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43 * Declaration of a common base class for cache tagstore objects.
46 #ifndef __MEM_CACHE_TAGS_BASE_HH__
47 #define __MEM_CACHE_TAGS_BASE_HH__
54 #include "base/callback.hh"
55 #include "base/logging.hh"
56 #include "base/statistics.hh"
57 #include "base/types.hh"
58 #include "mem/cache/cache_blk.hh"
59 #include "mem/packet.hh"
60 #include "params/BaseTags.hh"
61 #include "sim/clocked_object.hh"
65 class ReplaceableEntry;
68 * A common base class of Cache tagstore objects.
70 class BaseTags : public ClockedObject
73 /** The block size of the cache. */
74 const unsigned blkSize;
75 /** Mask out all bits that aren't part of the block offset. */
77 /** The size of the cache. */
79 /** The tag lookup latency of the cache. */
80 const Cycles lookupLatency;
82 /** System we are currently operating in. */
85 /** Indexing policy */
86 BaseIndexingPolicy *indexingPolicy;
89 * The number of tags that need to be touched to meet the warmup
92 const unsigned warmupBound;
93 /** Marked true when the cache is warmed up. */
96 /** the number of blocks in the cache */
97 const unsigned numBlocks;
99 /** The data blocks, 1 per cache block. */
100 std::unique_ptr<uint8_t[]> dataBlks;
103 * TODO: It would be good if these stats were acquired after warmup.
105 struct BaseTagStats : public Stats::Group
107 BaseTagStats(BaseTags &tags);
109 void regStats() override;
110 void preDumpStats() override;
114 /** Per tick average of the number of tags that hold valid data. */
115 Stats::Average tagsInUse;
117 /** The total number of references to a block before it is replaced. */
118 Stats::Scalar totalRefs;
121 * The number of reference counts sampled. This is different
122 * from replacements because we sample all the valid blocks
123 * when the simulator exits.
125 Stats::Scalar sampledRefs;
128 * Average number of references to a block before is was replaced.
129 * @todo This should change to an average stat once we have them.
131 Stats::Formula avgRefs;
133 /** The cycle that the warmup percentage was hit. 0 on failure. */
134 Stats::Scalar warmupCycle;
136 /** Average occupancy of each requestor using the cache */
137 Stats::AverageVector occupancies;
139 /** Average occ % of each requestor using the cache */
140 Stats::Formula avgOccs;
142 /** Occupancy of each context/cpu using the cache */
143 Stats::Vector occupanciesTaskId;
145 /** Occupancy of each context/cpu using the cache */
146 Stats::Vector2d ageTaskId;
148 /** Occ ratio of each context/cpu using the cache */
149 Stats::Formula ratioOccsTaskId;
151 /** Number of tags consulted over all accesses. */
152 Stats::Scalar tagAccesses;
153 /** Number of data blocks consulted over all accesses. */
154 Stats::Scalar dataAccesses;
158 typedef BaseTagsParams Params;
159 BaseTags(const Params &p);
164 virtual ~BaseTags() {}
167 * Initialize blocks. Must be overriden by every subclass that uses
168 * a block type different from its parent's, as the current Python
169 * code generation does not allow templates.
171 virtual void tagsInit() = 0;
174 * Average in the reference count for valid blocks when the simulation
180 * Computes stats just prior to dump event
185 * Print all tags used
190 * Finds the block in the cache without touching it.
192 * @param addr The address to look for.
193 * @param is_secure True if the target memory space is secure.
194 * @return Pointer to the cache block.
196 virtual CacheBlk *findBlock(Addr addr, bool is_secure) const;
199 * Find a block given set and way.
201 * @param set The set of the block.
202 * @param way The way of the block.
205 virtual ReplaceableEntry* findBlockBySetAndWay(int set, int way) const;
208 * Align an address to the block size.
209 * @param addr the address to align.
210 * @return The block address.
212 Addr blkAlign(Addr addr) const
214 return addr & ~blkMask;
218 * Calculate the block offset of an address.
