1/* |
2 * Copyright (c) 2013-2017,2019 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 --- 33 unchanged lines hidden (view full) --- 44 45#include "mem/snoop_filter.hh" 46 47#include "base/logging.hh" 48#include "base/trace.hh" 49#include "debug/SnoopFilter.hh" 50#include "sim/system.hh" 51 |
52const int SnoopFilter::SNOOP_MASK_SIZE; 53 |
54void 55SnoopFilter::eraseIfNullEntry(SnoopFilterCache::iterator& sf_it) 56{ 57 SnoopItem& sf_item = sf_it->second; |
58 if ((sf_item.requested | sf_item.holder).none()) { |
59 cachedLocations.erase(sf_it); 60 DPRINTF(SnoopFilter, "%s: Removed SF entry.\n", 61 __func__); 62 } 63} 64 65std::pair<SnoopFilter::SnoopList, Cycles> 66SnoopFilter::lookupRequest(const Packet* cpkt, const SlavePort& slave_port) --- 26 unchanged lines hidden (view full) --- 93 94 // Store unmodified value of snoop filter item in temp storage in 95 // case we need to revert because of a send retry in 96 // updateRequest. 97 retryItem = sf_item; 98 99 totRequests++; 100 if (is_hit) { |
101 if (interested.count() == 1) |
102 hitSingleRequests++; 103 else 104 hitMultiRequests++; 105 } 106 107 DPRINTF(SnoopFilter, "%s: SF value %x.%x\n", 108 __func__, sf_item.requested, sf_item.holder); 109 110 // If we are not allocating, we are done 111 if (!allocate) 112 return snoopSelected(maskToPortList(interested & ~req_port), 113 lookupLatency); 114 115 if (cpkt->needsResponse()) { 116 if (!cpkt->cacheResponding()) { 117 // Max one request per address per port |
118 panic_if((sf_item.requested & req_port).any(), 119 "double request :( SF value %x.%x\n", 120 sf_item.requested, sf_item.holder); |
121 122 // Mark in-flight requests to distinguish later on 123 sf_item.requested |= req_port; 124 DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n", 125 __func__, sf_item.requested, sf_item.holder); 126 } else { 127 // NOTE: The memInhibit might have been asserted by a cache closer 128 // to the CPU, already -> the response will not be seen by this 129 // filter -> we do not need to keep the in-flight request, but make 130 // sure that we know that that cluster has a copy |
131 panic_if((sf_item.holder & req_port).none(), 132 "Need to hold the value!"); |
133 DPRINTF(SnoopFilter, 134 "%s: not marking request. SF value %x.%x\n", 135 __func__, sf_item.requested, sf_item.holder); 136 } 137 } else { // if (!cpkt->needsResponse()) 138 assert(cpkt->isEviction()); 139 // make sure that the sender actually had the line |
140 panic_if((sf_item.holder & req_port).none(), "requester %x is not a " \ |
141 "holder :( SF value %x.%x\n", req_port, 142 sf_item.requested, sf_item.holder); 143 // CleanEvicts and Writebacks -> the sender and all caches above 144 // it may not have the line anymore. 145 if (!cpkt->isBlockCached()) { 146 sf_item.holder &= ~req_port; 147 DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n", 148 __func__, sf_item.requested, sf_item.holder); --- 55 unchanged lines hidden (view full) --- 204 SnoopItem& sf_item = sf_it->second; 205 206 DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n", 207 __func__, sf_item.requested, sf_item.holder); 208 209 SnoopMask interested = (sf_item.holder | sf_item.requested); 210 211 totSnoops++; |
212 213 if (interested.count() == 1) |
