1/*
2 * Copyright (c) 2010-2014 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

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51
52using namespace std;
53
54DRAMCtrl::DRAMCtrl(const DRAMCtrlParams* p) :
55 AbstractMemory(p),
56 port(name() + ".port", *this),
57 retryRdReq(false), retryWrReq(false),
58 rowHitFlag(false), busState(READ),
59 respondEvent(this),
60 refreshEvent(this), nextReqEvent(this), drainManager(NULL),
61 deviceBusWidth(p->device_bus_width), burstLength(p->burst_length),
62 deviceRowBufferSize(p->device_rowbuffer_size),
63 devicesPerRank(p->devices_per_rank),
64 burstSize((devicesPerRank * burstLength * deviceBusWidth) / 8),
65 rowBufferSize(devicesPerRank * deviceRowBufferSize),
66 columnsPerRowBuffer(rowBufferSize / burstSize),
67 ranksPerChannel(p->ranks_per_channel),
68 banksPerRank(p->banks_per_rank), channels(p->channels), rowsPerBank(0),

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76 tRCD(p->tRCD), tCL(p->tCL), tRP(p->tRP), tRAS(p->tRAS),
77 tRFC(p->tRFC), tREFI(p->tREFI), tRRD(p->tRRD),
78 tXAW(p->tXAW), activationLimit(p->activation_limit),
79 memSchedPolicy(p->mem_sched_policy), addrMapping(p->addr_mapping),
80 pageMgmt(p->page_policy),
81 maxAccessesPerRow(p->max_accesses_per_row),
82 frontendLatency(p->static_frontend_latency),
83 backendLatency(p->static_backend_latency),
84 busBusyUntil(0), prevArrival(0),
85 nextReqTime(0), startTickPrechargeAll(0), numBanksActive(0)
86{
87 // create the bank states based on the dimensions of the ranks and
88 // banks
89 banks.resize(ranksPerChannel);
90 actTicks.resize(ranksPerChannel);
91 for (size_t c = 0; c < ranksPerChannel; ++c) {
92 banks[c].resize(banksPerRank);
93 actTicks[c].resize(activationLimit, 0);

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126 "address map\n", name());
127 }
128 } else if (addrMapping == Enums::RoCoRaBaCh) {
129 if (system()->cacheLineSize() != range.granularity())
130 fatal("Interleaving of %s doesn't match RoCoRaBaCh "
131 "address map\n", name());
132 }
133 }
134}
135
136void
137DRAMCtrl::init()
138{
139 if (!port.isConnected()) {
140 fatal("DRAMCtrl %s is unconnected!\n", name());
141 } else {
142 port.sendRangeChange();
143 }
144}
145
146void
147DRAMCtrl::startup()
148{
149 // update the start tick for the precharge accounting to the
150 // current tick
151 startTickPrechargeAll = curTick();
152
153 // shift the bus busy time sufficiently far ahead that we never
154 // have to worry about negative values when computing the time for
155 // the next request, this will add an insignificant bubble at the
156 // start of simulation
157 busBusyUntil = curTick() + tRP + tRCD + tCL;
158
159 // print the configuration of the controller
160 printParams();
161
162 // kick off the refresh
163 schedule(refreshEvent, curTick() + tREFI);
164}
165
166Tick
167DRAMCtrl::recvAtomic(PacketPtr pkt)
168{
169 DPRINTF(DRAM, "recvAtomic: %s 0x%x\n", pkt->cmdString(), pkt->getAddr());
170
171 // do the actual memory access and turn the packet into a response

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830 // then add cas latency.
831 Tick freeTime = std::max(bank.tRASDoneAt, bank.freeAt);
832
833 if (freeTime > inTime)
834 accLat += freeTime - inTime;
835
836 // If the there is no open row (open adaptive), then there
837 // is no precharge delay, otherwise go with tRP
838 Tick precharge_delay = bank.openRow == -1 ? 0 : tRP;
839
840 //The bank is free, and you may be able to activate
841 potentialActTick = inTime + accLat + precharge_delay;
842 if (potentialActTick < bank.actAllowedAt)
843 accLat += bank.actAllowedAt - potentialActTick;
844
845 accLat += precharge_delay + tRCD + tCL;
846 bankLat += precharge_delay + tRCD + tCL;

