/* * Copyright (c) 2010-2014 ARM Limited * All rights reserved * * The license below extends only to copyright in the software and shall * not be construed as granting a license to any other intellectual * property including but not limited to intellectual property relating * to a hardware implementation of the functionality of the software * licensed hereunder. You may use the software subject to the license * terms below provided that you ensure that this notice is replicated * unmodified and in its entirety in all distributions of the software, * modified or unmodified, in source code or in binary form. * * Copyright (c) 2013 Amin Farmahini-Farahani * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer; * redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution; * neither the name of the copyright holders nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * Authors: Andreas Hansson * Ani Udipi * Neha Agarwal */ #include "base/bitfield.hh" #include "base/trace.hh" #include "debug/DRAM.hh" #include "debug/DRAMState.hh" #include "debug/Drain.hh" #include "mem/dram_ctrl.hh" #include "sim/system.hh" using namespace std; DRAMCtrl::DRAMCtrl(const DRAMCtrlParams* p) : AbstractMemory(p), port(name() + ".port", *this), retryRdReq(false), retryWrReq(false), rowHitFlag(false), busState(READ), nextReqEvent(this), respondEvent(this), activateEvent(this), prechargeEvent(this), refreshEvent(this), powerEvent(this), drainManager(NULL), deviceBusWidth(p->device_bus_width), burstLength(p->burst_length), deviceRowBufferSize(p->device_rowbuffer_size), devicesPerRank(p->devices_per_rank), burstSize((devicesPerRank * burstLength * deviceBusWidth) / 8), rowBufferSize(devicesPerRank * deviceRowBufferSize), columnsPerRowBuffer(rowBufferSize / burstSize), ranksPerChannel(p->ranks_per_channel), banksPerRank(p->banks_per_rank), channels(p->channels), rowsPerBank(0), readBufferSize(p->read_buffer_size), writeBufferSize(p->write_buffer_size), writeHighThreshold(writeBufferSize * p->write_high_thresh_perc / 100.0), writeLowThreshold(writeBufferSize * p->write_low_thresh_perc / 100.0), minWritesPerSwitch(p->min_writes_per_switch), writesThisTime(0), readsThisTime(0), tWTR(p->tWTR), tRTW(p->tRTW), tBURST(p->tBURST), tRCD(p->tRCD), tCL(p->tCL), tRP(p->tRP), tRAS(p->tRAS), tRFC(p->tRFC), tREFI(p->tREFI), tRRD(p->tRRD), tXAW(p->tXAW), activationLimit(p->activation_limit), memSchedPolicy(p->mem_sched_policy), addrMapping(p->addr_mapping), pageMgmt(p->page_policy), maxAccessesPerRow(p->max_accesses_per_row), frontendLatency(p->static_frontend_latency), backendLatency(p->static_backend_latency), busBusyUntil(0), refreshDueAt(0), refreshState(REF_IDLE), pwrStateTrans(PWR_IDLE), pwrState(PWR_IDLE), prevArrival(0), nextReqTime(0), pwrStateTick(0), numBanksActive(0) { // create the bank states based on the dimensions of the ranks and // banks banks.resize(ranksPerChannel); actTicks.resize(ranksPerChannel); for (size_t c = 0; c < ranksPerChannel; ++c) { banks[c].resize(banksPerRank); actTicks[c].resize(activationLimit, 0); } // perform a basic check of the write thresholds if (p->write_low_thresh_perc >= p->write_high_thresh_perc) fatal("Write buffer low threshold %d must be smaller than the " "high threshold %d\n", p->write_low_thresh_perc, p->write_high_thresh_perc); // determine the rows per bank by looking at the total capacity uint64_t capacity = ULL(1) << ceilLog2(AbstractMemory::size()); DPRINTF(DRAM, "Memory capacity %lld (%lld) bytes\n", capacity, AbstractMemory::size()); DPRINTF(DRAM, "Row buffer size %d bytes with %d columns per row buffer\n", rowBufferSize, columnsPerRowBuffer); rowsPerBank = capacity / (rowBufferSize * banksPerRank * ranksPerChannel); if (range.interleaved()) { if (channels != range.stripes()) fatal("%s has %d interleaved address stripes but %d channel(s)\n", name(), range.stripes(), channels); if (addrMapping == Enums::RoRaBaChCo) { if (rowBufferSize != range.granularity()) { fatal("Interleaving of %s doesn't match RoRaBaChCo " "address map\n", name()); } } else if (addrMapping == Enums::RoRaBaCoCh) { if (system()->cacheLineSize() != range.granularity()) { fatal("Interleaving of %s doesn't match RoRaBaCoCh " "address map\n", name()); } } else if (addrMapping == Enums::RoCoRaBaCh) { if (system()->cacheLineSize() != range.granularity()) fatal("Interleaving of %s doesn't match RoCoRaBaCh " "address map\n", name()); } } // some basic sanity checks if (tREFI <= tRP || tREFI <= tRFC) { fatal("tREFI (%d) must be larger than tRP (%d) and tRFC (%d)\n", tREFI, tRP, tRFC); } } void DRAMCtrl::init() { if (!port.isConnected()) { fatal("DRAMCtrl %s is unconnected!\n", name()); } else { port.sendRangeChange(); } } void DRAMCtrl::startup() { // update the start tick for the precharge accounting to the // current tick pwrStateTick = curTick(); // shift the bus busy time sufficiently far ahead that we never // have to worry about negative values when computing the time for // the next request, this will add an insignificant bubble at the // start of simulation busBusyUntil = curTick() + tRP + tRCD + tCL; // print the configuration of the controller printParams(); // kick off the refresh, and give ourselves enough time to // precharge schedule(refreshEvent, curTick() + tREFI - tRP); } Tick DRAMCtrl::recvAtomic(PacketPtr pkt) { DPRINTF(DRAM, "recvAtomic: %s 0x%x\n", pkt->cmdString(), pkt->getAddr()); // do the actual memory access and turn the packet into a response access(pkt); Tick latency = 0; if (!pkt->memInhibitAsserted() && pkt->hasData()) { // this value is not supposed to be accurate, just enough to // keep things going, mimic a closed page latency = tRP + tRCD + tCL; } return latency; } bool DRAMCtrl::readQueueFull(unsigned int neededEntries) const { DPRINTF(DRAM, "Read queue