base_set_assoc.hh revision 13220:78a8391a0f95
1/* 2 * Copyright (c) 2012-2014,2017 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) 2003-2005,2014 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 */ 42 43/** 44 * @file 45 * Declaration of a base set associative tag store. 46 */ 47 48#ifndef __MEM_CACHE_TAGS_BASE_SET_ASSOC_HH__ 49#define __MEM_CACHE_TAGS_BASE_SET_ASSOC_HH__ 50 51#include <functional> 52#include <string> 53#include <vector> 54 55#include "base/logging.hh" 56#include "base/types.hh" 57#include "debug/CacheRepl.hh" 58#include "mem/cache/base.hh" 59#include "mem/cache/blk.hh" 60#include "mem/cache/replacement_policies/base.hh" 61#include "mem/cache/tags/base.hh" 62#include "mem/cache/tags/indexing_policies/base.hh" 63#include "params/BaseSetAssoc.hh" 64 65/** 66 * A basic cache tag store. 67 * @sa \ref gem5MemorySystem "gem5 Memory System" 68 * 69 * The BaseSetAssoc placement policy divides the cache into s sets of w 70 * cache lines (ways). 71 */ 72class BaseSetAssoc : public BaseTags 73{ 74 protected: 75 /** The allocatable associativity of the cache (alloc mask). */ 76 unsigned allocAssoc; 77 78 /** The cache blocks. */ 79 std::vector<CacheBlk> blks; 80 81 /** Whether tags and data are accessed sequentially. */ 82 const bool sequentialAccess; 83 84 /** Replacement policy */ 85 BaseReplacementPolicy *replacementPolicy; 86 87 public: 88 /** Convenience typedef. */ 89 typedef BaseSetAssocParams Params; 90 91 /** 92 * Construct and initialize this tag store. 93 */ 94 BaseSetAssoc(const Params *p); 95 96 /** 97 * Destructor 98 */ 99 virtual ~BaseSetAssoc() {}; 100 101 /** 102 * Initialize blocks and set the parent cache back pointer. 103 * 104 * @param _cache Pointer to parent cache. 105 */ 106 void init(BaseCache *_cache) override; 107 108 /** 109 * This function updates the tags when a block is invalidated. It also 110 * updates the replacement data. 111 * 112 * @param blk The block to invalidate. 113 */ 114 void invalidate(CacheBlk *blk) override; 115 116 /** 117 * Access block and update replacement data. May not succeed, in which case 118 * nullptr is returned. This has all the implications of a cache 119 * access and should only be used as such. Returns the access latency as a 120 * side effect. 121 * @param addr The address to find. 122 * @param is_secure True if the target memory space is secure. 123 * @param lat The access latency. 124 * @return Pointer to the cache block if found. 125 */ 126 CacheBlk* accessBlock(Addr addr, bool is_secure, Cycles &lat) override 127 { 128 CacheBlk *blk = findBlock(addr, is_secure); 129 130 // Access all tags in parallel, hence one in each way. The data side 131 // either accesses all blocks in parallel, or one block sequentially on 132 // a hit. Sequential access with a miss doesn't access data. 133 tagAccesses += allocAssoc; 134 if (sequentialAccess) { 135 if (blk != nullptr) { 136 dataAccesses += 1; 137 } 138 } else { 139 dataAccesses += allocAssoc; 140 } 141 142 if (blk != nullptr) { 143 // If a cache hit 144 lat = accessLatency; 145 // Check if the block to be accessed is available. If not, 146 // apply the accessLatency on top of block->whenReady. 147 if (blk->whenReady > curTick() && 148 cache->ticksToCycles(blk->whenReady - curTick()) > 149 accessLatency) { 150 lat = cache->ticksToCycles(blk->whenReady - curTick()) + 151 accessLatency; 152 } 153 154 // Update number of references to accessed block 155 blk->refCount++; 156 157 // Update replacement data of accessed block 158 replacementPolicy->touch(blk->replacementData); 159 } else { 160 // If a cache miss 161 lat = lookupLatency; 162 } 163 164 return blk; 165 } 166 167 /** 168 * Find replacement victim based on address. The list of evicted blocks 169 * only contains the victim. 170 * 171 * @param addr Address to find a victim for. 172 * @param is_secure True if the target memory space is secure. 173 * @param evict_blks Cache blocks to be evicted. 174 * @return Cache block to be replaced. 175 */ 176 CacheBlk* findVictim(Addr addr, const bool is_secure, 177 std::vector<CacheBlk*>& evict_blks) const override 178 { 179 // Get possible entries to be victimized 180 const std::vector<ReplaceableEntry*> entries = 181 indexingPolicy->getPossibleEntries(addr); 182 183 // Choose replacement victim from replacement candidates 184 CacheBlk* victim = static_cast<CacheBlk*>(replacementPolicy->getVictim( 185 entries)); 186 187 // There is only one eviction for this replacement 188 evict_blks.push_back(victim); 189 190 DPRINTF(CacheRepl, "set %x, way %x: selecting blk for replacement\n", 191 victim->getSet(), victim->getWay()); 192 193 return victim; 194 } 195 196 /** 197 * Insert the new block into the cache and update replacement data. 198 * 199 * @param addr Address of the block. 200 * @param is_secure Whether the block is in secure space or not. 201 * @param src_master_ID The source requestor ID. 202 * @param task_ID The new task ID. 203 * @param blk The block to update. 204 */ 205 void insertBlock(const Addr addr, const bool is_secure, 206 const int src_master_ID, const uint32_t task_ID, 207 CacheBlk *blk) override 208 { 209 // Insert block 210 BaseTags::insertBlock(addr, is_secure, src_master_ID, task_ID, blk); 211 212 // Increment tag counter 213 tagsInUse++; 214 215 // Update replacement policy 216 replacementPolicy->reset(blk->replacementData); 217 } 218 219 /** 220 * Limit the allocation for the cache ways. 221 * @param ways The maximum number of ways available for replacement. 222 */ 223 virtual void setWayAllocationMax(int ways) override 224 { 225 fatal_if(ways < 1, "Allocation limit must be greater than zero"); 226 allocAssoc = ways; 227 } 228 229 /** 230 * Get the way allocation mask limit. 231 * @return The maximum number of ways available for replacement. 232 */ 233 virtual int getWayAllocationMax() const override 234 { 235 return allocAssoc; 236 } 237 238 /** 239 * Regenerate the block address from the tag and indexing location. 240 * 241 * @param block The block. 242 * @return the block address. 243 */ 244 Addr regenerateBlkAddr(const CacheBlk* blk) const override 245 { 246 return indexingPolicy->regenerateAddr(blk->tag, blk); 247 } 248 249 void forEachBlk(std::function<void(CacheBlk &)> visitor) override { 250 for (CacheBlk& blk : blks) { 251 visitor(blk); 252 } 253 } 254 255 bool anyBlk(std::function<bool(CacheBlk &)> visitor) override { 256 for (CacheBlk& blk : blks) { 257 if (visitor(blk)) { 258 return true; 259 } 260 } 261 return false; 262 } 263}; 264 265#endif //__MEM_CACHE_TAGS_BASE_SET_ASSOC_HH__ 266