cache.hh revision 11276:3561d002d8c7
1/* 2 * Copyright (c) 2012-2015 ARM Limited 3 * All rights reserved. 4 * 5 * The license below extends only to copyright in the software and shall 6 * not be construed as granting a license to any other intellectual 7 * property including but not limited to intellectual property relating 8 * to a hardware implementation of the functionality of the software 9 * licensed hereunder. You may use the software subject to the license 10 * terms below provided that you ensure that this notice is replicated 11 * unmodified and in its entirety in all distributions of the software, 12 * modified or unmodified, in source code or in binary form. 13 * 14 * Copyright (c) 2002-2005 The Regents of The University of Michigan 15 * All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions are 19 * met: redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer; 21 * redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution; 24 * neither the name of the copyright holders nor the names of its 25 * contributors may be used to endorse or promote products derived from 26 * this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 * 40 * Authors: Erik Hallnor 41 * Dave Greene 42 * Steve Reinhardt 43 * Ron Dreslinski 44 * Andreas Hansson 45 */ 46 47/** 48 * @file 49 * Describes a cache based on template policies. 50 */ 51 52#ifndef __MEM_CACHE_CACHE_HH__ 53#define __MEM_CACHE_CACHE_HH__ 54 55#include "base/misc.hh" // fatal, panic, and warn 56#include "enums/Clusivity.hh" 57#include "mem/cache/base.hh" 58#include "mem/cache/blk.hh" 59#include "mem/cache/mshr.hh" 60#include "mem/cache/tags/base.hh" 61#include "params/Cache.hh" 62#include "sim/eventq.hh" 63 64//Forward decleration 65class BasePrefetcher; 66 67/** 68 * A template-policy based cache. The behavior of the cache can be altered by 69 * supplying different template policies. TagStore handles all tag and data 70 * storage @sa TagStore, \ref gem5MemorySystem "gem5 Memory System" 71 */ 72class Cache : public BaseCache 73{ 74 public: 75 76 /** A typedef for a list of CacheBlk pointers. */ 77 typedef std::list<CacheBlk*> BlkList; 78 79 protected: 80 81 /** 82 * The CPU-side port extends the base cache slave port with access 83 * functions for functional, atomic and timing requests. 84 */ 85 class CpuSidePort : public CacheSlavePort 86 { 87 private: 88 89 // a pointer to our specific cache implementation 90 Cache *cache; 91 92 protected: 93 94 virtual bool recvTimingSnoopResp(PacketPtr pkt); 95 96 virtual bool recvTimingReq(PacketPtr pkt); 97 98 virtual Tick recvAtomic(PacketPtr pkt); 99 100 virtual void recvFunctional(PacketPtr pkt); 101 102 virtual AddrRangeList getAddrRanges() const; 103 104 public: 105 106 CpuSidePort(const std::string &_name, Cache *_cache, 107 const std::string &_label); 108 109 }; 110 111 /** 112 * Override the default behaviour of sendDeferredPacket to enable 113 * the memory-side cache port to also send requests based on the 114 * current MSHR status. This queue has a pointer to our specific 115 * cache implementation and is used by the MemSidePort. 116 */ 117 class CacheReqPacketQueue : public ReqPacketQueue 118 { 119 120 protected: 121 122 Cache &cache; 123 SnoopRespPacketQueue &snoopRespQueue; 124 125 public: 126 127 CacheReqPacketQueue(Cache &cache, MasterPort &port, 128 SnoopRespPacketQueue &snoop_resp_queue, 129 const std::string &label) : 130 ReqPacketQueue(cache, port, label), cache(cache), 131 snoopRespQueue(snoop_resp_queue) { } 132 133 /** 134 * Override the normal sendDeferredPacket and do not only 135 * consider the transmit list (used for responses), but also 136 * requests. 137 */ 138 virtual void sendDeferredPacket(); 139 140 }; 141 142 /** 143 * The memory-side port extends the base cache master port with 144 * access functions for functional, atomic and timing snoops. 145 */ 146 class MemSidePort : public CacheMasterPort 147 { 148 private: 149 150 /** The cache-specific queue. */ 151 CacheReqPacketQueue _reqQueue; 152 153 SnoopRespPacketQueue _snoopRespQueue; 154 155 // a pointer to our specific cache implementation 156 Cache *cache; 157 158 protected: 159 160 virtual void recvTimingSnoopReq(PacketPtr pkt); 161 162 virtual bool recvTimingResp(PacketPtr pkt); 163 164 virtual Tick recvAtomicSnoop(PacketPtr pkt); 165 166 virtual void recvFunctionalSnoop(PacketPtr pkt); 167 168 public: 169 170 MemSidePort(const std::string &_name, Cache *_cache, 171 const std::string &_label); 172 }; 173 174 /** Tag and data Storage */ 175 BaseTags *tags; 176 177 /** Prefetcher */ 178 BasePrefetcher *prefetcher; 179 180 /** Temporary cache block for occasional transitory use */ 181 CacheBlk *tempBlock; 182 183 /** 184 * This cache should allocate a block on a line-sized write miss. 185 */ 186 const bool doFastWrites; 187 188 /** 189 * Turn line-sized writes into WriteInvalidate transactions. 