src/mem/cache/tags/split_lifo.hh

   1 /*
   2  * Copyright (c) 2004-2005 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: Lisa Hsu
  29  */
  30
  31 /**
  32  * @file
  33  * Declaration of a LIFO tag store usable in a partitioned cache.
  34  */
  35
  36 #ifndef __SPLIT_LIFO_HH__
  37 #define __SPLIT_LIFO_HH__
  38
  39 #include <list>
  40
  41 #include "mem/cache/cache_blk.hh" // base class
  42 #include "mem/cache/tags/split_blk.hh"
  43 #include "mem/packet.hh" // for inlined functions
  44 #include "base/hashmap.hh"
  45 #include <assert.h>
  46 #include "mem/cache/tags/base_tags.hh"
  47
  48 class BaseCache;
  49
  50 /**
  51  * A LIFO set of cache blks
  52  */
  53 class LIFOSet {
  54   public:
  55     /** the number of blocks in this set */
  56     int ways;
  57
  58     /** Cache blocks in this set, maintained in LIFO order where
  59         0 = Last in (head) */
  60     SplitBlk *lastIn;
  61     SplitBlk *firstIn;
  62
  63     /** has the initial "filling" of this set finished? i.e., have you had
  64      * 'ways' number of compulsory misses in this set yet? if withValue == ways,
  65      * then yes.  withValue is meant to be the number of blocks in the set that have
  66      * gone through their first compulsory miss.
  67      */
  68     int withValue;
  69
  70     /**
  71      * Find a block matching the tag in this set.
  72      * @param asid The address space ID.
  73      * @param tag the Tag you are looking for
  74      * @return Pointer to the block, if found, NULL otherwise
  75      */
  76     SplitBlk* findBlk(Addr tag) const;
  77
  78     void moveToLastIn(SplitBlk *blk);
  79     void moveToFirstIn(SplitBlk *blk);
  80
  81     LIFOSet()
  82         : ways(-1), lastIn(NULL), firstIn(NULL), withValue(0)
  83     {}
  84 };
  85
  86 /**
  87  * A LIFO cache tag store.
  88  */
  89 class SplitLIFO : public BaseTags
  90 {
  91   public:
  92     /** Typedef the block type used in this tag store. */
  93     typedef SplitBlk BlkType;
  94     /** Typedef for a list of pointers to the local block class. */
  95     typedef std::list<SplitBlk*> BlkList;
  96   protected:
  97     /** The number of bytes in a block. */
  98     const int blkSize;
  99     /** the size of the cache in bytes */
 100     const int size;
 101     /** the number of blocks in the cache */
 102     const int numBlks;
 103     /** the number of sets in the cache */
 104     const int numSets;
 105     /** the number of ways in the cache */
 106     const int ways;
 107     /** The hit latency. */
 108     const int hitLatency;
 109     /** whether this is a "2 queue" replacement @sa moveToLastIn @sa moveToFirstIn */
 110     const bool twoQueue;
 111     /** indicator for which partition this is */
 112     const int part;
 113
 114     /** The cache blocks. */
 115     SplitBlk *blks;
 116     /** The Cache sets */
 117     LIFOSet *sets;
 118     /** The data blocks, 1 per cache block. */
 119     uint8_t *dataBlks;
 120
 121     /** The amount to shift the address to get the set. */
 122     int setShift;
 123     /** The amount to shift the address to get the tag. */
 124     int tagShift;
 125     /** Mask out all bits that aren't part of the set index. */
 126     unsigned setMask;
 127     /** Mask out all bits that aren't part of the block offset. */
 128     unsigned blkMask;
 129
 130
 131     /** the number of hit in this partition */
 132     Stats::Scalar<> hits;
 133     /** the number of blocks brought into this partition (i.e. misses) */
 134     Stats::Scalar<> misses;
 135     /** the number of invalidations in this partition */
 136     Stats::Scalar<> invalidations;
 137
 138 public:
 139     /**
 140      * Construct and initialize this tag store.
 141      * @param _numSets The number of sets in the cache.
 142      * @param _blkSize The number of bytes in a block.
 143      * @param _assoc The associativity of the cache.
 144      * @param _hit_latency The latency in cycles for a hit.
 145      */
 146     SplitLIFO(int _blkSize, int _size, int _ways, int _hit_latency, bool twoQueue, int _part);
 147
 148     /**
 149      * Destructor
 150      */
 151     virtual ~SplitLIFO();
 152
 153     /**
 154      * Register the statistics for this object
 155      * @param name The name to precede the stat
 156      */
 157     void regStats(const std::string &name);
 158
 159     /**
 160      * Return the block size.
 161      * @return the block size.
