1/* 2 * Copyright (c) 2018 Inria 3 * Copyright (c) 2013,2016-2018 ARM Limited 4 * All rights reserved. 5 * 6 * The license below extends only to copyright in the software and shall 7 * not be construed as granting a license to any other intellectual 8 * property including but not limited to intellectual property relating 9 * to a hardware implementation of the functionality of the software 10 * licensed hereunder. You may use the software subject to the license 11 * terms below provided that you ensure that this notice is replicated 12 * unmodified and in its entirety in all distributions of the software, 13 * modified or unmodified, in source code or in binary form. 14 * 15 * Copyright (c) 2003-2005 The Regents of The University of Michigan 16 * All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions are 20 * met: redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer; 22 * redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution; 25 * neither the name of the copyright holders nor the names of its 26 * contributors may be used to endorse or promote products derived from 27 * this software without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 40 * 41 * Authors: Erik Hallnor 42 * Nikos Nikoleris 43 * Daniel Carvalho 44 */ 45 46/** 47 * @file 48 * Definitions a fully associative LRU tagstore. 49 */ 50 51#include "mem/cache/tags/fa_lru.hh" 52 53#include <cassert> 54#include <sstream> 55 56#include "base/intmath.hh" 57#include "base/logging.hh" 58#include "mem/cache/base.hh" 59#include "mem/cache/replacement_policies/replaceable_entry.hh" 60 61std::string 62FALRUBlk::print() const 63{ 64 return csprintf("%s inCachesMask: %#x", CacheBlk::print(), inCachesMask); 65} 66 67FALRU::FALRU(const Params *p) 68 : BaseTags(p), 69 70 cacheTracking(p->min_tracked_cache_size, size, blkSize) 71{ 72 if (!isPowerOf2(blkSize)) 73 fatal("cache block size (in bytes) `%d' must be a power of two", 74 blkSize); 75 if (!isPowerOf2(size)) 76 fatal("Cache Size must be power of 2 for now"); 77 78 blks = new FALRUBlk[numBlocks]; 79} 80 81FALRU::~FALRU() 82{ 83 delete[] blks; 84} 85 86void 87FALRU::init(BaseCache* cache) 88{ 89 // Set parent cache 90 setCache(cache); 91 92 head = &(blks[0]); 93 head->prev = nullptr; 94 head->next = &(blks[1]); 95 head->setPosition(0, 0); 96 head->data = &dataBlks[0]; 97 98 for (unsigned i = 1; i < numBlocks - 1; i++) { 99 blks[i].prev = &(blks[i-1]); 100 blks[i].next = &(blks[i+1]); 101 blks[i].setPosition(0, i); 102 103 // Associate a data chunk to the block 104 blks[i].data = &dataBlks[blkSize*i]; 105 } 106 107 tail = &(blks[numBlocks - 1]); 108 tail->prev = &(blks[numBlocks - 2]); 109 tail->next = nullptr; 110 tail->setPosition(0, numBlocks - 1); 111 tail->data = &dataBlks[(numBlocks - 1) * blkSize]; 112 113 cacheTracking.init(head, tail); 114} 115 116void 117FALRU::regStats() 118{ 119 BaseTags::regStats(); 120 cacheTracking.regStats(name()); 121} 122 123void 124FALRU::invalidate(CacheBlk *blk) 125{ 126 // Erase block entry reference in the hash table
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129 130 // Sanity check; only one block reference should be erased 131 assert(num_erased == 1); 132 133 // Invalidate block entry. Must be done after the hash is erased 134 BaseTags::invalidate(blk); 135 136 // Decrease the number of tags in use 137 tagsInUse--; 138 139 // Move the block to the tail to make it the next victim 140 moveToTail((FALRUBlk*)blk); 141} 142 143CacheBlk* 144FALRU::accessBlock(Addr addr, bool is_secure, Cycles &lat) 145{ 146 return accessBlock(addr, is_secure, lat, 0); 147} 148 149CacheBlk* 150FALRU::accessBlock(Addr addr, bool is_secure, Cycles &lat, 151 CachesMask *in_caches_mask) 152{ 153 CachesMask mask = 0; 154 FALRUBlk* blk = static_cast<FALRUBlk*>(findBlock(addr, is_secure)); 155 156 if (blk && blk->isValid()) { 157 // If a cache hit 158 lat = accessLatency; 159 // Check if the block to be accessed is available. If not, 160 // apply the accessLatency on top of block->whenReady. 