cache.hh revision 4190:5069dfa3d62e
1/* 2 * Copyright (c) 2002-2005 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: Erik Hallnor 29 * Dave Greene 30 * Steve Reinhardt 31 */ 32 33/** 34 * @file 35 * Describes a cache based on template policies. 36 */ 37 38#ifndef __CACHE_HH__ 39#define __CACHE_HH__ 40 41#include "base/compression/base.hh" 42#include "base/misc.hh" // fatal, panic, and warn 43#include "cpu/smt.hh" // SMT_MAX_THREADS 44 45#include "mem/cache/base_cache.hh" 46#include "mem/cache/cache_blk.hh" 47#include "mem/cache/miss/miss_buffer.hh" 48 49//Forward decleration 50class MSHR; 51class BasePrefetcher; 52 53/** 54 * A template-policy based cache. The behavior of the cache can be altered by 55 * supplying different template policies. TagStore handles all tag and data 56 * storage @sa TagStore. Buffering handles all misses and writes/writebacks 57 * @sa MissQueue. Coherence handles all coherence policy details @sa 58 * UniCoherence, SimpleMultiCoherence. 59 */ 60template <class TagStore, class Coherence> 61class Cache : public BaseCache 62{ 63 public: 64 /** Define the type of cache block to use. */ 65 typedef typename TagStore::BlkType BlkType; 66 /** A typedef for a list of BlkType pointers. */ 67 typedef typename TagStore::BlkList BlkList; 68 69 bool prefetchAccess; 70 71 protected: 72 73 class CpuSidePort : public CachePort 74 { 75 public: 76 CpuSidePort(const std::string &_name, 77 Cache<TagStore,Coherence> *_cache); 78 79 // BaseCache::CachePort just has a BaseCache *; this function 80 // lets us get back the type info we lost when we stored the 81 // cache pointer there. 82 Cache<TagStore,Coherence> *myCache() { 83 return static_cast<Cache<TagStore,Coherence> *>(cache); 84 } 85 86 virtual bool recvTiming(PacketPtr pkt); 87 88 virtual Tick recvAtomic(PacketPtr pkt); 89 90 virtual void recvFunctional(PacketPtr pkt); 91 }; 92 93 class MemSidePort : public CachePort 94 { 95 public: 96 MemSidePort(const std::string &_name, 97 Cache<TagStore,Coherence> *_cache); 98 99 // BaseCache::CachePort just has a BaseCache *; this function 100 // lets us get back the type info we lost when we stored the 101 // cache pointer there. 102 Cache<TagStore,Coherence> *myCache() { 103 return static_cast<Cache<TagStore,Coherence> *>(cache); 104 } 105 106 virtual bool recvTiming(PacketPtr pkt); 107 108 virtual Tick recvAtomic(PacketPtr pkt); 109 110 virtual void recvFunctional(PacketPtr pkt); 111 }; 112 113 /** Tag and data Storage */ 114 TagStore *tags; 115 /** Miss and Writeback handler */ 116 MissBuffer *missQueue; 117 /** Coherence protocol. */ 118 Coherence *coherence; 119 120 /** Prefetcher */ 121 BasePrefetcher *prefetcher; 122 123 /** 124 * The clock ratio of the outgoing bus. 125 * Used for calculating critical word first. 126 */ 127 int busRatio; 128 129 /** 130 * The bus width in bytes of the outgoing bus. 131 * Used for calculating critical word first. 132 */ 133 int busWidth; 134 135 /** 136 * The latency of a hit in this device. 137 */ 138 int hitLatency; 139 140 /** 141 * A permanent mem req to always be used to cause invalidations. 142 * Used to append to target list, to cause an invalidation. 143 */ 144 PacketPtr invalidatePkt; 145 Request *invalidateReq; 146 147 /** 148 * Policy class for performing compression. 149 */ 150 CompressionAlgorithm *compressionAlg; 151 152 /** 153 * The block size of this cache. Set to value in the Tags object. 154 */ 155 const int16_t blkSize; 156 157 /** 158 * Can this cache should allocate a block on a line-sized write miss. 159 */ 160 const bool doFastWrites; 161 162 const bool prefetchMiss; 163 164 /** 165 * Can the data can be stored in a compressed form. 166 */ 167 const bool storeCompressed; 168 169 /** 170 * Do we need to compress blocks on writebacks (i.e. because 171 * writeback bus is compressed but storage is not)? 172 */ 173 const bool compressOnWriteback; 174 175 /** 176 * The latency of a compression operation. 177 */ 178 const int16_t compLatency; 179 180 /** 181 * Should we use an adaptive compression scheme. 182 */ 183 const bool adaptiveCompression; 184 185 /** 186 * Do writebacks need to be compressed (i.e. because writeback bus 187 * is compressed), whether or not they're already compressed for 188 * storage. 