 162      */
 163     int getBlockSize()
 164     {
 165         return blkSize;
 166     }
 167
 168     /**
 169      * Return the subblock size. In the case of LIFO it is always the block
 170      * size.
 171      * @return The block size.
 172      */
 173     int getSubBlockSize()
 174     {
 175         return blkSize;
 176     }
 177
 178     /**
 179      * Search for the address in the cache.
 180      * @param asid The address space ID.
 181      * @param addr The address to find.
 182      * @return True if the address is in the cache.
 183      */
 184     bool probe( Addr addr) const;
 185
 186     /**
 187      * Invalidate the given block.
 188      * @param blk The block to invalidate.
 189      */
 190     void invalidateBlk(BlkType *blk);
 191
 192     /**
 193      * Finds the given address in the cache and update replacement data.
 194      * Returns the access latency as a side effect.
 195      * @param addr The address to find.
 196      * @param asid The address space ID.
 197      * @param lat The access latency.
 198      * @return Pointer to the cache block if found.
 199      */
 200     SplitBlk* findBlock(Addr addr, int &lat);
 201
 202     /**
 203      * Finds the given address in the cache, do not update replacement data.
 204      * @param addr The address to find.
 205      * @param asid The address space ID.
 206      * @return Pointer to the cache block if found.
 207      */
 208     SplitBlk* findBlock(Addr addr) const;
 209
 210     /**
 211      * Find a replacement block for the address provided.
 212      * @param pkt The request to a find a replacement candidate for.
 213      * @param writebacks List for any writebacks to be performed.
 214      * @param compress_blocks List of blocks to compress, for adaptive comp.
 215      * @return The block to place the replacement in.
 216      */
 217     SplitBlk* findReplacement(PacketPtr &pkt, PacketList &writebacks,
 218                             BlkList &compress_blocks);
 219
 220     /**
 221      * Generate the tag from the given address.
 222      * @param addr The address to get the tag from.
 223      * @return The tag of the address.
 224      */
 225     Addr extractTag(Addr addr) const
 226     {
 227         return (addr >> tagShift);
 228     }
 229
 230      /**
 231      * Generate the tag from the given address.
 232      * @param addr The address to get the tag from.
 233      * @param blk Ignored
 234      * @return The tag of the address.
 235      */
 236     Addr extractTag(Addr addr, SplitBlk *blk) const
 237     {
 238         return (addr >> tagShift);
 239     }
 240
 241    /**
 242      * Calculate the set index from the address.
 243      * @param addr The address to get the set from.
 244      * @return The set index of the address.
 245      */
 246     int extractSet(Addr addr) const
 247     {
 248         return ((addr >> setShift) & setMask);
 249     }
 250
 251     /**
 252      * Get the block offset from an address.
 253      * @param addr The address to get the offset of.
 254      * @return The block offset.
 255      */
 256     int extractBlkOffset(Addr addr) const
 257     {
 258         return (addr & blkMask);
 259     }
 260
 261     /**
 262      * Align an address to the block size.
 263      * @param addr the address to align.
 264      * @return The block address.
 265      */
 266     Addr blkAlign(Addr addr) const
 267     {
 268         return (addr & ~(Addr)blkMask);
 269     }
 270
 271     /**
 272      * Regenerate the block address from the tag.
 273      * @param tag The tag of the block.
 274      * @param set The set of the block.
 275      * @return The block address.
 276      */
 277     Addr regenerateBlkAddr(Addr tag, unsigned set) const
 278     {
 279         return ((tag << tagShift) | ((Addr)set << setShift));
 280     }
 281
 282     /**
 283      * Return the hit latency.
 284      * @return the hit latency.
 285      */
 286     int getHitLatency() const
 287     {
 288         return hitLatency;
 289     }
 290
 291     /**
 292      * Read the data out of the internal storage of the given cache block.
 293      * @param blk The cache block to read.
 294      * @param data The buffer to read the data into.
 295      * @return The cache block's data.
 296      */
 297     void readData(SplitBlk *blk, uint8_t *data)
 298     {
 299         memcpy(data, blk->data, blk->size);
 300     }
 301
 302     /**
 303      * Write data into the internal storage of the given cache block. Since in
 304      * LIFO does not store data differently this just needs to update the size.
 305      * @param blk The cache block to write.
 306      * @param data The data to write.
 307      * @param size The number of bytes to write.
 308      * @param writebacks A list for any writebacks to be performed. May be
 309      * needed when writing to a compressed block.
 310      */
 311     void writeData(SplitBlk *blk, uint8_t *data, int size,
 312                    PacketList & writebacks)
 313     {
 314         assert(size <= blkSize);
 315         blk->size = size;
 316     }
 317
 318     /**
 319      * Called at end of simulation to complete average block reference stats.
 320      */
 321     virtual void cleanupRefs();
 322 };
 323
 324 #endif