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865
866 DPRINTF(DRAM, "Returning < %lld, %lld > from estimateLatency()\n",
867 bankLat, accLat);
868
869 return make_pair(bankLat, accLat);
870}
871
872void
873DRAMCtrl::recordActivate(Tick act_tick, uint8_t rank, uint8_t bank)
874{
875 assert(0 <= rank && rank < ranksPerChannel);
876 assert(actTicks[rank].size() == activationLimit);
877
878 DPRINTF(DRAM, "Activate at tick %d\n", act_tick);
879
880 // Tracking accesses after all banks are precharged.
881 // startTickPrechargeAll: is the tick when all the banks were again
882 // precharged. The difference between act_tick and startTickPrechargeAll
883 // gives the time for which DRAM doesn't get any accesses after refreshing
884 // or after a page is closed in closed-page or open-adaptive-page policy.
885 if ((numBanksActive == 0) && (act_tick > startTickPrechargeAll)) {
886 prechargeAllTime += act_tick - startTickPrechargeAll;
887 }
888
889 // No need to update number of active banks for closed-page policy as only 1
890 // bank will be activated at any given point, which will be instatntly
891 // precharged
892 if (pageMgmt == Enums::open || pageMgmt == Enums::open_adaptive ||
893 pageMgmt == Enums::close_adaptive)
894 ++numBanksActive;
895
896 // start by enforcing tRRD
897 for(int i = 0; i < banksPerRank; i++) {
898 // next activate must not happen before tRRD
899 banks[rank][i].actAllowedAt = act_tick + tRRD;
900 }
901 // tRC should be added to activation tick of the bank currently accessed,
902 // where tRC = tRAS + tRP, this is just for a check as actAllowedAt for same
903 // bank is already captured by bank.freeAt and bank.tRASDoneAt

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931 "than %d\n", activationLimit, actTicks[rank].back() + tXAW);
932 for(int j = 0; j < banksPerRank; j++)
933 // next activate must not happen before end of window
934 banks[rank][j].actAllowedAt = actTicks[rank].back() + tXAW;
935 }
936}
937
938void
939DRAMCtrl::doDRAMAccess(DRAMPacket* dram_pkt)
940{
941
942 DPRINTF(DRAM, "Timing access to addr %lld, rank/bank/row %d %d %d\n",
943 dram_pkt->addr, dram_pkt->rank, dram_pkt->bank, dram_pkt->row);
944
945 // estimate the bank and access latency
946 pair<Tick, Tick> lat = estimateLatency(dram_pkt, curTick());

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956 Tick addDelay = (curTick() + accessLat < busBusyUntil) ?
957 busBusyUntil - (curTick() + accessLat) : 0;
958
959 Bank& bank = dram_pkt->bankRef;
960
961 // Update bank state
962 if (pageMgmt == Enums::open || pageMgmt == Enums::open_adaptive ||
963 pageMgmt == Enums::close_adaptive) {
964 bank.freeAt = curTick() + addDelay + accessLat;
965
966 // If you activated a new row do to this access, the next access
967 // will have to respect tRAS for this bank.
968 if (!rowHitFlag) {
969 // any waiting for banks account for in freeAt
970 actTick = bank.freeAt - tCL - tRCD;
971 bank.tRASDoneAt = actTick + tRAS;
972 recordActivate(actTick, dram_pkt->rank, dram_pkt->bank);
973
974 // if we closed an open row as a result of this access,
975 // then sample the number of bytes accessed before
976 // resetting it
977 if (bank.openRow != -1)
978 bytesPerActivate.sample(bank.bytesAccessed);
979
980 // update the open row
981 bank.openRow = dram_pkt->row;
982
983 // start counting anew, this covers both the case when we
984 // auto-precharged, and when this access is forced to
985 // precharge
986 bank.bytesAccessed = 0;
987 bank.rowAccesses = 0;
988 }
989
990 // increment the bytes accessed and the accesses per row
991 bank.bytesAccessed += burstSize;
992 ++bank.rowAccesses;
993
994 // if we reached the max, then issue with an auto-precharge
995 bool auto_precharge = bank.rowAccesses == maxAccessesPerRow;