limit %d, current size %d, entries needed %d\n", readBufferSize, readQueue.size() + respQueue.size(), neededEntries); return (readQueue.size() + respQueue.size() + neededEntries) > readBufferSize; } bool DRAMCtrl::writeQueueFull(unsigned int neededEntries) const { DPRINTF(DRAM, "Write queue limit %d, current size %d, entries needed %d\n", writeBufferSize, writeQueue.size(), neededEntries); return (writeQueue.size() + neededEntries) > writeBufferSize; } DRAMCtrl::DRAMPacket* DRAMCtrl::decodeAddr(PacketPtr pkt, Addr dramPktAddr, unsigned size, bool isRead) { // decode the address based on the address mapping scheme, with // Ro, Ra, Co, Ba and Ch denoting row, rank, column, bank and // channel, respectively uint8_t rank; uint8_t bank; uint16_t row; // truncate the address to the access granularity Addr addr = dramPktAddr / burstSize; // we have removed the lowest order address bits that denote the // position within the column if (addrMapping == Enums::RoRaBaChCo) { // the lowest order bits denote the column to ensure that // sequential cache lines occupy the same row addr = addr / columnsPerRowBuffer; // take out the channel part of the address addr = addr / channels; // after the channel bits, get the bank bits to interleave // over the banks bank = addr % banksPerRank; addr = addr / banksPerRank; // after the bank, we get the rank bits which thus interleaves // over the ranks rank = addr % ranksPerChannel; addr = addr / ranksPerChannel; // lastly, get the row bits row = addr % rowsPerBank; addr = addr / rowsPerBank; } else if (addrMapping == Enums::RoRaBaCoCh) { // take out the channel part of the address addr = addr / channels; // next, the column addr = addr / columnsPerRowBuffer; // after the column bits, we get the bank bits to interleave // over the banks bank = addr % banksPerRank; addr = addr / banksPerRank; // after the bank, we get the rank bits which thus interleaves // over the ranks rank = addr % ranksPerChannel; addr = addr / ranksPerChannel; // lastly, get the row bits row = addr % rowsPerBank; addr = addr / rowsPerBank; } else if (addrMapping == Enums::RoCoRaBaCh) { // optimise for closed page mode and utilise maximum // parallelism of the DRAM (at the cost of power) // take out the channel part of the address, not that this has // to match with how accesses are interleaved between the // controllers in the address mapping addr = addr / channels; // start with the bank bits, as this provides the maximum // opportunity for parallelism between requests bank = addr % banksPerRank; addr = addr / banksPerRank; // next get the rank bits rank = addr % ranksPerChannel; addr = addr / ranksPerChannel; // next the column bits which we do not need to keep track of // and simply skip past addr = addr / columnsPerRowBuffer; // lastly, get the row bits row = addr % rowsPerBank; addr = addr / rowsPerBank; } else panic("Unknown address mapping policy chosen!"); assert(rank < ranksPerChannel); assert(bank < banksPerRank); assert(row < rowsPerBank); DPRINTF(DRAM, "Address: %lld Rank %d Bank %d Row %d\n", dramPktAddr, rank, bank, row); // create the corresponding DRAM packet with the entry time and // ready time set to the current tick, the latter will be updated // later uint16_t bank_id = banksPerRank * rank + bank; return new DRAMPacket(pkt, isRead, rank, bank, row, bank_id, dramPktAddr, size, banks[rank][bank]); } void DRAMCtrl::addToReadQueue(PacketPtr pkt, unsigned int pktCount) { // only add to the read queue here. whenever the request is // eventually done, set the readyTime, and call schedule() assert(!pkt->isWrite()); assert(pktCount != 0); // if the request size is larger than burst size, the pkt is split into // multiple DRAM packets // Note if the pkt starting address is not aligened to burst size, the // address of first DRAM packet is kept unaliged. Subsequent DRAM packets // are aligned to burst size boundaries. This is to ensure we accurately // check read packets against packets in write queue. Addr addr = pkt->getAddr(); unsigned pktsServicedByWrQ = 0; BurstHelper* burst_helper = NULL; for (int cnt = 0; cnt < pktCount; ++cnt) { unsigned size = std::min((addr | (burstSize - 1)) + 1, pkt->getAddr() + pkt->getSize()) - addr; readPktSize[ceilLog2(size)]++; readBursts++; // First check write buffer to see if the data is already at // the controller bool foundInWrQ = false; for (auto i = writeQueue.begin(); i != writeQueue.end(); ++i) { // check if the read is subsumed in the write entry we are // looking at if ((*i)->addr <= addr && (addr + size) <= ((*i)->addr + (*i)->size)) { foundInWrQ = true; servicedByWrQ++; pktsServicedByWrQ++; DPRINTF(DRAM, "Read to addr %lld with size %d serviced by " "write queue\n", addr, size); bytesReadWrQ += burstSize; break; } } // If not found in the write q, make a DRAM packet and // push it onto the read queue if (!foundInWrQ) { // Make the burst helper for split packets if (pktCount > 1 && burst_helper == NULL) { DPRINTF(DRAM, "Read to addr %lld translates to %d " "dram requests\n", pkt->getAddr(), pktCount); burst_helper = new BurstHelper(pktCount); } DRAMPacket* dram_pkt = decodeAddr(pkt, addr, size, true); dram_pkt->burstHelper = burst_helper; assert(!readQueueFull(1)); rdQLenPdf[readQueue.size() + respQueue.size()]++; DPRINTF(DRAM, "Adding to read queue\n"); readQueue.push_back(dram_pkt); // Update stats avgRdQLen = readQueue.size() + respQueue.size(); } // Starting address of next dram pkt (aligend to burstSize boundary) addr = (addr | (burstSize - 1)) + 1; } // If all packets are serviced by write queue, we send the repsonse back if (pktsServicedByWrQ == pktCount) { accessAndRespond(pkt, frontendLatency); return; } // Update how many split packets are serviced by write queue if (burst_helper != NULL) burst_helper->burstsServiced = pktsServicedByWrQ; // If we are not already scheduled to get a request out of the // queue, do so now if (!nextReqEvent.scheduled()) { DPRINTF(DRAM, "Request scheduled immediately\n"); schedule(nextReqEvent, curTick()); } } void DRAMCtrl::addToWriteQueue(PacketPtr pkt, unsigned int pktCount) { // only add to the write queue here. whenever the request is // eventually done, set the readyTime, and call schedule() assert(pkt->isWrite()); // if the request size is larger than burst size, the pkt is split into // multiple DRAM packets Addr addr = pkt->getAddr(); for (int cnt = 0; cnt < pktCount; ++cnt) { unsigned size = std::min((addr | (burstSize - 1)) + 1, pkt->getAddr() + pkt->getSize()) - addr; writePktSize[ceilLog2(size)]++; writeBursts++; // see if we can merge with an existing item in the write // queue and keep track of whether we have merged or not so we // can stop at that point and also avoid enqueueing a new // request bool merged = false; auto w = writeQueue.begin(); while(!merged && w != writeQueue.end()) { // either of the two could be first, if they are the same // it does not matter which way we go if ((*w)->addr >= addr) { // the existing one starts after the new one, figure // out where the new one ends with respect to the // existing one if ((addr + size) >= ((*w)->addr + (*w)->size)) { // check if the existing one is completely // subsumed in the new one DPRINTF(DRAM, "Merging write covering existing burst\n"); merged = true; // update both the address and the size (*w)->addr = addr; (*w)->size = size; } else if ((addr + size) >= (*w)->addr && ((*w)->addr + (*w)->size - addr) <= burstSize) { // the new one is just before or partially // overlapping with the existing one, and together // they fit within a burst DPRINTF(DRAM, "Merging write before existing burst\n"); merged = true; // the existing queue item needs to be adjusted with // respect to both address and size (*w)->size = (*w)->addr + (*w)->size - addr; (*w)->addr = addr; } } else { // the new one starts after the current one, figure // out where the existing one ends with respect to the // new one if (((*w)->addr + (*w)->size) >= (addr + size)) { // check if the new one is completely subsumed in the // existing one DPRINTF(DRAM, "Merging write into existing burst\n"); merged = true; // no adjustments necessary } else if (((*w)->addr + (*w)->size) >= addr && (addr + size - (*w)->addr) <= burstSize) { // the existing one is just before or partially // overlapping with the new one, and together // they fit within a burst DPRINTF(DRAM, "Merging write after existing burst\n"); merged = true; // the address is right, and only the size has // to be adjusted (*w)->size = addr + size - (*w)->addr; } } ++w; } // if the item was not merged we need to create a new write // and enqueue it if (!merged) { DRAMPacket* dram_pkt = decodeAddr(pkt, addr, size, false); assert(writeQueue.size() < writeBufferSize); wrQLenPdf[writeQueue.size()]++; DPRINTF(DRAM, "Adding to write queue\n"); writeQueue.push_back(dram_pkt); // Update stats avgWrQLen = writeQueue.size(); } else { // keep track of the fact that this burst effectively // disappeared as it was merged with an existing one mergedWrBursts++; } // Starting address of next dram pkt (aligend to burstSize boundary) addr = (addr | (burstSize - 1)) + 1; } // we do not wait for the writes to be send to the actual memory, // but instead take responsibility for the consistency here and // snoop the write queue for any upcoming reads // @todo, if a pkt size is larger than burst size, we might need a // different front end latency accessAndRespond(pkt, frontendLatency); // If we are not already scheduled to get a request out of the // queue, do so now if (!nextReqEvent.scheduled()) { DPRINTF(DRAM, "Request scheduled immediately\n"); schedule(nextReqEvent, curTick()); } } void DRAMCtrl::printParams() const { // Sanity check print of important parameters DPRINTF(DRAM, "Memory controller %s physical organization\n" \ "Number of devices per rank %d\n" \ "Device bus width (in bits) %d\n" \ "DRAM data bus burst (bytes) %d\n" \ "Row buffer size (bytes) %d\n" \ "Columns per row buffer %d\n" \ "Rows per bank %d\n" \ "Banks per rank %d\n" \ "Ranks per channel %d\n" \ "Total mem capacity (bytes) %u\n", name(), devicesPerRank, deviceBusWidth, burstSize, rowBufferSize, columnsPerRowBuffer, rowsPerBank, banksPerRank, ranksPerChannel, rowBufferSize * rowsPerBank * banksPerRank * ranksPerChannel); string scheduler = memSchedPolicy == Enums::fcfs ? "FCFS" : "FR-FCFS"; string address_mapping = addrMapping == Enums::RoRaBaChCo ? "RoRaBaChCo" : (addrMapping == Enums::RoRaBaCoCh ? "RoRaBaCoCh" : "RoCoRaBaCh"); string page_policy = pageMgmt == Enums::open ? "OPEN" : (pageMgmt == Enums::open_adaptive ? "OPEN (adaptive)" : (pageMgmt == Enums::close_adaptive ? "CLOSE (adaptive)" : "CLOSE")); DPRINTF(DRAM, "Memory controller %s characteristics\n" \ "Read buffer size %d\n" \ "Write buffer size %d\n" \ "Write high thresh %d\n" \ "Write low thresh %d\n" \ "Scheduler %s\n" \ "Address mapping %s\n" \ "Page policy %s\n", name(), readBufferSize, writeBufferSize, writeHighThreshold, writeLowThreshold, scheduler, address_mapping, page_policy); DPRINTF(DRAM, "Memory controller %s timing specs\n" \ "tRCD %d ticks\n" \ "tCL %d ticks\n" \ "tRP %d ticks\n" \ "tBURST %d ticks\n" \ "tRFC %d ticks\n" \ "tREFI %d ticks\n" \ "tWTR %d ticks\n" \ "tRTW %d ticks\n" \ "tXAW (%d) %d ticks\n", name(), tRCD, tCL, tRP, tBURST, tRFC, tREFI, tWTR, tRTW, activationLimit, tXAW); } void DRAMCtrl::printQs() const { DPRINTF(DRAM, "===READ QUEUE===\n\n"); for (auto i = readQueue.begin() ; i != readQueue.end() ; ++i) { DPRINTF(DRAM, "Read %lu\n", (*i)->addr); } DPRINTF(DRAM, "\n===RESP QUEUE===\n\n"); for (auto i = respQueue.begin() ; i != respQueue.end() ; ++i) { DPRINTF(DRAM, "Response %lu\n", (*i)->addr); } DPRINTF(DRAM, "\n===WRITE QUEUE===\n\n"); for (auto i = writeQueue.begin() ; i != writeQueue.end() ; ++i) { DPRINTF(DRAM, "Write %lu\n", (*i)->addr); } } bool DRAMCtrl::recvTimingReq(PacketPtr pkt) { /// @todo temporary hack to deal with memory corruption issues until /// 4-phase transactions are complete for (int x = 0; x < pendingDelete.size(); x++) delete pendingDelete[x]; pendingDelete.clear(); // This is where we enter from the outside world DPRINTF(DRAM, "recvTimingReq: request %s addr %lld size %d\n", pkt->cmdString(), pkt->getAddr(), pkt->getSize()); // simply drop inhibited packets for now if (pkt->memInhibitAsserted()) { DPRINTF(DRAM, "Inhibited packet -- Dropping it now\n"); pendingDelete.push_back(pkt); return true; } // Calc avg gap between requests if (prevArrival != 0) { totGap += curTick() - prevArrival; } prevArrival = curTick(); // Find out how many dram packets a pkt translates to // If the burst size is equal or larger than the pkt size, then a pkt // translates to only one dram packet. Otherwise, a pkt translates to // multiple dram packets unsigned size = pkt->getSize(); unsigned offset = pkt->getAddr() & (burstSize - 1); unsigned int dram_pkt_count = divCeil(offset + size, burstSize); // check local buffers and do not accept if full if (pkt->isRead()) { assert(size != 0); if (readQueueFull(dram_pkt_count)) { DPRINTF(DRAM, "Read queue full, not accepting\n"); // remember that we have to retry this port retryRdReq = true; numRdRetry++; return false; } else { addToReadQueue(pkt, dram_pkt_count); readReqs++; bytesReadSys += size; } } else if (pkt->isWrite()) { assert(size != 0); if (writeQueueFull(dram_pkt_count)) { DPRINTF(DRAM, "Write queue full, not accepting\n"); // remember that we have to retry this port retryWrReq = true; numWrRetry++; return false; } else { addToWriteQueue(pkt, dram_pkt_count); writeReqs++; bytesWrittenSys += size; } } else { DPRINTF(DRAM,"Neither read nor write, ignore timing\n"); neitherReadNorWrite++; accessAndRespond(pkt, 1); } return true; } void DRAMCtrl::processRespondEvent() { DPRINTF(DRAM, "processRespondEvent(): Some req has reached its readyTime\n"); DRAMPacket* dram_pkt = respQueue.front(); if (dram_pkt->burstHelper) { // it is a split packet dram_pkt->burstHelper->burstsServiced++; if (dram_pkt->burstHelper->burstsServiced == dram_pkt->burstHelper->burstCount) { // we have now serviced all children packets of a system packet // so we can now respond to the requester // @todo we probably want to have a different front end and back // end latency for split packets accessAndRespond(dram_pkt->pkt, frontendLatency + backendLatency); delete dram_pkt->burstHelper; dram_pkt->burstHelper = NULL; } } else { // it is not a split packet accessAndRespond(dram_pkt->pkt, frontendLatency + backendLatency); } delete respQueue.front(); respQueue.pop_front(); if (!respQueue.empty()) { assert(respQueue.front()->readyTime >= curTick()); assert(!respondEvent.scheduled()); schedule(respondEvent, respQueue.front()->readyTime); } else { // if there is nothing left in any queue, signal a drain if (writeQueue.empty() && readQueue.empty() && drainManager) { drainManager->signalDrainDone(); drainManager = NULL; } } // We have made a location in the queue available at this point, // so if there is a read that was forced to wait, retry now if (retryRdReq) { retryRdReq = false; port.sendRetry(); } } void DRAMCtrl::chooseNext(std::deque& queue) { // This method does the arbitration between requests. The chosen // packet is simply moved to the head of the queue. The other // methods know that this is the place to look. For example, with // FCFS, this method does nothing assert(!queue.empty()); if (queue.size() == 1) { DPRINTF(DRAM, "Single request, nothing to do\n"); return; } if (memSchedPolicy == Enums::fcfs) { // Do nothing, since the correct request is already head } else if (memSchedPolicy == Enums::frfcfs) { reorderQueue(queue); } else panic("No scheduling policy chosen\n"); } void DRAMCtrl::reorderQueue(std::deque& queue) { // Only determine this when needed uint64_t earliest_banks = 0; // Search for row hits first, if no row hit is found then schedule the // packet to one of the earliest banks available bool found_earliest_pkt = false; auto selected_pkt_it = queue.begin(); for (auto i = queue.begin(); i != queue.end() ; ++i) { DRAMPacket* dram_pkt = *i; const Bank& bank = dram_pkt->bankRef; // Check if it is a row hit if (bank.openRow == dram_pkt->row) { DPRINTF(DRAM, "Row buffer hit\n"); selected_pkt_it = i; break; } else if (!found_earliest_pkt) { // No row hit, go for first ready if (earliest_banks == 0) earliest_banks = minBankFreeAt(queue); // Bank is ready or is the first available bank if (bank.freeAt <= curTick() || bits(earliest_banks, dram_pkt->bankId, dram_pkt->bankId)) { // Remember the packet to be scheduled to one of the earliest // banks available selected_pkt_it = i; found_earliest_pkt = true; } } } DRAMPacket* selected_pkt = *selected_pkt_it; queue.erase(selected_pkt_it); queue.push_front(selected_pkt); } void DRAMCtrl::accessAndRespond(PacketPtr pkt, Tick static_latency) { DPRINTF(DRAM, "Responding to Address %lld.. ",pkt->getAddr()); bool needsResponse = pkt->needsResponse(); // do the actual memory access which also turns the packet into a // response access(pkt); // turn packet around to go back to requester if response expected if (needsResponse) { // access already turned the packet into a response assert(pkt->isResponse()); // @todo someone should pay for this pkt->busFirstWordDelay = pkt->busLastWordDelay = 0; // queue the packet in the response queue to be sent out after // the static latency has passed