1/* 2 * Copyright (c) 2013-2015 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 --- 34 unchanged lines hidden (view full) --- 43 */ 44 45#include "base/misc.hh" 46#include "base/trace.hh" 47#include "debug/SnoopFilter.hh" 48#include "mem/snoop_filter.hh" 49#include "sim/system.hh" 50 |
51void 52SnoopFilter::eraseIfNullEntry(SnoopFilterCache::iterator& sf_it) 53{ 54 SnoopItem& sf_item = sf_it->second; 55 if (!(sf_item.requested | sf_item.holder)) { 56 cachedLocations.erase(sf_it); 57 DPRINTF(SnoopFilter, "%s: Removed SF entry.\n", 58 __func__); 59 } 60} 61 |
62std::pair<SnoopFilter::SnoopList, Cycles> 63SnoopFilter::lookupRequest(const Packet* cpkt, const SlavePort& slave_port) 64{ 65 DPRINTF(SnoopFilter, "%s: packet src %s addr 0x%x cmd %s\n", 66 __func__, slave_port.name(), cpkt->getAddr(), cpkt->cmdString()); 67 68 // Ultimately we should check if the packet came from an 69 // allocating source, not just if the port is snooping --- 8 unchanged lines hidden (view full) --- 78 // portlist. 79 if (!is_hit && !allocate) 80 return snoopDown(lookupLatency); 81 82 // Create a new element through operator[] and modify in-place 83 SnoopItem& sf_item = is_hit ? sf_it->second : cachedLocations[line_addr]; 84 SnoopMask interested = sf_item.holder | sf_item.requested; 85 |
86 // Store unmodified value of snoop filter item in temp storage in 87 // case we need to revert because of a send retry in 88 // updateRequest. 89 retryItem = sf_item; 90 |
91 totRequests++; 92 if (is_hit) { 93 // Single bit set -> value is a power of two 94 if (isPow2(interested)) 95 hitSingleRequests++; 96 else 97 hitMultiRequests++; 98 } 99 100 DPRINTF(SnoopFilter, "%s: SF value %x.%x\n", 101 __func__, sf_item.requested, sf_item.holder); 102 |
103 // If we are not allocating, we are done 104 if (!allocate) 105 return snoopSelected(maskToPortList(interested & ~req_port), 106 lookupLatency); 107 108 if (cpkt->needsResponse()) { |
109 if (!cpkt->memInhibitAsserted()) { 110 // Max one request per address per port |
111 panic_if(sf_item.requested & req_port, "double request :( " \ |
112 "SF value %x.%x\n", sf_item.requested, sf_item.holder); 113 114 // Mark in-flight requests to distinguish later on 115 sf_item.requested |= req_port; |
116 DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n", 117 __func__, sf_item.requested, sf_item.holder); |
118 } else { 119 // NOTE: The memInhibit might have been asserted by a cache closer 120 // to the CPU, already -> the response will not be seen by this 121 // filter -> we do not need to keep the in-flight request, but make 122 // sure that we know that that cluster has a copy 123 panic_if(!(sf_item.holder & req_port), "Need to hold the value!"); |
124 DPRINTF(SnoopFilter, 125 "%s: not marking request. SF value %x.%x\n", |
126 __func__, sf_item.requested, sf_item.holder); 127 } |
128 } else { // if (!cpkt->needsResponse()) 129 assert(cpkt->evictingBlock()); 130 // make sure that the sender actually had the line 131 panic_if(!(sf_item.holder & req_port), "requester %x is not a " \ 132 "holder :( SF value %x.%x\n", req_port, 133 sf_item.requested, sf_item.holder); 134 // CleanEvicts and Writebacks -> the sender and all caches above 135 // it may not have the line anymore. 136 if (!cpkt->isBlockCached()) { 137 sf_item.holder &= ~req_port; 138 DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n", 139 __func__, sf_item.requested, sf_item.holder); 140 } |
141 } |
142 |
143 return snoopSelected(maskToPortList(interested & ~req_port), lookupLatency); 144} 145 146void 147SnoopFilter::updateRequest(const Packet* cpkt, const SlavePort& slave_port, 148 bool will_retry) 149{ 150 DPRINTF(SnoopFilter, "%s: packet src %s addr 0x%x cmd %s\n", 151 __func__, slave_port.name(), cpkt->getAddr(), cpkt->cmdString()); 152 153 // Ultimately we should check if the packet came from an 154 // allocating source, not just if the port is snooping 155 bool allocate = !cpkt->req->isUncacheable() && slave_port.isSnooping(); 156 if (!allocate) 157 return; 158 159 Addr line_addr = cpkt->getBlockAddr(linesize); |
160 auto sf_it = cachedLocations.find(line_addr); 161 assert(sf_it != cachedLocations.end()); |
162 if (will_retry) { |
163 // Undo any changes made in lookupRequest to the snoop filter 164 // entry if the request will come again. retryItem holds 165 // the previous value of the snoopfilter entry. 166 sf_it->second = retryItem; |
167 |
168 DPRINTF(SnoopFilter, "%s: restored SF value %x.%x\n", 169 __func__, retryItem.requested, retryItem.holder); |
170 } |
171 172 eraseIfNullEntry(sf_it); |
173} 174 175std::pair<SnoopFilter::SnoopList, Cycles> 176SnoopFilter::lookupSnoop(const Packet* cpkt) 177{ 178 DPRINTF(SnoopFilter, "%s: packet addr 0x%x cmd %s\n", 179 __func__, cpkt->getAddr(), cpkt->cmdString()); 180 181 assert(cpkt->isRequest()); 182 183 // Broadcast / filter upward snoops 184 const bool filter_upward = true; // @todo: Make configurable 185 186 if (!filter_upward) 187 return snoopAll(lookupLatency); 188 189 Addr line_addr = cpkt->getBlockAddr(linesize); 190 auto sf_it = cachedLocations.find(line_addr); 191 bool is_hit = (sf_it != cachedLocations.end()); |
