sector_tags.cc revision 13418:08101e89101e
1/* 2 * Copyright (c) 2018 Inria 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: Daniel Carvalho 29 */ 30 31/** 32 * @file 33 * Definitions of a sector tag store. 34 */ 35 36#include "mem/cache/tags/sector_tags.hh" 37 38#include <cassert> 39#include <memory> 40#include <string> 41 42#include "base/intmath.hh" 43#include "base/logging.hh" 44#include "base/types.hh" 45#include "mem/cache/base.hh" 46#include "mem/cache/replacement_policies/base.hh" 47#include "mem/cache/replacement_policies/replaceable_entry.hh" 48#include "mem/cache/tags/indexing_policies/base.hh" 49 50SectorTags::SectorTags(const SectorTagsParams *p) 51 : BaseTags(p), allocAssoc(p->assoc), 52 sequentialAccess(p->sequential_access), 53 replacementPolicy(p->replacement_policy), 54 numBlocksPerSector(p->num_blocks_per_sector), 55 numSectors(numBlocks / p->num_blocks_per_sector), blks(numBlocks), 56 secBlks(numSectors), sectorShift(floorLog2(blkSize)), 57 sectorMask(numBlocksPerSector - 1) 58{ 59 // Check parameters 60 fatal_if(blkSize < 4 || !isPowerOf2(blkSize), 61 "Block size must be at least 4 and a power of 2"); 62 fatal_if(!isPowerOf2(numBlocksPerSector), 63 "# of blocks per sector must be non-zero and a power of 2"); 64} 65 66void 67SectorTags::tagsInit(BaseCache* cache) 68{ 69 // Set parent cache 70 setCache(cache); 71 72 // Initialize all blocks 73 unsigned blk_index = 0; // index into blks array 74 for (unsigned sec_blk_index = 0; sec_blk_index < numSectors; 75 sec_blk_index++) 76 { 77 // Locate next cache sector 78 SectorBlk* sec_blk = &secBlks[sec_blk_index]; 79 80 // Link block to indexing policy 81 indexingPolicy->setEntry(sec_blk, sec_blk_index); 82 83 // Associate a replacement data entry to the sector 84 sec_blk->replacementData = replacementPolicy->instantiateEntry(); 85 86 // Initialize all blocks in this sector 87 sec_blk->blks.resize(numBlocksPerSector); 88 for (unsigned k = 0; k < numBlocksPerSector; ++k){ 89 // Select block within the set to be linked 90 SectorSubBlk*& blk = sec_blk->blks[k]; 91 92 // Locate next cache block 93 blk = &blks[blk_index]; 94 95 // Associate a data chunk to the block 96 blk->data = &dataBlks[blkSize*blk_index]; 97 98 // Associate sector block to this block 99 blk->setSectorBlock(sec_blk); 100 101 // Associate the sector replacement data to this block 102 blk->replacementData = sec_blk->replacementData; 103 104 // Set its index and sector offset 105 blk->setSectorOffset(k); 106 107 // Update block index 108 ++blk_index; 109 } 110 } 111} 112 113void 114SectorTags::invalidate(CacheBlk *blk) 115{ 116 BaseTags::invalidate(blk); 117 118 // Get block's sector 119 SectorSubBlk* sub_blk = static_cast<SectorSubBlk*>(blk); 120 const SectorBlk* sector_blk = sub_blk->getSectorBlock(); 121 122 // When a block in a sector is invalidated, it does not make the tag 123 // invalid automatically, as there might be other blocks in the sector 124 // using it. The tag is invalidated only when there is a single block 125 // in the sector. 126 if (!sector_blk->isValid()) { 127 // Decrease the number of tags in use 128 tagsInUse--; 129 130 // Invalidate replacement data, as we're invalidating the sector 131 replacementPolicy->invalidate(sector_blk->replacementData); 132 } 133} 134 135CacheBlk* 136SectorTags::accessBlock(Addr addr, bool is_secure, Cycles &lat) 137{ 138 CacheBlk *blk = findBlock(addr, is_secure); 139 140 // Access all tags in parallel, hence one in each way. The data side 141 // either accesses all blocks in parallel, or one block sequentially on 142 // a hit. Sequential access with a miss doesn't access data. 143 tagAccesses += allocAssoc; 144 if (sequentialAccess) { 145 if (blk != nullptr) { 146 dataAccesses += 1; 147 } 148 } else { 149 dataAccesses += allocAssoc*numBlocksPerSector; 150 } 151 152 // If a cache hit 153 if (blk != nullptr) { 154 // Update number of references to accessed block 155 blk->refCount++; 156 157 // Get block's sector 158 SectorSubBlk* sub_blk = static_cast<SectorSubBlk*>(blk); 159 const SectorBlk* sector_blk = sub_blk->getSectorBlock(); 160 161 // Update replacement data of accessed block, which is shared with 162 // the whole sector it belongs to 163 replacementPolicy->touch(sector_blk->replacementData); 164 } 165 166 // The tag lookup latency is the same for a hit or a miss 167 lat = lookupLatency; 168 169 return blk; 170} 171 172void 173SectorTags::insertBlock(const Addr addr, const bool is_secure, 174 const int src_master_ID, const uint32_t task_ID, 175 CacheBlk *blk) 176{ 177 // Do common block insertion functionality 178 BaseTags::insertBlock(addr, is_secure, src_master_ID, task_ID, blk); 179 180 // Get block's sector 181 SectorSubBlk* sub_blk = static_cast<SectorSubBlk*>(blk); 182 const SectorBlk* sector_blk = sub_blk->getSectorBlock(); 183 184 // When a block is inserted, the tag is only a newly used tag if the 185 // sector was not previously present in the cache. 