port.schedTimingResp(pkt, curTick() + static_latency); } else { // @todo the packet is going to be deleted, and the DRAMPacket // is still having a pointer to it pendingDelete.push_back(pkt); } DPRINTF(DRAM, "Done\n"); return; } pair DRAMCtrl::estimateLatency(DRAMPacket* dram_pkt, Tick inTime) { // If a request reaches a bank at tick 'inTime', how much time // *after* that does it take to finish the request, depending // on bank status and page open policy. Note that this method // considers only the time taken for the actual read or write // to complete, NOT any additional time thereafter for tRAS or // tRP. Tick accLat = 0; Tick bankLat = 0; rowHitFlag = false; Tick potentialActTick; const Bank& bank = dram_pkt->bankRef; // open-page policy or close_adaptive policy if (pageMgmt == Enums::open || pageMgmt == Enums::open_adaptive || pageMgmt == Enums::close_adaptive) { if (bank.openRow == dram_pkt->row) { // When we have a row-buffer hit, // we don't care about tRAS having expired or not, // but do care about bank being free for access rowHitFlag = true; // When a series of requests arrive to the same row, // DDR systems are capable of streaming data continuously // at maximum bandwidth (subject to tCCD). Here, we approximate // this condition, and assume that if whenever a bank is already // busy and a new request comes in, it can be completed with no // penalty beyond waiting for the existing read to complete. if (bank.freeAt > inTime) { accLat += bank.freeAt - inTime; bankLat += 0; } else { // CAS latency only accLat += tCL; bankLat += tCL; } } else { // Row-buffer miss, need to close existing row // once tRAS has expired, then open the new one, // then add cas latency. Tick freeTime = std::max(bank.tRASDoneAt, bank.freeAt); if (freeTime > inTime) accLat += freeTime - inTime; // If the there is no open row (open adaptive), then there // is no precharge delay, otherwise go with tRP Tick precharge_delay = bank.openRow == Bank::NO_ROW ? 0 : tRP; //The bank is free, and you may be able to activate potentialActTick = inTime + accLat + precharge_delay; if (potentialActTick < bank.actAllowedAt) accLat += bank.actAllowedAt - potentialActTick; accLat += precharge_delay + tRCD + tCL; bankLat += precharge_delay + tRCD + tCL; } } else if (pageMgmt == Enums::close) { // With a close page policy, no notion of // bank.tRASDoneAt if (bank.freeAt > inTime) accLat += bank.freeAt - inTime; //The bank is free, and you may be able to activate potentialActTick = inTime + accLat; if (potentialActTick < bank.actAllowedAt) accLat += bank.actAllowedAt - potentialActTick; // page already closed, simply open the row, and // add cas latency accLat += tRCD + tCL; bankLat += tRCD + tCL; } else panic("No page management policy chosen\n"); DPRINTF(DRAM, "Returning < %lld, %lld > from estimateLatency()\n", bankLat, accLat); return make_pair(bankLat, accLat); } void DRAMCtrl::recordActivate(Tick act_tick, uint8_t rank, uint8_t bank, uint16_t row) { assert(0 <= rank && rank < ranksPerChannel); assert(actTicks[rank].size() == activationLimit); DPRINTF(DRAM, "Activate at tick %d\n", act_tick); // update the open row assert(banks[rank][bank].openRow == Bank::NO_ROW); banks[rank][bank].openRow = row; // start counting anew, this covers both the case when we // auto-precharged, and when this access is forced to // precharge banks[rank][bank].bytesAccessed = 0; banks[rank][bank].rowAccesses = 0; ++numBanksActive; assert(numBanksActive <= banksPerRank * ranksPerChannel); DPRINTF(DRAM, "Activate bank at tick %lld, now got %d active\n", act_tick, numBanksActive); // start by enforcing tRRD for(int i = 0; i < banksPerRank; i++) { // next activate must not happen before tRRD banks[rank][i].actAllowedAt = act_tick + tRRD; } // tRC should be added to activation tick of the bank currently accessed, // where tRC = tRAS + tRP, this is just for a check as actAllowedAt for same // bank is already captured by bank.freeAt and bank.tRASDoneAt banks[rank][bank].actAllowedAt = act_tick + tRAS + tRP; // next, we deal with tXAW, if the activation limit is disabled // then we are done if (actTicks[rank].empty()) return; // sanity check if (actTicks[rank].back() && (act_tick - actTicks[rank].back()) < tXAW) { // @todo For now, stick with a warning warn("Got %d activates in window %d (%d - %d) which is smaller " "than %d\n", activationLimit, act_tick - actTicks[rank].back(), act_tick, actTicks[rank].back(), tXAW); } // shift the times used for the book keeping, the last element // (highest index) is the oldest one and hence the lowest value actTicks[rank].pop_back(); // record an new activation (in the future) actTicks[rank].push_front(act_tick); // cannot activate more than X times in time window tXAW, push the // next one (the X + 1'st activate) to be tXAW away from the // oldest in our window of X if (actTicks[rank].back() && (act_tick - actTicks[rank].back()) < tXAW) { DPRINTF(DRAM, "Enforcing tXAW with X = %d, next activate no earlier " "than %d\n", activationLimit, actTicks[rank].back() + tXAW); for(int j = 0; j < banksPerRank; j++) // next activate must not happen before end of window banks[rank][j].actAllowedAt = actTicks[rank].back() + tXAW; } // at the point when this activate takes place, make sure we // transition to the active power state if (!activateEvent.scheduled()) schedule(activateEvent, act_tick); else if (activateEvent.when() > act_tick) // move it sooner in time reschedule(activateEvent, act_tick); } void DRAMCtrl::processActivateEvent() { // we should transition to the active state as soon as any bank is active if (pwrState != PWR_ACT) // note that at this point numBanksActive could be back at // zero again due to a precharge scheduled in the future schedulePowerEvent(PWR_ACT, curTick()); } void DRAMCtrl::prechargeBank(Bank& bank, Tick