spatio_temporal_memory_streaming.cc revision 13786:860c780d9f30
113277Sgabeblack@google.com/** 213277Sgabeblack@google.com * Copyright (c) 2019 Metempsy Technology Consulting 313277Sgabeblack@google.com * All rights reserved. 413277Sgabeblack@google.com * 513277Sgabeblack@google.com * Redistribution and use in source and binary forms, with or without 613277Sgabeblack@google.com * modification, are permitted provided that the following conditions are 713277Sgabeblack@google.com * met: redistributions of source code must retain the above copyright 813277Sgabeblack@google.com * notice, this list of conditions and the following disclaimer; 913277Sgabeblack@google.com * redistributions in binary form must reproduce the above copyright 1013277Sgabeblack@google.com * notice, this list of conditions and the following disclaimer in the 1113277Sgabeblack@google.com * documentation and/or other materials provided with the distribution; 1213277Sgabeblack@google.com * neither the name of the copyright holders nor the names of its 1313277Sgabeblack@google.com * contributors may be used to endorse or promote products derived from 1413277Sgabeblack@google.com * this software without specific prior written permission. 1513277Sgabeblack@google.com * 1613277Sgabeblack@google.com * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 1713277Sgabeblack@google.com * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 1813277Sgabeblack@google.com * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 1913277Sgabeblack@google.com * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 2013277Sgabeblack@google.com * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 2113277Sgabeblack@google.com * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 2213277Sgabeblack@google.com * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 2313277Sgabeblack@google.com * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 2413277Sgabeblack@google.com * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 2513277Sgabeblack@google.com * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 2613277Sgabeblack@google.com * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 2713277Sgabeblack@google.com * 2813277Sgabeblack@google.com * Authors: Javier Bueno 2913277Sgabeblack@google.com */ 3013277Sgabeblack@google.com 3113277Sgabeblack@google.com#include "mem/cache/prefetch/spatio_temporal_memory_streaming.hh" 3213277Sgabeblack@google.com 3313324Sgabeblack@google.com#include "debug/HWPrefetch.hh" 3413277Sgabeblack@google.com#include "mem/cache/prefetch/associative_set_impl.hh" 3513277Sgabeblack@google.com#include "params/STeMSPrefetcher.hh" 3613277Sgabeblack@google.com 3713277Sgabeblack@google.comSTeMSPrefetcher::STeMSPrefetcher(const STeMSPrefetcherParams *p) 3813277Sgabeblack@google.com : QueuedPrefetcher(p), spatialRegionSize(p->spatial_region_size), 3913277Sgabeblack@google.com spatialRegionSizeBits(floorLog2(p->spatial_region_size)), 4013277Sgabeblack@google.com reconstructionEntries(p->reconstruction_entries), 4113277Sgabeblack@google.com activeGenerationTable(p->active_generation_table_assoc, 4213277Sgabeblack@google.com p->active_generation_table_entries, 4313277Sgabeblack@google.com p->active_generation_table_indexing_policy, 4413277Sgabeblack@google.com p->active_generation_table_replacement_policy, 4513277Sgabeblack@google.com ActiveGenerationTableEntry( 4613277Sgabeblack@google.com spatialRegionSize / blkSize)), 4713277Sgabeblack@google.com patternSequenceTable(p->pattern_sequence_table_assoc, 4813277Sgabeblack@google.com p->pattern_sequence_table_entries, 4913277Sgabeblack@google.com