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