161 if (blk->whenReady > curTick() && 162 cache->ticksToCycles(blk->whenReady - curTick()) > 163 accessLatency) { 164 lat = cache->ticksToCycles(blk->whenReady - curTick()) + 165 accessLatency; 166 } 167 mask = blk->inCachesMask; 168 169 moveToHead(blk); 170 } else { 171 // If a cache miss 172 lat = lookupLatency; 173 } 174 if (in_caches_mask) { 175 *in_caches_mask = mask; 176 } 177 178 cacheTracking.recordAccess(blk); 179 180 return blk; 181} 182 183CacheBlk* 184FALRU::findBlock(Addr addr, bool is_secure) const 185{ 186 FALRUBlk* blk = nullptr; 187 188 Addr tag = extractTag(addr); 189 auto iter = tagHash.find(std::make_pair(tag, is_secure)); 190 if (iter != tagHash.end()) { 191 blk = (*iter).second; 192 } 193 194 if (blk && blk->isValid()) { 195 assert(blk->tag == tag); 196 assert(blk->isSecure() == is_secure); 197 } 198 199 return blk; 200} 201 202ReplaceableEntry* 203FALRU::findBlockBySetAndWay(int set, int way) const 204{ 205 assert(set == 0); 206 return &blks[way]; 207} 208 209CacheBlk* 210FALRU::findVictim(Addr addr, const bool is_secure, 211 std::vector<CacheBlk*>& evict_blks) const 212{ 213 // The victim is always stored on the tail for the FALRU 214 FALRUBlk* victim = tail; 215 216 // There is only one eviction for this replacement 217 evict_blks.push_back(victim); 218 219 return victim; 220} 221 222void 223FALRU::insertBlock(const Addr addr, const bool is_secure, 224 const int src_master_ID, const uint32_t task_ID, 225 CacheBlk *blk) 226{ 227 FALRUBlk* falruBlk = static_cast<FALRUBlk*>(blk); 228 229 // Make sure block is not present in the cache 230 assert(falruBlk->inCachesMask == 0); 231 232 // Do common block insertion functionality 233 BaseTags::insertBlock(addr, is_secure, src_master_ID, task_ID, blk); 234 235 // Increment tag counter 236 tagsInUse++; 237 238 // New block is the MRU 239 moveToHead(falruBlk); 240 241 // Insert new block in the hash table 242 tagHash[std::make_pair(blk->tag, blk->isSecure())] = falruBlk; 243} 244 245void 246FALRU::moveToHead(FALRUBlk *blk) 247{ 248 // If block is not already head, do the moving 249 if (blk != head) { 250 cacheTracking.moveBlockToHead(blk); 251 // If block is tail, set previous block as new tail 252 if (blk == tail){ 253 assert(blk->next == nullptr); 254 tail = blk->prev; 255 tail->next = nullptr; 256 // Inform block's surrounding blocks that it has been moved 257 } else { 258 blk->prev->next = blk->next; 259 blk->next->prev = blk->prev; 260 } 261 262 // Swap pointers 263 blk->next = head; 264 blk->prev = nullptr; 265 head->prev = blk; 266 head = blk; 267 268 cacheTracking.check(head, tail); 269 } 270} 271 272void 273FALRU::moveToTail(FALRUBlk *blk) 274{ 275 // If block is not already tail, do the moving 276 if (blk != tail) { 277 cacheTracking.moveBlockToTail(blk); 278 // If block is head, set next block as new head 279 if (blk == head){ 280 assert(blk->prev == nullptr); 281 head = blk->next; 282 head->prev = nullptr; 283 // Inform block's surrounding blocks that it has been moved 284 } else { 285 blk->prev->next = blk->next; 286 blk->next->prev = blk->prev; 287 } 288 289 // Swap pointers 290 blk->prev = tail; 291 blk->next = nullptr; 292 tail->next = blk; 293 tail = blk; 294 295 cacheTracking.check(head, tail); 296 } 297} 298 299FALRU * 300FALRUParams::create() 301{ 302 return new FALRU(this); 303} 304 305void 306FALRU::CacheTracking::check(const FALRUBlk *head, const FALRUBlk *tail) const 307{ 308#ifdef FALRU_DEBUG 309 const FALRUBlk* blk = head; 310 unsigned curr_size = 0; 311 unsigned tracked_cache_size = minTrackedSize; 312 CachesMask in_caches_mask = inAllCachesMask; 313 int j = 0; 314 315 while (blk) { 316 panic_if(blk->inCachesMask != in_caches_mask, "Expected cache mask " 317 "%x found %x", blk->inCachesMask, in_caches_mask); 318 319 curr_size += blkSize; 320 if (curr_size == tracked_cache_size && blk != tail) { 321 panic_if(boundaries[j] != blk, "Unexpected boundary for the %d-th " 322 "cache", j); 323 tracked_cache_size <<= 1; 324 // from this point, blocks fit only in the larger