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1037 // 2) close_adaptive policy and we have not got any more hits
1038 auto_precharge = !got_more_hits &&
1039 (got_bank_conflict || pageMgmt == Enums::close_adaptive);
1040 }
1041
1042 // if this access should use auto-precharge, then we are
1043 // closing the row
1044 if (auto_precharge) {
1045 bank.openRow = -1;
1046 bank.freeAt = std::max(bank.freeAt, bank.tRASDoneAt) + tRP;
1047 --numBanksActive;
1048 if (numBanksActive == 0) {
1049 startTickPrechargeAll = std::max(startTickPrechargeAll,
1050 bank.freeAt);
1051 DPRINTF(DRAM, "All banks precharged at tick: %ld\n",
1052 startTickPrechargeAll);
1053 }
1054
1055 // sample the bytes per activate here since we are closing
1056 // the page
1057 bytesPerActivate.sample(bank.bytesAccessed);
1058
1059 DPRINTF(DRAM, "Auto-precharged bank: %d\n", dram_pkt->bankId);
1060 }
1061
1062 DPRINTF(DRAM, "doDRAMAccess::bank.freeAt is %lld\n", bank.freeAt);
1063 } else if (pageMgmt == Enums::close) {
1064 actTick = curTick() + addDelay + accessLat - tRCD - tCL;
1065 recordActivate(actTick, dram_pkt->rank, dram_pkt->bank);
1066
1067 // If the DRAM has a very quick tRAS, bank can be made free
1068 // after consecutive tCL,tRCD,tRP times. In general, however,
1069 // an additional wait is required to respect tRAS.
1070 bank.freeAt = std::max(actTick + tRAS + tRP,
1071 actTick + tRCD + tCL + tRP);
1072 DPRINTF(DRAM, "doDRAMAccess::bank.freeAt is %lld\n", bank.freeAt);
1073 bytesPerActivate.sample(burstSize);
1074 startTickPrechargeAll = std::max(startTickPrechargeAll, bank.freeAt);
1075 } else
1076 panic("No page management policy chosen\n");
1077
1078 // Update request parameters
1079 dram_pkt->readyTime = curTick() + addDelay + accessLat + tBURST;
1080
1081
1082 DPRINTF(DRAM, "Req %lld: curtick is %lld accessLat is %d " \

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1182 "waiting\n", writesThisTime, writeQueue.size());
1183
1184 wrPerTurnAround.sample(writesThisTime);
1185 writesThisTime = 0;
1186
1187 busState = READ;
1188 }
1189
1190 // when we get here it is either a read or a write
1191 if (busState == READ) {
1192
1193 // track if we should switch or not
1194 bool switch_to_writes = false;
1195
1196 if (readQueue.empty()) {
1197 // In the case there is no read request to go next,

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1293 // cause a nextReqEvent to be scheduled before we do so as part of
1294 // the next request processing
1295 if (retryWrReq && writeQueue.size() < writeBufferSize) {
1296 retryWrReq = false;
1297 port.sendRetry();
1298 }
1299}
1300
1301Tick
1302DRAMCtrl::maxBankFreeAt() const
1303{
1304 Tick banksFree = 0;
1305
1306 for(int i = 0; i < ranksPerChannel; i++)
1307 for(int j = 0; j < banksPerRank; j++)
1308 banksFree = std::max(banks[i][j].freeAt, banksFree);
1309
1310 return banksFree;
1311}
1312
1313uint64_t
1314DRAMCtrl::minBankFreeAt(const deque<DRAMPacket*>& queue) const
1315{
1316 uint64_t bank_mask = 0;
1317 Tick freeAt = MaxTick;
1318
1319 // detemrine if we have queued transactions targetting the
1320 // bank in question

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1340 }
1341 }
1342 return bank_mask;
1343}
1344
1345void
1346DRAMCtrl::processRefreshEvent()
1347{
1348 DPRINTF(DRAM, "Refreshing at tick %ld\n", curTick());
1349
1350 Tick banksFree = std::max(curTick(), maxBankFreeAt()) + tRFC;
1351
1352 for(int i = 0; i < ranksPerChannel; i++)
1353 for(int j = 0; j < banksPerRank; j++) {
1354 banks[i][j].freeAt = banksFree;
1355 banks[i][j].openRow = -1;
1356 }
1357
1358 // updating startTickPrechargeAll, isprechargeAll
1359 numBanksActive = 0;
1360 startTickPrechargeAll = banksFree;
1361
1362 schedule(refreshEvent, curTick() + tREFI);
1363}
1364
1365void
1366DRAMCtrl::regStats()
1367{
1368 using namespace Stats;
1369
1370 AbstractMemory::regStats();

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