base.cc revision 6105
1/* 2 * Copyright (c) 2005 The Regents of The University of Michigan 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: Ron Dreslinski 29 */ 30 31/** 32 * @file 33 * Hardware Prefetcher Definition. 34 */ 35 36#include "arch/isa_traits.hh" 37#include "base/trace.hh" 38#include "mem/cache/base.hh" 39#include "mem/cache/prefetch/base.hh" 40#include "mem/request.hh" 41#include <list> 42 43BasePrefetcher::BasePrefetcher(const BaseCacheParams *p) 44 : size(p->prefetcher_size), pageStop(!p->prefetch_past_page), 45 serialSquash(p->prefetch_serial_squash), 46 cacheCheckPush(p->prefetch_cache_check_push), 47 onlyData(p->prefetch_data_accesses_only) 48{ 49} 50 51void 52BasePrefetcher::setCache(BaseCache *_cache) 53{ 54 cache = _cache; 55 blkSize = cache->getBlockSize(); 56 _name = cache->name() + "-pf"; 57} 58 59void 60BasePrefetcher::regStats(const std::string &name) 61{ 62 pfIdentified 63 .name(name + ".prefetcher.num_hwpf_identified") 64 .desc("number of hwpf identified") 65 ; 66 67 pfMSHRHit 68 .name(name + ".prefetcher.num_hwpf_already_in_mshr") 69 .desc("number of hwpf that were already in mshr") 70 ; 71 72 pfCacheHit 73 .name(name + ".prefetcher.num_hwpf_already_in_cache") 74 .desc("number of hwpf that were already in the cache") 75 ; 76 77 pfBufferHit 78 .name(name + ".prefetcher.num_hwpf_already_in_prefetcher") 79 .desc("number of hwpf that were already in the prefetch queue") 80 ; 81 82 pfRemovedFull 83 .name(name + ".prefetcher.num_hwpf_evicted") 84 .desc("number of hwpf removed due to no buffer left") 85 ; 86 87 pfRemovedMSHR 88 .name(name + ".prefetcher.num_hwpf_removed_MSHR_hit") 89 .desc("number of hwpf removed because MSHR allocated") 90 ; 91 92 pfIssued 93 .name(name + ".prefetcher.num_hwpf_issued") 94 .desc("number of hwpf issued") 95 ; 96 97 pfSpanPage 98 .name(name + ".prefetcher.num_hwpf_span_page") 99 .desc("number of hwpf spanning a virtual page") 100 ; 101 102 pfSquashed 103 .name(name + ".prefetcher.num_hwpf_squashed_from_miss") 104 .desc("number of hwpf that got squashed due to a miss " 105 "aborting calculation time") 106 ; 107} 108 109inline bool 110BasePrefetcher::inCache(Addr addr) 111{ 112 if (cache->inCache(addr)) { 113 pfCacheHit++; 114 return true; 115 } 116 return false; 117} 118 119inline bool 120BasePrefetcher::inMissQueue(Addr addr) 121{ 122 if (cache->inMissQueue(addr)) { 123 pfMSHRHit++; 124 return true; 125 } 126 return false; 127} 128 129PacketPtr 130BasePrefetcher::getPacket() 131{ 132 DPRINTF(HWPrefetch, "Requesting a hw_pf to issue\n"); 133 134 if (pf.empty()) { 135 DPRINTF(HWPrefetch, "No HW_PF found\n"); 136 return NULL; 137 } 138 139 PacketPtr pkt; 140 bool keep_trying = false; 141 do { 142 pkt = *pf.begin(); 143 pf.pop_front(); 144 if (!cacheCheckPush) { 145 keep_trying = cache->inCache(pkt->getAddr()); 146 } 147 148 if (keep_trying) { 149 DPRINTF(HWPrefetch, "addr 0x%x in cache, skipping\n", 150 pkt->getAddr()); 151 delete pkt->req; 152 delete pkt; 153 } 154 155 if (pf.empty()) { 156 cache->deassertMemSideBusRequest(BaseCache::Request_PF); 157 if (keep_trying) { 158 return NULL; // None left, all were in cache 159 } 160 } 161 } while (keep_trying); 162 163 pfIssued++; 164 assert(pkt != NULL); 165 DPRINTF(HWPrefetch, "returning 0x%x\n", pkt->getAddr()); 166 return pkt; 167} 168 169 170Tick 171BasePrefetcher::notify(PacketPtr &pkt, Tick time) 172{ 173 if (!pkt->req->isUncacheable() && !