189 */ 190 const bool writebackCompressed; 191 192 /** 193 * Compare the internal block data to the fast access block data. 194 * @param blk The cache block to check. 195 * @return True if the data is the same. 196 */ 197 bool verifyData(BlkType *blk); 198 199 /** 200 * Update the internal data of the block. The data to write is assumed to 201 * be in the fast access data. 202 * @param blk The block with the data to update. 203 * @param writebacks A list to store any generated writebacks. 204 * @param compress_block True if we should compress this block 205 */ 206 void updateData(BlkType *blk, PacketList &writebacks, bool compress_block); 207 208 /** 209 * Handle a replacement for the given request. 210 * @param blk A pointer to the block, usually NULL 211 * @param pkt The memory request to satisfy. 212 * @param new_state The new state of the block. 213 * @param writebacks A list to store any generated writebacks. 214 */ 215 BlkType* doReplacement(BlkType *blk, PacketPtr &pkt, 216 CacheBlk::State new_state, PacketList &writebacks); 217 218 /** 219 * Does all the processing necessary to perform the provided request. 220 * @param pkt The memory request to perform. 221 * @param lat The latency of the access. 222 * @param writebacks List for any writebacks that need to be performed. 223 * @param update True if the replacement data should be updated. 224 * @return Pointer to the cache block touched by the request. NULL if it 225 * was a miss. 226 */ 227 BlkType* handleAccess(PacketPtr &pkt, int & lat, 228 PacketList & writebacks, bool update = true); 229 230 /** 231 * Populates a cache block and handles all outstanding requests for the 232 * satisfied fill request. This version takes an MSHR pointer and uses its 233 * request to fill the cache block, while repsonding to its targets. 234 * @param blk The cache block if it already exists. 235 * @param mshr The MSHR that contains the fill data and targets to satisfy. 236 * @param new_state The state of the new cache block. 237 * @param writebacks List for any writebacks that need to be performed. 238 * @return Pointer to the new cache block. 239 */ 240 BlkType* handleFill(BlkType *blk, MSHR * mshr, CacheBlk::State new_state, 241 PacketList & writebacks, PacketPtr pkt); 242 243 /** 244 * Populates a cache block and handles all outstanding requests for the 245 * satisfied fill request. This version takes two memory requests. One 246 * contains the fill data, the other is an optional target to satisfy. 247 * Used for Cache::probe. 248 * @param blk The cache block if it already exists. 249 * @param pkt The memory request with the fill data. 250 * @param new_state The state of the new cache block. 251 * @param writebacks List for any writebacks that need to be performed. 252 * @param target The memory request to perform after the fill. 253 * @return Pointer to the new cache block. 254 */ 255 BlkType* handleFill(BlkType *blk, PacketPtr &pkt, 256 CacheBlk::State new_state, 257 PacketList & writebacks, PacketPtr target = NULL); 258 259 /** 260 * Sets the blk to the new state and handles the given request. 261 * @param blk The cache block being snooped. 262 * @param new_state The new coherence state for the block. 263 * @param pkt The request to satisfy 264 */ 265 void handleSnoop(BlkType *blk, CacheBlk::State new_state, 266 PacketPtr &pkt); 267 268 /** 269 * Sets the blk to the new state. 270 * @param blk The cache block being snooped. 271 * @param new_state The new coherence state for the block. 272 */ 273 void handleSnoop(BlkType *blk, CacheBlk::State new_state); 274 275 /** 276 * Create a writeback request for the given block. 277 * @param blk The block to writeback. 278 * @return The writeback request for the block. 