free_at) { // make sure the bank has an open row assert(bank.openRow != Bank::NO_ROW); // sample the bytes per activate here since we are closing // the page bytesPerActivate.sample(bank.bytesAccessed); bank.openRow = Bank::NO_ROW; bank.freeAt = free_at; assert(numBanksActive != 0); --numBanksActive; DPRINTF(DRAM, "Precharged bank, done at tick %lld, now got %d active\n", bank.freeAt, numBanksActive); // if we look at the current number of active banks we might be // tempted to think the DRAM is now idle, however this can be // undone by an activate that is scheduled to happen before we // would have reached the idle state, so schedule an event and // rather check once we actually make it to the point in time when // the (last) precharge takes place if (!prechargeEvent.scheduled()) schedule(prechargeEvent, free_at); else if (prechargeEvent.when() < free_at) reschedule(prechargeEvent, free_at); } void DRAMCtrl::processPrechargeEvent() { // if we reached zero, then special conditions apply as we track // if all banks are precharged for the power models if (numBanksActive == 0) { // we should transition to the idle state when the last bank // is precharged schedulePowerEvent(PWR_IDLE, curTick()); } } void DRAMCtrl::doDRAMAccess(DRAMPacket* dram_pkt) { DPRINTF(DRAM, "Timing access to addr %lld, rank/bank/row %d %d %d\n", dram_pkt->addr, dram_pkt->rank, dram_pkt->bank, dram_pkt->row); // estimate the bank and access latency pair lat = estimateLatency(dram_pkt, curTick()); Tick bankLat = lat.first; Tick accessLat = lat.second; Tick actTick; // This request was woken up at this time based on a prior call // to estimateLatency(). However, between then and now, both the // accessLatency and/or busBusyUntil may have changed. We need // to correct for that. Tick addDelay = (curTick() + accessLat < busBusyUntil) ? busBusyUntil - (curTick() + accessLat) : 0; Bank& bank = dram_pkt->bankRef; // Update bank state if (pageMgmt == Enums::open || pageMgmt == Enums::open_adaptive || pageMgmt == Enums::close_adaptive) { if (rowHitFlag) { bank.freeAt = curTick() + addDelay + accessLat; } else { // If there is a page open, precharge it. if (bank.openRow != Bank::NO_ROW) { prechargeBank(bank, std::max(std::max(bank.freeAt, bank.tRASDoneAt), curTick()) + tRP); } // Any precharge is already part of the latency // estimation, so update the bank free time bank.freeAt = curTick() + addDelay + accessLat; // any waiting for banks account for in freeAt actTick = bank.freeAt - tCL - tRCD; // If you activated a new row do to this access, the next access // will have to respect tRAS for this bank bank.tRASDoneAt = actTick + tRAS; recordActivate(actTick, dram_pkt->rank, dram_pkt->bank, dram_pkt->row); } // increment the bytes accessed and the accesses per row bank.bytesAccessed += burstSize; ++bank.rowAccesses; // if we reached the max, then issue with an auto-precharge bool auto_precharge = bank.rowAccesses == maxAccessesPerRow; // if we did not hit the limit, we might still want to // auto-precharge if (!auto_precharge && (pageMgmt == Enums::open_adaptive || pageMgmt == Enums::close_adaptive)) { // a twist on the open and close page policies: // 1) open_adaptive page policy does not blindly keep the // page open, but close it if there are no row hits, and there // are bank conflicts in the queue // 2) close_adaptive page policy does not blindly close the // page, but closes it only if there are no row hits in the queue. // In this case, only force an auto precharge when there // are no same page hits in the queue bool got_more_hits = false; bool got_bank_conflict = false; // either look at the read queue or write queue const deque& queue = dram_pkt->isRead ? readQueue : writeQueue; auto p = queue.begin(); // make sure we are not considering the packet that we are // currently dealing with (which is the head of the queue) ++p; // keep on looking until we have found required condition or // reached the end while (!(got_more_hits && (got_bank_conflict || pageMgmt == Enums::close_adaptive)) && p != queue.end()) { bool same_rank_bank = (dram_pkt->rank == (*p)->rank) && (dram_pkt->bank == (*p)->bank); bool same_row = dram_pkt->row == (*p)->row; got_more_hits |= same_rank_bank && same_row; got_bank_conflict |= same_rank_bank && !same_row; ++p; } // auto pre-charge when either // 1) open_adaptive policy, we have not got any more hits, and // have a bank conflict // 2) close_adaptive policy and we have not got any more hits auto_precharge = !got_more_hits && (got_bank_conflict || pageMgmt == Enums::close_adaptive); } // if this access should use auto-precharge, then we are // closing the row if (auto_precharge) { prechargeBank(bank, std::max(bank.freeAt, bank.tRASDoneAt) + tRP); DPRINTF(DRAM, "Auto-precharged bank: %d\n", dram_pkt->bankId); } DPRINTF(DRAM, "doDRAMAccess::bank.freeAt is %lld\n", bank.freeAt); } else if (pageMgmt == Enums::close) { actTick = curTick() + addDelay + accessLat - tRCD - tCL; recordActivate(actTick, dram_pkt->rank, dram_pkt->bank, dram_pkt->row); bank.freeAt = actTick + tRCD + tCL; bank.tRASDoneAt = actTick + tRAS; // sample the relevant values when precharging bank.bytesAccessed = burstSize; bank.rowAccesses = 1; prechargeBank(bank, std::max(bank.freeAt, bank.tRASDoneAt) + tRP); DPRINTF(DRAM, "doDRAMAccess::bank.freeAt is %lld\n", bank.freeAt); } else panic("No page management policy chosen\n"); // Update request parameters dram_pkt->readyTime = curTick() + addDelay + accessLat + tBURST; DPRINTF(DRAM, "Req %lld: curtick is %lld accessLat is %d " \ "readytime is %lld busbusyuntil is %lld. " \ "Scheduling at readyTime\n", dram_pkt->addr, curTick(), accessLat, dram_pkt->readyTime, busBusyUntil); // Make sure requests are not overlapping on the databus assert(dram_pkt->readyTime - busBusyUntil >= tBURST); // Update bus state busBusyUntil = dram_pkt->readyTime; DPRINTF(DRAM,"Access time is %lld\n", dram_pkt->readyTime - dram_pkt->entryTime); // Update the minimum timing between the requests, this is a // conservative estimate of when we have to schedule the next // request to not introduce any unecessary bubbles. In most cases // we will wake up sooner than we have to. nextReqTime = busBusyUntil - (tRP + tRCD + tCL); // Update the stats and schedule the next request if (dram_pkt->isRead) { ++readsThisTime; if (rowHitFlag) readRowHits++; bytesReadDRAM += burstSize; perBankRdBursts[dram_pkt->bankId]++; // Update latency stats totMemAccLat += dram_pkt->readyTime - dram_pkt->entryTime; totBankLat += bankLat; totBusLat += tBURST; totQLat += dram_pkt->readyTime - dram_pkt->entryTime - bankLat - tBURST; } else { ++writesThisTime; if (rowHitFlag) writeRowHits++; bytesWritten += burstSize; perBankWrBursts[dram_pkt->bankId]++; } } void DRAMCtrl::moveToRespQ() { // Remove from read queue DRAMPacket* dram_pkt = readQueue.front(); readQueue.pop_front(); // sanity check assert(dram_pkt->size <= burstSize); // Insert into response queue sorted by readyTime // It will be sent back to the requestor at its // readyTime if (respQueue.empty()) { respQueue.push_front(dram_pkt); assert(!respondEvent.scheduled()); assert(dram_pkt->readyTime >= curTick()); schedule(respondEvent, dram_pkt->readyTime); } else { bool done = false; auto i = respQueue.begin(); while (!done && i != respQueue.end()) { if ((*i)->readyTime > dram_pkt->readyTime) { respQueue.insert(i, dram_pkt); done = true; } ++i; } if (!done) respQueue.push_back(dram_pkt); assert(respondEvent.scheduled()); if (respQueue.front()->readyTime < respondEvent.when()) { assert(respQueue.front()->readyTime >= curTick()); reschedule(respondEvent, respQueue.front()->readyTime); } } } void DRAMCtrl::processNextReqEvent() { if (busState == READ_TO_WRITE) { DPRINTF(DRAM, "Switching to writes after %d reads with %d reads " "waiting\n", readsThisTime, readQueue.size()); // sample and reset the read-related stats as we are now // transitioning to writes, and all reads are done rdPerTurnAround.sample(readsThisTime); readsThisTime = 0; // now proceed to do the actual writes busState = WRITE; } else if (busState == WRITE_TO_READ) { DPRINTF(DRAM, "Switching to reads after %d writes with %d writes " "waiting\n", writesThisTime, writeQueue.size()); wrPerTurnAround.sample(writesThisTime); writesThisTime = 0; busState = READ; } if (refreshState != REF_IDLE) { // if a refresh waiting for this event loop to finish, then hand // over now, and do not schedule a new nextReqEvent if (refreshState == REF_DRAIN) { DPRINTF(DRAM, "Refresh drain done, now precharging\n"); refreshState = REF_PRE; // hand control back to the refresh event loop schedule(refreshEvent, curTick()); } // let the refresh finish before issuing any further requests return; } // when we get here it is either a read or a write if (busState == READ) { // track if we should switch or not bool switch_to_writes = false; if (readQueue.empty()) { // In the case there is no read request to go next, // trigger writes if we have passed the low threshold (or // if we are draining) if (!writeQueue.empty() && (drainManager || writeQueue.size() > writeLowThreshold)) { switch_to_writes = true; } else { // check if we are drained if (respQueue.empty () && drainManager) { drainManager->signalDrainDone(); drainManager = NULL; } // nothing to do, not even any point in scheduling an // event for the next request return; } } else { // Figure out which read request goes next, and move it to the // front of the read queue chooseNext(readQueue); doDRAMAccess(readQueue.front()); // At this point we're done dealing with the request // It will be moved to a separate response queue with a // correct readyTime, and eventually be sent back at that // time moveToRespQ(); // we have so many writes that we have to transition if (writeQueue.size() > writeHighThreshold) { switch_to_writes = true; } } // switching to writes, either because the read queue is empty // and the writes have passed the low threshold (or we are // draining), or because the writes hit the hight threshold if (switch_to_writes) { // transition to writing busState = READ_TO_WRITE; // add a bubble to the data bus, as defined by the // tRTW parameter busBusyUntil += tRTW; // update the minimum timing between the requests, // this shifts us back in time far enough to do any // bank preparation nextReqTime = busBusyUntil - (tRP + tRCD + tCL); } } else { chooseNext(writeQueue); DRAMPacket* dram_pkt = writeQueue.front(); // sanity check assert(dram_pkt->size <= burstSize); doDRAMAccess(dram_pkt); writeQueue.pop_front(); delete dram_pkt; // If we emptied the write queue, or got sufficiently below the // threshold (using the minWritesPerSwitch as the hysteresis) and // are not draining, or we have reads waiting and have done enough // writes, then switch to reads. if (writeQueue.empty() || (writeQueue.size() + minWritesPerSwitch < writeLowThreshold && !drainManager) || (!readQueue.empty() && writesThisTime >= minWritesPerSwitch)) { // turn the bus back around for reads again busState = WRITE_TO_READ; // note that the we switch back to reads also in the idle // case, which eventually will check for any draining and // also pause any further scheduling if there is really // nothing to do // here we get a bit creative and shift the bus busy time not // just the tWTR, but also a CAS latency to capture the fact // that we are allowed to prepare a new bank, but not issue a // read command until after tWTR, in essence we capture a // bubble on the data bus that is tWTR + tCL busBusyUntil += tWTR + tCL; // update the minimum timing between the