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40 * Authors: Erik Hallnor
45 * Declaration of a fully associative LRU tag store.
48 #ifndef __MEM_CACHE_TAGS_FA_LRU_HH__
49 #define __MEM_CACHE_TAGS_FA_LRU_HH__
53 #include "base/hashmap.hh"
54 #include "mem/cache/tags/base.hh"
55 #include "mem/cache/blk.hh"
56 #include "mem/packet.hh"
59 * A fully associative cache block.
61 class FALRUBlk : public CacheBlk
64 /** The previous block in LRU order. */
66 /** The next block in LRU order. */
68 /** Has this block been touched? */
72 * A bit mask of the sizes of cache that this block is resident in.
73 * Each bit represents a power of 2 in MB size cache.
74 * If bit 0 is set, this block is in a 1MB cache
75 * If bit 2 is set, this block is in a 4MB cache, etc.
76 * There is one bit for each cache smaller than the full size (default
83 * A fully associative LRU cache. Keeps statistics for accesses to a number of
84 * cache sizes at once.
86 class FALRU : public BaseTags
89 /** Typedef the block type used in this class. */
90 typedef FALRUBlk BlkType;
91 /** Typedef a list of pointers to the local block type. */
92 typedef std::list<FALRUBlk*> BlkList;
95 /** The block size of the cache. */
96 const unsigned blkSize;
97 /** The size of the cache. */
99 /** The hit latency of the cache. */
100 const Cycles hitLatency;
102 /** Array of pointers to blocks at the cache size boundaries. */
103 FALRUBlk **cacheBoundaries;
104 /** A mask for the FALRUBlk::inCache bits. */
106 /** The number of different size caches being tracked. */
109 /** The cache blocks. */
112 /** The MRU block. */
114 /** The LRU block. */
117 /** Hash table type mapping addresses to cache block pointers. */
118 typedef m5::hash_map<Addr, FALRUBlk *, m5::hash<Addr> > hash_t;
119 /** Iterator into the address hash table. */
120 typedef hash_t::const_iterator tagIterator;
122 /** The address hash table. */
126 * Find the cache block for the given address.
127 * @param addr The address to find.
128 * @return The cache block of the address, if any.
130 FALRUBlk * hashLookup(Addr addr) const;
133 * Move a cache block to the MRU position.
134 * @param blk The block to promote.
136 void moveToHead(FALRUBlk *blk);
139 * Check to make sure all the cache boundaries are still where they should
140 * be. Used for debugging.
141 * @return True if everything is correct.
146 * @defgroup FALRUStats Fully Associative LRU specific statistics
147 * The FA lru stack lets us track multiple cache sizes at once. These
148 * statistics track the hits and misses for different cache sizes.
152 /** Hits in each cache size >= 128K. */
154 /** Misses in each cache size >= 128K. */
155 Stats::Vector misses;
156 /** Total number of accesses. */
157 Stats::Scalar accesses;
165 * Construct and initialize this cache tagstore.
166 * @param blkSize The block size of the cache.
167 * @param size The size of the cache.
168 * @param hit_latency The hit latency of the cache.
170 FALRU(unsigned blkSize, unsigned size, Cycles hit_latency);
174 * Register the stats for this object.
175 * @param name The name to prepend to the stats name.
177 void regStats(const std::string &name);
180 * Invalidate a cache block.
181 * @param blk The block to invalidate.
183 void invalidate(BlkType *blk);
186 * Access block and update replacement data. May not succeed, in which case
187 * NULL pointer is returned. This has all the implications of a cache
188 * access and should only be used as such.
189 * Returns the access latency and inCache flags as a side effect.
190 * @param addr The address to look for.
191 * @param asid The address space ID.
192 * @param lat The latency of the access.
193 * @param inCache The FALRUBlk::inCache flags.
194 * @return Pointer to the cache block.
196 FALRUBlk* accessBlock(Addr addr, Cycles &lat, int context_src, int *inCache = 0);
199 * Find the block in the cache, do not update the replacement data.
200 * @param addr The address to look for.
201 * @param asid The address space ID.
202 * @return Pointer to the cache block.
204 FALRUBlk* findBlock(Addr addr) const;
207 * Find a replacement block for the address provided.
208 * @param pkt The request to a find a replacement candidate for.
209 * @param writebacks List for any writebacks to be performed.
210 * @return The block to place the replacement in.
212 FALRUBlk* findVictim(Addr addr, PacketList & writebacks);
214 void insertBlock(Addr addr, BlkType *blk, int context_src);
217 * Return the hit latency of this cache.
218 * @return The hit latency.
220 Cycles getHitLatency() const
226 * Return the block size of this cache.
227 * @return The block size.
236 * Return the subblock size of this cache, always the block size.
237 * @return The block size.
240 getSubBlockSize() const
246 * Align an address to the block size.
247 * @param addr the address to align.
248 * @return The aligned address.
250 Addr blkAlign(Addr addr) const
252 return (addr & ~(Addr)(blkSize-1));
256 * Generate the tag from the addres. For fully associative this is just the
258 * @param addr The address to get the tag from.
261 Addr extractTag(Addr addr) const
263 return blkAlign(addr);
267 * Return the set of an address. Only one set in a fully associative cache.
268 * @param addr The address to get the set from.
271 int extractSet(Addr addr) const
277 * Calculate the block offset of an address.
278 * @param addr the address to get the offset of.
279 * @return the block offset.
281 int extractBlkOffset(Addr addr) const
283 return (addr & (Addr)(blkSize-1));
287 * Regenerate the block address from the tag and the set.
288 * @param tag The tag of the block.
289 * @param set The set the block belongs to.
290 * @return the block address.
292 Addr regenerateBlkAddr(Addr tag, int set) const
298 *iterated through all blocks and clear all locks
299 *Needed to clear all lock tracking at once
301 virtual void clearLocks();
304 * @todo Implement as in lru. Currently not used
306 virtual std::string print() const { return ""; }
309 * Visit each block in the tag store and apply a visitor to the
312 * The visitor should be a function (or object that behaves like a
313 * function) that takes a cache block reference as its parameter
314 * and returns a bool. A visitor can request the traversal to be
315 * stopped by returning false, returning true causes it to be
316 * called for the next block in the tag store.
318 * \param visitor Visitor to call on each block.
320 template <typename V>
321 void forEachBlk(V &visitor) {
322 for (int i = 0; i < numBlocks; i++) {
323 if (!visitor(blks[i]))
329 #endif // __MEM_CACHE_TAGS_FA_LRU_HH__