for matches when adding new
 173             // uncacheable entries, and we do not want normal
 174             // cacheable accesses being added to an WriteQueueEntry
 175             // serving an uncacheable access
 176             if (!(ignore_uncacheable && entry->isUncacheable()) &&
 177                 entry->matchBlockAddr(blk_addr, is_secure)) {
 178                 return entry;
 179             }
 180         }
 181         return nullptr;
 182     }
 183
 184     bool trySatisfyFunctional(PacketPtr pkt)
 185     {
 186         pkt->pushLabel(label);
 187         for (const auto& entry : allocatedList) {
 188             if (entry->matchBlockAddr(pkt) &&
 189                 entry->trySatisfyFunctional(pkt)) {
 190                 pkt->popLabel();
 191                 return true;
 192             }
 193         }
 194         pkt->popLabel();
 195         return false;
 196     }
 197
 198     /**
 199      * Find any pending requests that overlap the given request of a
 200      * different queue.
 201      *
 202      * @param entry The entry to be compared against.
 203      * @return A pointer to the earliest matching entry.
 204      */
 205     Entry* findPending(const QueueEntry* entry) const
 206     {
 207         for (const auto& ready_entry : readyList) {
 208             if (ready_entry->conflictAddr(entry)) {
 209                 return ready_entry;
 210             }
 211         }
 212         return nullptr;
 213     }
 214
 215     /**
 216      * Returns the WriteQueueEntry at the head of the readyList.
 217      * @return The next request to service.
 218      */
 219     Entry* getNext() const
 220     {
 221         if (readyList.empty() || readyList.front()->readyTime > curTick()) {
 222             return nullptr;
 223         }
 224         return readyList.front();
 225     }
 226
 227     Tick nextReadyTime() const
 228     {
 229         return readyList.empty() ? MaxTick : readyList.front()->readyTime;
 230     }
 231
 232     /**
 233      * Removes the given entry from the queue. This places the entry
 234      * on the free list.
 235      *
 236      * @param entry
 237      */
 238     void deallocate(Entry *entry)
 239     {
 240         allocatedList.erase(entry->allocIter);
 241         freeList.push_front(entry);
 242         allocated--;
 243         if (entry->inService) {
 244             _numInService--;
 245         } else {
 246             readyList.erase(entry->readyIter);
 247         }
 248         entry->deallocate();
 249         if (drainState() == DrainState::Draining && allocated == 0) {
 250             // Notify the drain manager that we have completed
 251             // draining if there are no other outstanding requests in
 252             // this queue.
 253             DPRINTF(Drain, "Queue now empty, signalling drained\n");
 254             signalDrainDone();
 255         }
 256     }
 257
 258     DrainState drain() override
 259     {
 260         return allocated == 0 ? DrainState::Drained : DrainState::Draining;
 261     }
 262 };
 263
 264 #endif //__MEM_CACHE_QUEUE_HH__