p->pattern_sequence_table_indexing_policy, 5013277Sgabeblack@google.com p->pattern_sequence_table_replacement_policy, 5113277Sgabeblack@google.com ActiveGenerationTableEntry( 5213277Sgabeblack@google.com spatialRegionSize / blkSize)), 5313277Sgabeblack@google.com rmob(p->region_miss_order_buffer_entries), rmobHead(0) 5413277Sgabeblack@google.com{ 5513277Sgabeblack@google.com fatal_if(!isPowerOf2(spatialRegionSize), 5613277Sgabeblack@google.com "The spatial region size must be a power of 2."); 5713277Sgabeblack@google.com} 5813277Sgabeblack@google.com 5913277Sgabeblack@google.comvoid 6013277Sgabeblack@google.comSTeMSPrefetcher::checkForActiveGenerationsEnd() { 6113277Sgabeblack@google.com // This prefetcher operates attached to the L1 and it observes all 6213277Sgabeblack@google.com // accesses, this guarantees that no evictions are missed 6313277Sgabeblack@google.com 6413277Sgabeblack@google.com // Iterate over all entries, if any recorded cacheline has been evicted, 6513277Sgabeblack@google.com // the generation finishes, move the entry to the PST 6613277Sgabeblack@google.com for (auto &agt_entry : activeGenerationTable) { 6713277Sgabeblack@google.com if (agt_entry.isValid()) { 6813277Sgabeblack@google.com bool generation_ended = false; 6913277Sgabeblack@google.com bool sr_is_secure = agt_entry.isSecure(); 7013277Sgabeblack@google.com for (auto &seq_entry : agt_entry.sequence) { 7113277Sgabeblack@google.com if (seq_entry.counter > 0) { 7213495Sgabeblack@google.com Addr cache_addr = 7313495Sgabeblack@google.com agt_entry.paddress + seq_entry.offset * blkSize; 7413495Sgabeblack@google.com if (!inCache(cache_addr, sr_is_secure) && 7513495Sgabeblack@google.com !inMissQueue(cache_addr, sr_is_secure)) { 7613495Sgabeblack@google.com generation_ended = true; 7713495Sgabeblack@google.com break; 7813495Sgabeblack@google.com } 7913495Sgabeblack@google.com } 8013495Sgabeblack@google.com } 8113495Sgabeblack@google.com if (generation_ended) { 8213495Sgabeblack@google.com // PST is indexed using the PC (secure bit is unused) 8313495Sgabeblack@google.com ActiveGenerationTableEntry *pst_entry = 8413495Sgabeblack@google.com patternSequenceTable.findEntry(agt_entry.pc, 8513495Sgabeblack@google.com false /*unused*/); 8613277Sgabeblack@google.com if (pst_entry == nullptr) { 8713277Sgabeblack@google.com // Tipically an entry will not exist 8813277Sgabeblack@google.com pst_entry = patternSequenceTable.findVictim(agt_entry.pc); 8913277Sgabeblack@google.com assert(pst_entry != nullptr); 9013277Sgabeblack@google.com patternSequenceTable.insertEntry(agt_entry.pc, 9113277Sgabeblack@google.com false /*unused*/, pst_entry); 9213277Sgabeblack@google.com } else { 9313277Sgabeblack@google.com patternSequenceTable.accessEntry(pst_entry); 9413277Sgabeblack@google.com } 9513278Sgabeblack@google.com // If the entry existed, this will update the values, if not, 9613277Sgabeblack@google.com // this also sets the values of the entry 9713277Sgabeblack@google.com pst_entry->update(agt_entry); 9813277Sgabeblack@google.com // Free the AGT entry 9913277Sgabeblack@google.com agt_entry.setInvalid(); 10013277Sgabeblack@google.com } 10113277Sgabeblack@google.com } 10213277Sgabeblack@google.com } 10313324Sgabeblack@google.com} 10413277Sgabeblack@google.com 10513277Sgabeblack@google.comvoid 10613277Sgabeblack@google.comSTeMSPrefetcher::addToRMOB(Addr sr_addr, Addr pst_addr, unsigned int delta) 10713277Sgabeblack@google.com{ 10813277Sgabeblack@google.com RegionMissOrderBufferEntry &rmob_entry = rmob[rmobHead]; 10913277Sgabeblack@google.com rmobHead = (rmobHead + 1) % rmob.size(); 