186 // This assumes BaseTags::insertBlock does not set the valid bit. 187 if (sector_blk->isValid()) { 188 // An existing entry's replacement data is just updated 189 replacementPolicy->touch(sector_blk->replacementData); 190 } else { 191 // Increment tag counter 192 tagsInUse++; 193 194 // A new entry resets the replacement data 195 replacementPolicy->reset(sector_blk->replacementData); 196 } 197} 198 199CacheBlk* 200SectorTags::findBlock(Addr addr, bool is_secure) const 201{ 202 // Extract sector tag 203 const Addr tag = extractTag(addr); 204 205 // The address can only be mapped to a specific location of a sector 206 // due to sectors being composed of contiguous-address entries 207 const Addr offset = extractSectorOffset(addr); 208 209 // Find all possible sector entries that may contain the given address 210 const std::vector<ReplaceableEntry*> entries = 211 indexingPolicy->getPossibleEntries(addr); 212 213 // Search for block 214 for (const auto& sector : entries) { 215 auto blk = static_cast<SectorBlk*>(sector)->blks[offset]; 216 if (blk->getTag() == tag && blk->isValid() && 217 blk->isSecure() == is_secure) { 218 return blk; 219 } 220 } 221 222 // Did not find block 223 return nullptr; 224} 225 226CacheBlk* 227SectorTags::findVictim(Addr addr, const bool is_secure, 228 std::vector<CacheBlk*>& evict_blks) const 229{ 230 // Get possible entries to be victimized 231 const std::vector<ReplaceableEntry*> sector_entries = 232 indexingPolicy->getPossibleEntries(addr); 233 234 // Check if the sector this address belongs to has been allocated 235 Addr tag = extractTag(addr); 236 SectorBlk* victim_sector = nullptr; 237 for (const auto& sector : sector_entries) { 238 SectorBlk* sector_blk = static_cast<SectorBlk*>(sector); 239 if ((tag == sector_blk->getTag()) && sector_blk->isValid() && 240 (is_secure == sector_blk->isSecure())){ 241 victim_sector = sector_blk; 242 break; 243 } 244 } 245 246 // If the sector is not present 247 if (victim_sector == nullptr){ 248 // Choose replacement victim from replacement candidates 249 victim_sector = static_cast<SectorBlk*>(replacementPolicy->getVictim( 250 sector_entries)); 251 } 252 253 // Get the entry of the victim block within the sector 254 SectorSubBlk* victim = victim_sector->blks[extractSectorOffset(addr)]; 255 256 // Get evicted blocks. Blocks are only evicted if the sectors mismatch and 257 // the currently existing sector is valid. 258 if ((tag == victim_sector->getTag()) && 259 (is_secure == victim_sector->isSecure())){ 260 // It would be a hit if victim was valid, and upgrades do not call 261 // findVictim, so it cannot happen 262 assert(!victim->isValid()); 263 } else { 264 // The whole sector must be evicted to make room for the new sector 265 for (const auto& blk : victim_sector->blks){ 266 evict_blks.push_back(blk); 267 } 268 } 269 270 return victim; 271} 272 273int 274SectorTags::extractSectorOffset(Addr addr) const 275{ 276 return (addr >> sectorShift) & sectorMask; 277} 278 279Addr 280SectorTags::regenerateBlkAddr(const CacheBlk* blk) const 281{ 282 const SectorSubBlk* blk_cast = static_cast<const SectorSubBlk*>(blk); 283 const SectorBlk* sec_blk = blk_cast->getSectorBlock(); 284 const Addr sec_addr = indexingPolicy->regenerateAddr(blk->tag, sec_blk); 285 return sec_addr | ((Addr)blk_cast->getSectorOffset() << sectorShift); 286} 287 288void 289SectorTags::forEachBlk(std::function<void(CacheBlk &)> visitor) 290{ 291 for (SectorSubBlk& blk : blks) { 292 visitor(blk); 293 } 294} 295 296bool 297SectorTags::anyBlk(std::function<bool(CacheBlk &)> visitor) 298{ 299 for (SectorSubBlk& blk : blks) { 300 if (visitor(blk)) { 301 return true; 302 } 303 } 304 return false; 305} 306 307SectorTags * 308SectorTagsParams::create() 309{ 310 // There must be a indexing policy 311 fatal_if(!indexing_policy, "An indexing policy is required"); 312 313 return new SectorTags(this); 314} 315