190 */ 191 void promoteWholeLineWrites(PacketPtr pkt); 192 193 /** 194 * Notify the prefetcher on every access, not just misses. 195 */ 196 const bool prefetchOnAccess; 197 198 /** 199 * Clusivity with respect to the upstream cache, determining if we 200 * fill into both this cache and the cache above on a miss. Note 201 * that we currently do not support strict clusivity policies. 202 */ 203 const Enums::Clusivity clusivity; 204 205 /** 206 * Determine if clean lines should be written back or not. In 207 * cases where a downstream cache is mostly inclusive we likely 208 * want it to act as a victim cache also for lines that have not 209 * been modified. Hence, we cannot simply drop the line (or send a 210 * clean evict), but rather need to send the actual data. 211 */ 212 const bool writebackClean; 213 214 /** 215 * Upstream caches need this packet until true is returned, so 216 * hold it for deletion until a subsequent call 217 */ 218 std::unique_ptr<Packet> pendingDelete; 219 220 /** 221 * Writebacks from the tempBlock, resulting on the response path 222 * in atomic mode, must happen after the call to recvAtomic has 223 * finished (for the right ordering of the packets). We therefore 224 * need to hold on to the packets, and have a method and an event 225 * to send them. 226 */ 227 PacketPtr tempBlockWriteback; 228 229 /** 230 * Send the outstanding tempBlock writeback. To be called after 231 * recvAtomic finishes in cases where the block we filled is in 232 * fact the tempBlock, and now needs to be written back. 233 */ 234 void writebackTempBlockAtomic() { 235 assert(tempBlockWriteback != nullptr); 236 PacketList writebacks{tempBlockWriteback}; 237 doWritebacksAtomic(writebacks); 238 tempBlockWriteback = nullptr; 239 } 240 241 /** 242 * An event to writeback the tempBlock after recvAtomic 243 * finishes. To avoid other calls to recvAtomic getting in 244 * between, we create this event with a higher priority. 245 */ 246 EventWrapper<Cache, &Cache::writebackTempBlockAtomic> \ 247 writebackTempBlockAtomicEvent; 248 249 /** 250 * Store the outstanding requests that we are expecting snoop 251 * responses from so we can determine which snoop responses we 252 * generated and which ones were merely forwarded. 253 */ 254 std::unordered_set<RequestPtr> outstandingSnoop; 255 256 /** 257 * Does all the processing necessary to perform the provided request. 258 * @param pkt The memory request to perform. 259 * @param blk The cache block to be updated. 260 * @param lat The latency of the access. 261 * @param writebacks List for any writebacks that need to be performed. 262 * @return Boolean indicating whether the request was satisfied. 263 */ 264 bool access(PacketPtr pkt, CacheBlk *&blk, 265 Cycles &lat, PacketList &writebacks); 266 267 /** 268 *Handle doing the Compare and Swap function for SPARC. 269 */ 270 void cmpAndSwap(CacheBlk *blk, PacketPtr pkt); 271 272 /** 273 * Find a block frame for new block at address addr targeting the 274 * given security space, assuming that the block is not currently 275 * in the cache. Append writebacks if any to provided packet 276 * list. Return free block frame. May return NULL if there are 277 * no replaceable blocks at the moment. 278 */ 279 CacheBlk *allocateBlock(Addr addr, bool is_secure, PacketList &writebacks); 280 281 /** 282 * Invalidate a cache block. 283 * 284 * @param blk Block to invalidate 285 */ 286 void invalidateBlock(CacheBlk *blk); 287 288 /** 289 * Populates a cache block and handles all outstanding requests for the 290 * satisfied fill request. This version takes two memory requests. One 291 * contains the fill data, the other is an optional target to satisfy. 292 * @param pkt The memory request with the fill data. 293 * @param blk The cache block if it already exists. 294 * @param writebacks List for any writebacks that need to be performed. 295 * @param allocate Whether to allocate a block or use the temp block 296 * @return Pointer to the new cache block. 