11013277Sgabeblack@google.com 11113277Sgabeblack@google.com rmob_entry.srAddress = sr_addr; 11213277Sgabeblack@google.com rmob_entry.pstAddress = pst_addr; 11313277Sgabeblack@google.com rmob_entry.delta = delta; 11413277Sgabeblack@google.com rmob_entry.valid = true; 11513277Sgabeblack@google.com} 11613277Sgabeblack@google.com 11713277Sgabeblack@google.comvoid 11813277Sgabeblack@google.comSTeMSPrefetcher::calculatePrefetch(const PrefetchInfo &pfi, 11913277Sgabeblack@google.com std::vector<AddrPriority> &addresses) 12013277Sgabeblack@google.com{ 12113277Sgabeblack@google.com if (!pfi.hasPC()) { 12213277Sgabeblack@google.com DPRINTF(HWPrefetch, "Ignoring request with no PC.\n"); 12313277Sgabeblack@google.com return; 12413277Sgabeblack@google.com } 12513277Sgabeblack@google.com 12613277Sgabeblack@google.com Addr pc = pfi.getPC(); 12713277Sgabeblack@google.com bool is_secure = pfi.isSecure(); 12813277Sgabeblack@google.com // Spatial region address 12913277Sgabeblack@google.com Addr sr_addr = pfi.getAddr() / spatialRegionSize; 13013277Sgabeblack@google.com Addr paddr = pfi.getPaddr(); 13113277Sgabeblack@google.com 13213277Sgabeblack@google.com // Offset in cachelines within the spatial region 13313277Sgabeblack@google.com Addr sr_offset = (pfi.getAddr() % spatialRegionSize) / blkSize; 13413277Sgabeblack@google.com 13513277Sgabeblack@google.com // Check if any active generation has ended 13613277Sgabeblack@google.com checkForActiveGenerationsEnd(); 13713277Sgabeblack@google.com 13813277Sgabeblack@google.com ActiveGenerationTableEntry *agt_entry = 13913277Sgabeblack@google.com activeGenerationTable.findEntry(sr_addr, is_secure); 14013277Sgabeblack@google.com if (agt_entry != nullptr) { 14113277Sgabeblack@google.com // found an entry in the AGT, entry is currently being recorded, 14213277Sgabeblack@google.com // add the offset 14313277Sgabeblack@google.com activeGenerationTable.accessEntry(agt_entry); 14413277Sgabeblack@google.com agt_entry->addOffset(sr_offset); 14513277Sgabeblack@google.com lastTriggerCounter += 1; 14613277Sgabeblack@google.com } else { 14713277Sgabeblack@google.com // Not found, this is the first access (Trigger access) 14813277Sgabeblack@google.com 14913277Sgabeblack@google.com // Add entry to RMOB 15013277Sgabeblack@google.com Addr pst_addr = (pc << spatialRegionSizeBits) + sr_offset; 15113277Sgabeblack@google.com addToRMOB(sr_addr, pst_addr, lastTriggerCounter); 15213277Sgabeblack@google.com // Reset last trigger counter 15313277Sgabeblack@google.com lastTriggerCounter = 0; 15413277Sgabeblack@google.com 15513277Sgabeblack@google.com // allocate a new AGT entry 15613277Sgabeblack@google.com agt_entry = activeGenerationTable.findVictim(sr_addr); 15713277Sgabeblack@google.com assert(agt_entry != nullptr); 15813277Sgabeblack@google.com activeGenerationTable.insertEntry(sr_addr, is_secure, agt_entry); 15913277Sgabeblack@google.com agt_entry->pc = pc; 16013277Sgabeblack@google.com agt_entry->paddress = paddr; 16113277Sgabeblack@google.com agt_entry->addOffset(sr_offset); 16213277Sgabeblack@google.com } 16313277Sgabeblack@google.com // increase the seq Counter for other entries 16413277Sgabeblack@google.com for (auto &agt_e : activeGenerationTable) { 16513277Sgabeblack@google.com if (agt_e.isValid() && agt_entry != &agt_e) { 16613277Sgabeblack@google.com agt_e.seqCounter += 1; 16713277Sgabeblack@google.com } 16813277Sgabeblack@google.com } 16913277Sgabeblack@google.com 17013277Sgabeblack@google.com // Prefetch generation: if this is a miss, search for the most recent 17113277Sgabeblack@google.com // entry in the RMOB, and reconstruct the