caches 325 in_caches_mask &= ~(1U << j); 326 ++j; 327 } 328 blk = blk->next; 329 } 330#endif // FALRU_DEBUG 331} 332 333void 334FALRU::CacheTracking::init(FALRUBlk *head, FALRUBlk *tail) 335{ 336 // early exit if we are not tracking any extra caches 337 FALRUBlk* blk = numTrackedCaches ? head : nullptr; 338 unsigned curr_size = 0; 339 unsigned tracked_cache_size = minTrackedSize; 340 CachesMask in_caches_mask = inAllCachesMask; 341 int j = 0; 342 343 while (blk) { 344 blk->inCachesMask = in_caches_mask; 345 346 curr_size += blkSize; 347 if (curr_size == tracked_cache_size && blk != tail) { 348 boundaries[j] = blk; 349 350 tracked_cache_size <<= 1; 351 // from this point, blocks fit only in the larger caches 352 in_caches_mask &= ~(1U << j); 353 ++j; 354 } 355 blk = blk->next; 356 } 357} 358 359 360void 361FALRU::CacheTracking::moveBlockToHead(FALRUBlk *blk) 362{ 363 // Get the mask of all caches, in which the block didn't fit 364 // before moving it to the head 365 CachesMask update_caches_mask = inAllCachesMask ^ blk->inCachesMask; 366 367 for (int i = 0; i < numTrackedCaches; i++) { 368 CachesMask current_cache_mask = 1U << i; 369 if (current_cache_mask & update_caches_mask) { 370 // if the ith cache didn't fit the block (before it is moved to 371 // the head), move the ith boundary 1 block closer to the 372 // MRU 373 boundaries[i]->inCachesMask &= ~current_cache_mask; 374 boundaries[i] = boundaries[i]->prev; 375 } else if (boundaries[i] == blk) { 376 // Make sure the boundary doesn't point to the block 377 // we are about to move 378 boundaries[i] = blk->prev; 379 } 380 } 381 382 // Make block reside in all caches 383 blk->inCachesMask = inAllCachesMask; 384} 385 386void 387FALRU::CacheTracking::moveBlockToTail(FALRUBlk *blk) 388{ 389 CachesMask update_caches_mask = blk->inCachesMask; 390 391 for (int i = 0; i < numTrackedCaches; i++) { 392 CachesMask current_cache_mask = 1U << i; 393 if (current_cache_mask & update_caches_mask) { 394 // if the ith cache fitted the block (before it is moved to 395 // the tail), move the ith boundary 1 block closer to the 396 // LRU 397 boundaries[i] = boundaries[i]->next; 398 if (boundaries[i] == blk) { 399 // Make sure the boundary doesn't point to the block 400 // we are about to move 401 boundaries[i] = blk->next; 402 } 403 boundaries[i]->inCachesMask |= current_cache_mask; 404 } 405 } 406 407 // The block now fits only in the actual cache 408 blk->inCachesMask = 0; 409} 410 411void 412FALRU::CacheTracking::recordAccess(FALRUBlk *blk) 413{ 414 for (int i = 0; i < numTrackedCaches; i++) { 415 if (blk && ((1U << i) & blk->inCachesMask)) { 416 hits[i]++; 417 } else { 418 misses[i]++; 419 } 420 } 421 422 // Record stats for the actual cache too 423 if (blk && blk->isValid()) { 424 hits[numTrackedCaches]++; 425 } else { 426 misses[numTrackedCaches]++; 427 } 428 429 accesses++; 430} 431 432void 433printSize(std::ostream &stream, size_t size) 434{ 435 static const char *SIZES[] = { "B", "kB", "MB", "GB", "TB", "ZB" }; 436 int div = 0; 437 while (size >= 1024 && div < (sizeof SIZES / sizeof *SIZES)) { 438 div++; 439 size >>= 10; 440 } 441 stream << size << SIZES[div]; 442} 443 444void 445FALRU::CacheTracking::regStats(std::string name) 446{ 447 hits 448 .init(numTrackedCaches + 1) 449 .name(name + ".falru_hits") 450 .desc("The number of hits in each cache size.") 451 ; 452 misses 453 .init(numTrackedCaches + 1) 454 .name(name + ".falru_misses") 455 .desc("The number of misses in each cache size.") 456 ; 457 accesses 458 .name(name + ".falru_accesses") 459 .desc("The number of accesses to the FA LRU cache.") 460 ; 461 462 for (unsigned i = 0; i < numTrackedCaches + 1; ++i) { 463 std::stringstream size_str; 464 printSize(size_str, minTrackedSize << i); 465 hits.subname(i, size_str.str()); 466 hits.subdesc(i, "Hits in a " + size_str.str() + " cache"); 467 misses.subname(i, size_str.str()); 468 misses.subdesc(i, "Misses in a " + size_str.str() + " cache"); 469 } 470}
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