192 |
193 // If the snoop filter has no entry and its an uncacheable 194 // request, do not create a new snoop filter entry, simply return 195 // a NULL portlist. 196 if (!is_hit && cpkt->req->isUncacheable()) 197 return snoopDown(lookupLatency); 198 199 // If no hit in snoop filter create a new element and update iterator 200 if (!is_hit) 201 sf_it = cachedLocations.emplace(line_addr, SnoopItem()).first; 202 SnoopItem& sf_item = sf_it->second; 203 |
204 DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n", 205 __func__, sf_item.requested, sf_item.holder); 206 207 SnoopMask interested = (sf_item.holder | sf_item.requested); 208 209 totSnoops++; 210 if (is_hit) { 211 // Single bit set -> value is a power of two 212 if (isPow2(interested)) 213 hitSingleSnoops++; 214 else 215 hitMultiSnoops++; 216 } 217 // ReadEx and Writes require both invalidation and exlusivity, while reads 218 // require neither. Writebacks on the other hand require exclusivity but 219 // not the invalidation. Previously Writebacks did not generate upward 220 // snoops so this was never an aissue. Now that Writebacks generate snoops 221 // we need to special case for Writebacks. |
222 assert(cpkt->cmd == MemCmd::Writeback || cpkt->req->isUncacheable() || |
223 (cpkt->isInvalidate() == cpkt->needsExclusive())); 224 if (cpkt->isInvalidate() && !sf_item.requested) { 225 // Early clear of the holder, if no other request is currently going on 226 // @todo: This should possibly be updated even though we do not filter 227 // upward snoops 228 sf_item.holder = 0; 229 } 230 |
231 eraseIfNullEntry(sf_it); |
232 DPRINTF(SnoopFilter, "%s: new SF value %x.%x interest: %x \n", 233 __func__, sf_item.requested, sf_item.holder, interested); 234 235 return snoopSelected(maskToPortList(interested), lookupLatency); 236} 237 238void 239SnoopFilter::updateSnoopResponse(const Packet* cpkt, --- 40 unchanged lines hidden (view full) --- 280 // The snoop filter does not see any ACKs from non-responding sharers 281 // that have been invalidated :( So below assert would be nice, but.. 282 //assert(sf_item.holder == 0); 283 sf_item.holder = 0; 284 } 285 assert(cpkt->cmd != MemCmd::Writeback); 286 sf_item.holder |= req_mask; 287 sf_item.requested &= ~req_mask; |
288 assert(sf_item.requested | sf_item.holder); |
289 DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n", 290 __func__, sf_item.requested, sf_item.holder); 291} 292 293void 294SnoopFilter::updateSnoopForward(const Packet* cpkt, 295 const SlavePort& rsp_port, const MasterPort& req_port) 296{ 297 DPRINTF(SnoopFilter, "%s: packet rsp %s req %s addr 0x%x cmd %s\n", 298 __func__, rsp_port.name(), req_port.name(), cpkt->getAddr(), 299 cpkt->cmdString()); 300 301 Addr line_addr = cpkt->getBlockAddr(linesize); |
302 auto sf_it = cachedLocations.find(line_addr); 303 if (sf_it == cachedLocations.end()) 304 sf_it = cachedLocations.emplace(line_addr, SnoopItem()).first; 305 SnoopItem& sf_item = sf_it->second; |
306 SnoopMask rsp_mask M5_VAR_USED = portToMask(rsp_port); 307 308 assert(cpkt->isResponse()); 309 assert(cpkt->memInhibitAsserted()); 310 311 DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n", 312 __func__, sf_item.requested, sf_item.holder); 313 314 // Remote (to this snoop filter) snoops update the filter already when they 315 // arrive from below, because we may not see any response. 316 if (cpkt->needsExclusive()) { 317 // If the request to this snoop response hit an in-flight transaction, 318 // the holder was not reset -> no assertion & do that here, now! 319 //assert(sf_item.holder == 0); 320 sf_item.holder = 0; 321 } 322 DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n", 323 __func__, sf_item.requested, sf_item.holder); |
324 eraseIfNullEntry(sf_it); |
325} 326 327void 328SnoopFilter::updateResponse(const Packet* cpkt, const SlavePort& slave_port) 329{ 330 DPRINTF(SnoopFilter, "%s: packet src %s addr 0x%x cmd %s\n", 331 __func__, slave_port.name(), cpkt->getAddr(), cpkt->cmdString()); 332 --- 11 unchanged lines hidden (view full) --- 344 345 DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n", 346 __func__, sf_item.requested, sf_item.holder); 347 348 // Make sure we have seen the actual request, too 349 panic_if(!(sf_item.requested & slave_mask), "SF value %x.%x missing "\ 350 "request bit\n", sf_item.requested, sf_item.holder); 351 |
352 // Update the residency of the cache line. Here we assume that the 353 // line has been zapped in all caches that are not the responder. 354 if (cpkt->needsExclusive() || !cpkt->sharedAsserted()) |
355 sf_item.holder = 0; 356 sf_item.holder |= slave_mask; 357 sf_item.requested &= ~slave_mask; |
358 assert(sf_item.holder | sf_item.requested); |
359 DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n", 360 __func__, sf_item.requested, sf_item.holder); 361} 362 363void 364SnoopFilter::regStats() 365{ 366 totRequests --- 33 unchanged lines hidden --- |