279 */ 280 PacketPtr writebackBlk(BlkType *blk); 281 282 public: 283 284 class Params 285 { 286 public: 287 TagStore *tags; 288 MissBuffer *missQueue; 289 Coherence *coherence; 290 BaseCache::Params baseParams; 291 BasePrefetcher*prefetcher; 292 bool prefetchAccess; 293 int hitLatency; 294 CompressionAlgorithm *compressionAlg; 295 const int16_t blkSize; 296 const bool doFastWrites; 297 const bool prefetchMiss; 298 const bool storeCompressed; 299 const bool compressOnWriteback; 300 const int16_t compLatency; 301 const bool adaptiveCompression; 302 const bool writebackCompressed; 303 304 Params(TagStore *_tags, MissBuffer *mq, Coherence *coh, 305 BaseCache::Params params, 306 BasePrefetcher *_prefetcher, 307 bool prefetch_access, int hit_latency, 308 bool do_fast_writes, 309 bool store_compressed, bool adaptive_compression, 310 bool writeback_compressed, 311 CompressionAlgorithm *_compressionAlg, int comp_latency, 312 bool prefetch_miss) 313 : tags(_tags), missQueue(mq), coherence(coh), 314 baseParams(params), 315 prefetcher(_prefetcher), prefetchAccess(prefetch_access), 316 hitLatency(hit_latency), 317 compressionAlg(_compressionAlg), 318 blkSize(_tags->getBlockSize()), 319 doFastWrites(do_fast_writes), 320 prefetchMiss(prefetch_miss), 321 storeCompressed(store_compressed), 322 compressOnWriteback(!store_compressed && writeback_compressed), 323 compLatency(comp_latency), 324 adaptiveCompression(adaptive_compression), 325 writebackCompressed(writeback_compressed) 326 { 327 } 328 }; 329 330 /** Instantiates a basic cache object. */ 331 Cache(const std::string &_name, Params ¶ms); 332 333 virtual Port *getPort(const std::string &if_name, int idx = -1); 334 virtual void deletePortRefs(Port *p); 335 336 virtual void recvStatusChange(Port::Status status, bool isCpuSide); 337 338 void regStats(); 339 340 /** 341 * Performs the access specified by the request. 342 * @param pkt The request to perform. 343 * @return The result of the access. 344 */ 345 bool access(PacketPtr &pkt); 346 347 /** 348 * Selects a request to send on the bus. 349 * @return The memory request to service. 350 */ 351 virtual PacketPtr getPacket(); 352 353 /** 354 * Was the request was sent successfully? 355 * @param pkt The request. 356 * @param success True if the request was sent successfully. 357 */ 358 virtual void sendResult(PacketPtr &pkt, MSHR* mshr, bool success); 359 360 /** 361 * Was the CSHR request was sent successfully? 362 * @param pkt The request. 363 * @param success True if the request was sent successfully. 364 */ 365 virtual void sendCoherenceResult(PacketPtr &pkt, MSHR* cshr, bool success); 366 367 /** 368 * Handles a response (cache line fill/write ack) from the bus. 369 * @param pkt The request being responded to. 370 */ 371 void handleResponse(PacketPtr &pkt); 372 373 /** 374 * Selects a coherence message to forward to lower levels of the hierarchy. 375 * @return The coherence message to forward. 376 */ 377 virtual PacketPtr getCoherencePacket(); 378 379 /** 380 * Snoops bus transactions to maintain coherence. 381 * @param pkt The current bus transaction. 382 */ 383 void snoop(PacketPtr &pkt); 384 385 void snoopResponse(PacketPtr &pkt); 386 387 /** 388 * Squash all requests associated with specified thread. 389 * intended for use by I-cache. 390 * @param threadNum The thread to squash. 391 */ 392 void squash(int threadNum) 393 { 394 missQueue->squash(threadNum); 395 } 396 397 /** 398 * Return the number of outstanding misses in a Cache. 399 * Default returns 0. 400 * 401 * @retval unsigned The number of missing still outstanding. 402 */ 403 unsigned outstandingMisses() const 404 { 405 return missQueue->getMisses(); 406 } 407 408 /** 409 * Perform the access specified in the request and return the estimated 410 * time of completion. This function can either update the hierarchy state 411 * or just perform the access wherever the data is found depending on the 412 * state of the update flag. 413 * @param pkt The memory request to satisfy 414 * @param update If true, update the hierarchy, otherwise just perform the 415 * request. 416 * @return The estimated completion time. 417 */ 418 Tick probe(PacketPtr &pkt, bool update, CachePort * otherSidePort); 419 420 /** 421 * Snoop for the provided request in the cache and return the estimated 422 * time of completion. 423 * @todo Can a snoop probe not change state? 424 * @param pkt The memory request to satisfy 425 * @param update If true, update the hierarchy, otherwise just perform the 426 * request. 427 * @return The estimated completion time. 428 */ 429 Tick snoopProbe(PacketPtr &pkt); 430 431 bool inCache(Addr addr) { 432 return (tags->findBlock(addr) != 0); 433 } 434 435 bool inMissQueue(Addr addr) { 436 return (missQueue->findMSHR(addr) != 0); 437 } 438}; 439 440#endif // __CACHE_HH__ 441