297 */ 298 CacheBlk *handleFill(PacketPtr pkt, CacheBlk *blk, 299 PacketList &writebacks, bool allocate); 300 301 /** 302 * Determine whether we should allocate on a fill or not. If this 303 * cache is mostly inclusive with regards to the upstream cache(s) 304 * we always allocate (for any non-forwarded and cacheable 305 * requests). In the case of a mostly exclusive cache, we allocate 306 * on fill if the packet did not come from a cache, thus if we: 307 * are dealing with a whole-line write (the latter behaves much 308 * like a writeback), the original target packet came from a 309 * non-caching source, or if we are performing a prefetch or LLSC. 310 * 311 * @param cmd Command of the incoming requesting packet 312 * @return Whether we should allocate on the fill 313 */ 314 inline bool allocOnFill(MemCmd cmd) const override 315 { 316 return clusivity == Enums::mostly_incl || 317 cmd == MemCmd::WriteLineReq || 318 cmd == MemCmd::ReadReq || 319 cmd == MemCmd::WriteReq || 320 cmd.isPrefetch() || 321 cmd.isLLSC(); 322 } 323 324 /** 325 * Performs the access specified by the request. 326 * @param pkt The request to perform. 327 * @return The result of the access. 328 */ 329 bool recvTimingReq(PacketPtr pkt); 330 331 /** 332 * Insert writebacks into the write buffer 333 */ 334 void doWritebacks(PacketList& writebacks, Tick forward_time); 335 336 /** 337 * Send writebacks down the memory hierarchy in atomic mode 338 */ 339 void doWritebacksAtomic(PacketList& writebacks); 340 341 /** 342 * Handles a response (cache line fill/write ack) from the bus. 343 * @param pkt The response packet 344 */ 345 void recvTimingResp(PacketPtr pkt); 346 347 /** 348 * Snoops bus transactions to maintain coherence. 349 * @param pkt The current bus transaction. 350 */ 351 void recvTimingSnoopReq(PacketPtr pkt); 352 353 /** 354 * Handle a snoop response. 355 * @param pkt Snoop response packet 356 */ 357 void recvTimingSnoopResp(PacketPtr pkt); 358 359 /** 360 * Performs the access specified by the request. 361 * @param pkt The request to perform. 362 * @return The number of ticks required for the access. 363 */ 364 Tick recvAtomic(PacketPtr pkt); 365 366 /** 367 * Snoop for the provided request in the cache and return the estimated 368 * time taken. 369 * @param pkt The memory request to snoop 370 * @return The number of ticks required for the snoop. 371 */ 372 Tick recvAtomicSnoop(PacketPtr pkt); 373 374 /** 375 * Performs the access specified by the request. 376 * @param pkt The request to perform. 377 * @param fromCpuSide from the CPU side port or the memory side port 378 */ 379 void functionalAccess(PacketPtr pkt, bool fromCpuSide); 380 381 void satisfyCpuSideRequest(PacketPtr pkt, CacheBlk *blk, 382 bool deferred_response = false, 383 bool pending_downgrade = false); 384 bool satisfyMSHR(MSHR *mshr, PacketPtr pkt, CacheBlk *blk); 385 386 void doTimingSupplyResponse(PacketPtr req_pkt, const uint8_t *blk_data, 387 bool already_copied, bool pending_inval); 388 389 /** 390 * Perform an upward snoop if needed, and update the block state 391 * (possibly invalidating the block). Also create a response if required. 392 * 393 * @param pkt Snoop packet 394 * @param blk Cache block being snooped 395 * @param is_timing Timing or atomic for the response 396 * @param is_deferred Is this a deferred snoop or not? 397 * @param pending_inval Do we have a pending invalidation? 398 * 399 * @return The snoop delay incurred by the upwards snoop 400 */ 401 uint32_t handleSnoop(PacketPtr pkt, CacheBlk *blk, 402 bool is_timing, bool is_deferred, bool pending_inval); 403 404 /** 405 * Create a writeback request for the given block. 406 * @param blk The block to writeback. 407 * @return The writeback request for the block. 408 */ 409 PacketPtr writebackBlk(CacheBlk *blk); 410 411 /** 412 * Create a CleanEvict request for the given block. 413 * @param blk The block to evict. 414 * @return The CleanEvict request for the block. 415 */ 416 PacketPtr cleanEvictBlk(CacheBlk *blk); 417 418 419 void memWriteback() override; 420 void memInvalidate() override; 421 bool isDirty() const override; 422 423 /** 424 * Cache block visitor that writes back dirty cache blocks using 425 * functional writes. 426 * 427 * \return Always returns true. 428 */ 429 bool writebackVisitor(CacheBlk &blk); 430 /** 431 * Cache block visitor that invalidates all blocks in the cache. 432 * 433 * @warn Dirty cache lines will not be written back to memory. 