registered access sequence 17213277Sgabeblack@google.com if (pfi.isCacheMiss()) { 17313277Sgabeblack@google.com for (unsigned int idx = (rmobHead - 1) % rmob.size(); 17413277Sgabeblack@google.com idx != rmobHead && rmob[idx].valid; 17513277Sgabeblack@google.com idx = (idx - 1) % rmob.size()) 17613277Sgabeblack@google.com { 17713277Sgabeblack@google.com if (rmob[idx].srAddress == sr_addr) { 17813277Sgabeblack@google.com // reconstruct the access sequence 17913277Sgabeblack@google.com reconstructSequence(idx, addresses); 18013277Sgabeblack@google.com break; 18113277Sgabeblack@google.com } 18213288Sgabeblack@google.com } 18313277Sgabeblack@google.com } 18413277Sgabeblack@google.com} 18513277Sgabeblack@google.com 18613277Sgabeblack@google.comvoid 18713277Sgabeblack@google.comSTeMSPrefetcher::reconstructSequence(unsigned int rmob_idx, 18813277Sgabeblack@google.com std::vector<AddrPriority> &addresses) 18913288Sgabeblack@google.com{ 19013288Sgabeblack@google.com std::vector<Addr> reconstruction(reconstructionEntries, MaxAddr); 19113288Sgabeblack@google.com unsigned int idx = 0; 19213288Sgabeblack@google.com // process rmob entries from rmob_idx (most recent with 19313288Sgabeblack@google.com // address = sr_addr) to the last one (rmobHead) 19413288Sgabeblack@google.com for (int i = rmob_idx; 19513288Sgabeblack@google.com i != rmobHead && idx < reconstructionEntries; 19613288Sgabeblack@google.com i = (i + 1) % rmob.size()) 19713288Sgabeblack@google.com { 19813288Sgabeblack@google.com reconstruction[idx] = rmob[i].srAddress * spatialRegionSize; 19913288Sgabeblack@google.com unsigned int next_i = (i + 1) % rmob.size(); 20013288Sgabeblack@google.com idx += rmob[next_i].delta + 1; 20113288Sgabeblack@google.com } 20213277Sgabeblack@google.com // Now query the PST with the PC of each RMOB entry 203 idx = 0; 204 for (int i = rmob_idx; 205 i != rmobHead && idx < reconstructionEntries; 206 i = (i + 1) % rmob.size()) 207 { 208 ActiveGenerationTableEntry *pst_entry = 209 patternSequenceTable.findEntry(rmob[i].pstAddress, 210 false /* unused */); 211 if (pst_entry != nullptr) { 212 patternSequenceTable.accessEntry(pst_entry); 213 for (auto &seq_entry : pst_entry->sequence) { 214 if (seq_entry.counter > 1) { 215 // 3-bit counter: high enough confidence with a 216 // value greater than 1 217 Addr rec_addr = rmob[i].srAddress * spatialRegionSize + 218 seq_entry.offset; 219 unsigned ridx = idx + seq_entry.delta; 220 // Try to use the corresponding position, if it has been 221 // already used, look the surrounding positions 222 if (ridx < reconstructionEntries && 223 reconstruction[ridx] == MaxAddr) { 224 reconstruction[ridx] = rec_addr; 225 } else if ((ridx + 1) < reconstructionEntries && 226 reconstruction[ridx + 1] == MaxAddr) { 227 reconstruction[ridx + 1] = rec_addr; 228 } else if ((ridx + 2) < reconstructionEntries && 229 reconstruction[ridx + 2] == MaxAddr) { 230 reconstruction[ridx + 2] = rec_addr; 231 } else if ((ridx > 0) && 232 ((ridx - 1) < reconstructionEntries) && 233 reconstruction[ridx - 1] == MaxAddr) { 234 reconstruction[ridx - 1] = rec_addr; 235 } else if ((ridx > 1) && 236 ((ridx - 2) < reconstructionEntries) && 237 reconstruction[ridx - 2] == MaxAddr) { 238 reconstruction[ridx - 2] = rec_addr; 239 } 240 } 241 } 242 } 243 unsigned int next_i = (i + 1) % rmob.size(); 244 idx += rmob[next_i].delta + 1; 245 } 246 for (Addr pf_addr : reconstruction) { 247 if (pf_addr != MaxAddr) { 248 addresses.push_back(AddrPriority(pf_addr, 0)); 249 } 250 } 251} 252 253STeMSPrefetcher * 254STeMSPrefetcherParams::create() 255{ 256 return new STeMSPrefetcher(this); 257} 258