(pkt->req->isInstFetch() && onlyData)) { 174 // Calculate the blk address 175 Addr blk_addr = pkt->getAddr() & ~(Addr)(blkSize-1); 176 177 // Check if miss is in pfq, if so remove it 178 std::list<PacketPtr>::iterator iter = inPrefetch(blk_addr); 179 if (iter != pf.end()) { 180 DPRINTF(HWPrefetch, "Saw a miss to a queued prefetch addr: " 181 "0x%x, removing it\n", blk_addr); 182 pfRemovedMSHR++; 183 delete (*iter)->req; 184 delete (*iter); 185 pf.erase(iter); 186 if (pf.empty()) 187 cache->deassertMemSideBusRequest(BaseCache::Request_PF); 188 } 189 190 // Remove anything in queue with delay older than time 191 // since everything is inserted in time order, start from end 192 // and work until pf.empty() or time is earlier 193 // This is done to emulate Aborting the previous work on a new miss 194 // Needed for serial calculators like GHB 195 if (serialSquash) { 196 iter = pf.end(); 197 iter--; 198 while (!pf.empty() && ((*iter)->time >= time)) { 199 pfSquashed++; 200 DPRINTF(HWPrefetch, "Squashing old prefetch addr: 0x%x\n", 201 (*iter)->getAddr()); 202 delete (*iter)->req; 203 delete (*iter); 204 pf.erase(iter); 205 iter--; 206 } 207 if (pf.empty()) 208 cache->deassertMemSideBusRequest(BaseCache::Request_PF); 209 } 210 211 212 std::list<Addr> addresses; 213 std::list<Tick> delays; 214 calculatePrefetch(pkt, addresses, delays); 215 216 std::list<Addr>::iterator addrIter = addresses.begin(); 217 std::list<Tick>::iterator delayIter = delays.begin(); 218 for (; addrIter != addresses.end(); ++addrIter, ++delayIter) { 219 Addr addr = *addrIter; 220 221 pfIdentified++; 222 223 DPRINTF(HWPrefetch, "Found a pf candidate addr: 0x%x, " 224 "inserting into prefetch queue with delay %d time %d\n", 225 addr, *delayIter, time); 226 227 // Check if it is already in the cache 228 if (cacheCheckPush && cache->inCache(addr)) { 229 DPRINTF(HWPrefetch, "Prefetch addr already in cache\n"); 230 continue; 231 } 232 233 // Check if it is already in the miss_queue 234 if (cache->inMissQueue(addr)) { 235 DPRINTF(HWPrefetch, "Prefetch addr already in miss queue\n"); 236 continue; 237 } 238 239 // Check if it is already in the pf buffer 240 if (inPrefetch(addr) != pf.end()) { 241 pfBufferHit++; 242 DPRINTF(HWPrefetch, "Prefetch addr already in pf buffer\n"); 243 continue; 244 } 245 246 // create a prefetch memreq 247 Request *prefetchReq = new Request(*addrIter, blkSize, 0); 248 PacketPtr prefetch = 249 new Packet(prefetchReq, MemCmd::HardPFReq, Packet::Broadcast); 250 prefetch->allocate(); 251 prefetch->req->setThreadContext(pkt->req->contextId(), 252 pkt->req->threadId()); 253 254 prefetch->time = time + (*delayIter); // @todo ADD LATENCY HERE 255 256 // We just remove the head if we are full 257 if (pf.size() == size) { 258 pfRemovedFull++; 259 PacketPtr old_pkt = *pf.begin(); 260 DPRINTF(HWPrefetch, "Prefetch queue full, " 261 "removing oldest 0x%x\n", old_pkt->getAddr()); 262 delete old_pkt->req; 263 delete old_pkt; 264 pf.pop_front(); 265 } 266 267 pf.push_back(prefetch); 268 } 269 } 270 271 return pf.empty() ? 0 : pf.front()->time; 272} 273 274std::list<PacketPtr>::iterator 275BasePrefetcher::inPrefetch(Addr address) 276{ 277 // Guaranteed to only be one match, we always check before inserting 278 std::list<PacketPtr>::iterator iter; 279 for (iter = pf.begin(); iter != pf.end(); iter++) { 280 if (((*iter)->getAddr() & ~(Addr)(blkSize-1)) == address) { 281 return iter; 282 } 283 } 284 return pf.end(); 285} 286 287bool 288BasePrefetcher::samePage(Addr a, Addr b) 289{ 290 return roundDown(a, TheISA::VMPageSize) == roundDown(b, TheISA::VMPageSize); 291} 292