214 hitSingleSnoops++; 215 else 216 hitMultiSnoops++; 217 218 // ReadEx and Writes require both invalidation and exlusivity, while reads 219 // require neither. Writebacks on the other hand require exclusivity but 220 // not the invalidation. Previously Writebacks did not generate upward 221 // snoops so this was never an issue. Now that Writebacks generate snoops 222 // we need a special case for Writebacks. Additionally cache maintenance 223 // operations can generate snoops as they clean and/or invalidate all 224 // caches down to the specified point of reference. 225 assert(cpkt->isWriteback() || cpkt->req->isUncacheable() || 226 (cpkt->isInvalidate() == cpkt->needsWritable()) || 227 cpkt->req->isCacheMaintenance()); |
228 if (cpkt->isInvalidate() && sf_item.requested.none()) { |
229 // Early clear of the holder, if no other request is currently going on 230 // @todo: This should possibly be updated even though we do not filter 231 // upward snoops 232 sf_item.holder = 0; 233 } 234 235 eraseIfNullEntry(sf_it); 236 DPRINTF(SnoopFilter, "%s: new SF value %x.%x interest: %x \n", --- 27 unchanged lines hidden (view full) --- 264 SnoopMask rsp_mask = portToMask(rsp_port); 265 SnoopMask req_mask = portToMask(req_port); 266 SnoopItem& sf_item = cachedLocations[line_addr]; 267 268 DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n", 269 __func__, sf_item.requested, sf_item.holder); 270 271 // The source should have the line |
272 panic_if((sf_item.holder & rsp_mask).none(), 273 "SF value %x.%x does not have the line\n", 274 sf_item.requested, sf_item.holder); |
275 276 // The destination should have had a request in |
277 panic_if((sf_item.requested & req_mask).none(), "SF value %x.%x missing "\ |
278 "the original request\n", sf_item.requested, sf_item.holder); 279 280 // If the snoop response has no sharers the line is passed in 281 // Modified state, and we know that there are no other copies, or 282 // they will all be invalidated imminently 283 if (!cpkt->hasSharers()) { 284 DPRINTF(SnoopFilter, 285 "%s: dropping %x because non-shared snoop " 286 "response SF val: %x.%x\n", __func__, rsp_mask, 287 sf_item.requested, sf_item.holder); 288 sf_item.holder = 0; 289 } 290 assert(!cpkt->isWriteback()); 291 // @todo Deal with invalidating responses 292 sf_item.holder |= req_mask; 293 sf_item.requested &= ~req_mask; |
294 assert((sf_item.requested | sf_item.holder).any()); |
295 DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n", 296 __func__, sf_item.requested, sf_item.holder); 297} 298 299void 300SnoopFilter::updateSnoopForward(const Packet* cpkt, 301 const SlavePort& rsp_port, const MasterPort& req_port) 302{ --- 55 unchanged lines hidden (view full) --- 358 359 SnoopMask slave_mask = portToMask(slave_port); 360 SnoopItem& sf_item = sf_it->second; 361 362 DPRINTF(SnoopFilter, "%s: old SF value %x.%x\n", 363 __func__, sf_item.requested, sf_item.holder); 364 365 // Make sure we have seen the actual request, too |
366 panic_if((sf_item.requested & slave_mask).none(), 367 "SF value %x.%x missing request bit\n", 368 sf_item.requested, sf_item.holder); |
369 370 sf_item.requested &= ~slave_mask; 371 // Update the residency of the cache line. 372 373 if (cpkt->req->isCacheMaintenance()) { 374 // A cache clean response does not carry any data so it 375 // shouldn't change the holders, unless it is invalidating. 376 if (cpkt->isInvalidate()) { 377 sf_item.holder &= ~slave_mask; 378 } 379 eraseIfNullEntry(sf_it); 380 } else { 381 // Any other response implies that a cache above will have the 382 // block. 383 sf_item.holder |= slave_mask; |
384 assert((sf_item.holder | sf_item.requested).any()); |
385 } 386 DPRINTF(SnoopFilter, "%s: new SF value %x.%x\n", 387 __func__, sf_item.requested, sf_item.holder); 388} 389 390void 391SnoopFilter::regStats() 392{ --- 36 unchanged lines hidden --- |