219 * @param addr the address to get the offset of.
220 * @return the block offset.
222 int extractBlkOffset(Addr addr) const
224 return (addr & blkMask);
228 * Limit the allocation for the cache ways.
229 * @param ways The maximum number of ways available for replacement.
231 virtual void setWayAllocationMax(int ways)
233 panic("This tag class does not implement way allocation limit!\n");
237 * Get the way allocation mask limit.
238 * @return The maximum number of ways available for replacement.
240 virtual int getWayAllocationMax() const
242 panic("This tag class does not implement way allocation limit!\n");
247 * This function updates the tags when a block is invalidated
249 * @param blk A valid block to invalidate.
251 virtual void invalidate(CacheBlk *blk)
254 assert(blk->isValid());
256 stats.occupancies[blk->getSrcRequestorId()]--;
257 stats.totalRefs += blk->getRefCount();
264 * Find replacement victim based on address. If the address requires
265 * blocks to be evicted, their locations are listed for eviction. If a
266 * conventional cache is being used, the list only contains the victim.
267 * However, if using sector or compressed caches, the victim is one of
268 * the blocks to be evicted, but its location is the only one that will
269 * be assigned to the newly allocated block associated to this address.
272 * @param addr Address to find a victim for.
273 * @param is_secure True if the target memory space is secure.
274 * @param size Size, in bits, of new block to allocate.
275 * @param evict_blks Cache blocks to be evicted.
276 * @return Cache block to be replaced.
278 virtual CacheBlk* findVictim(Addr addr, const bool is_secure,
279 const std::size_t size,
280 std::vector<CacheBlk*>& evict_blks) = 0;
283 * Access block and update replacement data. May not succeed, in which case
284 * nullptr is returned. This has all the implications of a cache access and
285 * should only be used as such. Returns the tag lookup latency as a side
288 * @param addr The address to find.
289 * @param is_secure True if the target memory space is secure.
290 * @param lat The latency of the tag lookup.
291 * @return Pointer to the cache block if found.
293 virtual CacheBlk* accessBlock(Addr addr, bool is_secure, Cycles &lat) = 0;
296 * Generate the tag from the given address.
298 * @param addr The address to get the tag from.
299 * @return The tag of the address.
301 virtual Addr extractTag(const Addr addr) const;
304 * Insert the new block into the cache and update stats.
306 * @param pkt Packet holding the address to update
307 * @param blk The block to update.
309 virtual void insertBlock(const PacketPtr pkt, CacheBlk *blk);
312 * Move a block's metadata to another location decided by the replacement
313 * policy. It behaves as a swap, however, since the destination block
314 * should be invalid, the result is a move.
316 * @param src_blk The source block.
317 * @param dest_blk The destination block. Must be invalid.
319 virtual void moveBlock(CacheBlk *src_blk, CacheBlk *dest_blk);
322 * Regenerate the block address.
324 * @param block The block.
325 * @return the block address.
327 virtual Addr regenerateBlkAddr(const CacheBlk* blk) const = 0;
330 * Visit each block in the tags and apply a visitor
332 * The visitor should be a std::function that takes a cache block
333 * reference as its parameter.
335 * @param visitor Visitor to call on each block.
337 virtual void forEachBlk(std::function<void(CacheBlk &)> visitor) = 0;
340 * Find if any of the blocks satisfies a condition
342 * The visitor should be a std::function that takes a cache block
343 * reference as its parameter. The visitor will terminate the
344 * traversal early if the condition is satisfied.
346 * @param visitor Visitor to call on each block.
348 virtual bool anyBlk(std::function<bool(CacheBlk &)> visitor) = 0;
352 * Update the reference stats using data from the input block
354 * @param blk The input block
356 void cleanupRefsVisitor(CacheBlk &blk);
359 * Update the occupancy and age stats using data from the input block
361 * @param blk The input block
363 void computeStatsVisitor(CacheBlk &blk);
366 #endif //__MEM_CACHE_TAGS_BASE_HH__