434 * 435 * \return Always returns true. 436 */ 437 bool invalidateVisitor(CacheBlk &blk); 438 439 /** 440 * Generate an appropriate downstream bus request packet for the 441 * given parameters. 442 * @param cpu_pkt The upstream request that needs to be satisfied. 443 * @param blk The block currently in the cache corresponding to 444 * cpu_pkt (NULL if none). 445 * @param needsExclusive Indicates that an exclusive copy is required 446 * even if the request in cpu_pkt doesn't indicate that. 447 * @return A new Packet containing the request, or NULL if the 448 * current request in cpu_pkt should just be forwarded on. 449 */ 450 PacketPtr getBusPacket(PacketPtr cpu_pkt, CacheBlk *blk, 451 bool needsExclusive) const; 452 453 /** 454 * Return the next MSHR to service, either a pending miss from the 455 * mshrQueue, a buffered write from the write buffer, or something 456 * from the prefetcher. This function is responsible for 457 * prioritizing among those sources on the fly. 458 */ 459 MSHR *getNextMSHR(); 460 461 /** 462 * Send up a snoop request and find cached copies. If cached copies are 463 * found, set the BLOCK_CACHED flag in pkt. 464 */ 465 bool isCachedAbove(PacketPtr pkt, bool is_timing = true) const; 466 467 /** 468 * Selects an outstanding request to service. Called when the 469 * cache gets granted the downstream bus in timing mode. 470 * @return The request to service, NULL if none found. 471 */ 472 PacketPtr getTimingPacket(); 473 474 /** 475 * Marks a request as in service (sent on the bus). This can have 476 * side effect since storage for no response commands is 477 * deallocated once they are successfully sent. Also remember if 478 * we are expecting a dirty response from another cache, 479 * effectively making this MSHR the ordering point. 480 */ 481 void markInService(MSHR *mshr, bool pending_dirty_resp); 482 483 /** 484 * Return whether there are any outstanding misses. 485 */ 486 bool outstandingMisses() const 487 { 488 return mshrQueue.allocated != 0; 489 } 490 491 CacheBlk *findBlock(Addr addr, bool is_secure) const { 492 return tags->findBlock(addr, is_secure); 493 } 494 495 bool inCache(Addr addr, bool is_secure) const override { 496 return (tags->findBlock(addr, is_secure) != 0); 497 } 498 499 bool inMissQueue(Addr addr, bool is_secure) const override { 500 return (mshrQueue.findMatch(addr, is_secure) != 0); 501 } 502 503 /** 504 * Find next request ready time from among possible sources. 505 */ 506 Tick nextMSHRReadyTime() const; 507 508 public: 509 /** Instantiates a basic cache object. */ 510 Cache(const CacheParams *p); 511 512 /** Non-default destructor is needed to deallocate memory. */ 513 virtual ~Cache(); 514 515 void regStats() override; 516 517 /** serialize the state of the caches 518 * We currently don't support checkpointing cache state, so this panics. 519 */ 520 void serialize(CheckpointOut &cp) const override; 521 void unserialize(CheckpointIn &cp) override; 522}; 523 524/** 525 * Wrap a method and present it as a cache block visitor. 526 * 527 * For example the forEachBlk method in the tag arrays expects a 528 * callable object/function as their parameter. This class wraps a 529 * method in an object and presents callable object that adheres to 530 * the cache block visitor protocol. 531 */ 532class CacheBlkVisitorWrapper : public CacheBlkVisitor 533{ 534 public: 535 typedef bool (Cache::*VisitorPtr)(CacheBlk &blk); 536 537 CacheBlkVisitorWrapper(Cache &_cache, VisitorPtr _visitor) 538 : cache(_cache), visitor(_visitor) {} 539 540 bool operator()(CacheBlk &blk) override { 541 return (cache.*visitor)(blk); 542 } 543 544 private: 545 Cache &cache; 546 VisitorPtr visitor; 547}; 548 549/** 550 * Cache block visitor that determines if there are dirty blocks in a 551 * cache. 552 * 553 * Use with the forEachBlk method in the tag array to determine if the 554 * array contains dirty blocks. 555 */ 556class CacheBlkIsDirtyVisitor : public CacheBlkVisitor 557{ 558 public: 559 CacheBlkIsDirtyVisitor() 560 : _isDirty(false) {} 561 562 bool operator()(CacheBlk &blk) override { 563 if (blk.isDirty()) { 564 _isDirty = true; 565 return false; 566 } else { 567 return true; 568 } 569 } 570 571 /** 572 * Does the array contain a dirty line? 573 * 574 * \return true if yes, false otherwise. 575 */ 576 bool isDirty() const { return _isDirty; }; 577 578 private: 579 bool _isDirty; 580}; 581 582#endif // __MEM_CACHE_CACHE_HH__ 583