requests, this shifts // us back in time far enough to do any bank preparation nextReqTime = busBusyUntil - (tRP + tRCD + tCL); } } schedule(nextReqEvent, std::max(nextReqTime, curTick())); // If there is space available and we have writes waiting then let // them retry. This is done here to ensure that the retry does not // cause a nextReqEvent to be scheduled before we do so as part of // the next request processing if (retryWrReq && writeQueue.size() < writeBufferSize) { retryWrReq = false; port.sendRetry(); } } uint64_t DRAMCtrl::minBankFreeAt(const deque& queue) const { uint64_t bank_mask = 0; Tick freeAt = MaxTick; // detemrine if we have queued transactions targetting the // bank in question vector got_waiting(ranksPerChannel * banksPerRank, false); for (auto p = queue.begin(); p != queue.end(); ++p) { got_waiting[(*p)->bankId] = true; } for (int i = 0; i < ranksPerChannel; i++) { for (int j = 0; j < banksPerRank; j++) { // if we have waiting requests for the bank, and it is // amongst the first available, update the mask if (got_waiting[i * banksPerRank + j] && banks[i][j].freeAt <= freeAt) { // reset bank mask if new minimum is found if (banks[i][j].freeAt < freeAt) bank_mask = 0; // set the bit corresponding to the available bank uint8_t bit_index = i * ranksPerChannel + j; replaceBits(bank_mask, bit_index, bit_index, 1); freeAt = banks[i][j].freeAt; } } } return bank_mask; } void DRAMCtrl::processRefreshEvent() { // when first preparing the refresh, remember when it was due if (refreshState == REF_IDLE) { // remember when the refresh is due refreshDueAt = curTick(); // proceed to drain refreshState = REF_DRAIN; DPRINTF(DRAM, "Refresh due\n"); } // let any scheduled read or write go ahead, after which it will // hand control back to this event loop if (refreshState == REF_DRAIN) { if (nextReqEvent.scheduled()) { // hand control over to the request loop until it is // evaluated next DPRINTF(DRAM, "Refresh awaiting draining\n"); return; } else { refreshState = REF_PRE; } } // at this point, ensure that all banks are precharged if (refreshState == REF_PRE) { // precharge any active bank if we are not already in the idle // state if (pwrState != PWR_IDLE) { DPRINTF(DRAM, "Precharging all\n"); for (int i = 0; i < ranksPerChannel; i++) { for (int j = 0; j < banksPerRank; j++) { if (banks[i][j].openRow != Bank::NO_ROW) { // respect both causality and any existing bank // constraints Tick free_at = std::max(std::max(banks[i][j].freeAt, banks[i][j].tRASDoneAt), curTick()) + tRP; prechargeBank(banks[i][j], free_at); } } } } else { DPRINTF(DRAM, "All banks already precharged, starting refresh\n"); // go ahead and kick the power state machine into gear if // we are already idle schedulePowerEvent(PWR_REF, curTick()); } refreshState = REF_RUN; assert(numBanksActive == 0); // wait for all banks to be precharged, at which point the // power state machine will transition to the idle state, and // automatically move to a refresh, at that point it will also // call this method to get the refresh event loop going again return; } // last but not least we perform the actual refresh if (refreshState == REF_RUN) { // should never get here with any banks active assert(numBanksActive == 0); assert(pwrState == PWR_REF); Tick banksFree = curTick() + tRFC; for (int i = 0; i < ranksPerChannel; i++) { for (int j = 0; j < banksPerRank; j++) { banks[i][j].freeAt = banksFree; } } // make sure we did not wait so long that we cannot make up // for it if (refreshDueAt + tREFI < banksFree) { fatal("Refresh was delayed so long we cannot catch up\n"); } // compensate for the delay in actually performing the refresh // when scheduling the next one schedule(refreshEvent, refreshDueAt + tREFI - tRP); assert(!powerEvent.scheduled()); // move to the idle power state once the refresh is done, this // will also move the refresh state machine to the refresh // idle state schedulePowerEvent(PWR_IDLE, banksFree); DPRINTF(DRAMState, "Refresh done at %llu and next refresh at %llu\n", banksFree, refreshDueAt + tREFI); } } void DRAMCtrl::schedulePowerEvent(PowerState pwr_state, Tick tick) { // respect causality assert(tick >= curTick()); if (!powerEvent.scheduled()) { DPRINTF(DRAMState, "Scheduling power event at %llu to state %d\n", tick, pwr_state); // insert the new transition pwrStateTrans = pwr_state; schedule(powerEvent, tick); } else { panic("Scheduled power event at %llu to state %d, " "with scheduled event at %llu to %d\n", tick, pwr_state, powerEvent.when(), pwrStateTrans); } } void DRAMCtrl::processPowerEvent() { // remember where we were, and for how long Tick duration = curTick() - pwrStateTick; PowerState prev_state = pwrState; // update the accounting pwrStateTime[prev_state] += duration; pwrState = pwrStateTrans; pwrStateTick = curTick(); if (pwrState == PWR_IDLE) { DPRINTF(DRAMState, "All banks precharged\n"); // if we were refreshing, make sure we start scheduling requests again if (prev_state == PWR_REF) { DPRINTF(DRAMState, "Was refreshing for %llu ticks\n", duration); assert(pwrState == PWR_IDLE); // kick things into action again refreshState = REF_IDLE; assert(!nextReqEvent.scheduled()); schedule(nextReqEvent, curTick()); } else { assert(prev_state == PWR_ACT); // if we have a pending refresh, and are now moving to // the idle state, direclty transition to a refresh if (refreshState == REF_RUN) { // there should be nothing waiting at this point assert(!powerEvent.scheduled()); // update the state in zero time and proceed below pwrState = PWR_REF; } } } // we transition to the refresh state, let the refresh state // machine know of this state update and let it deal with the // scheduling of the next power state transition as well as the // following refresh if (pwrState == PWR_REF) { DPRINTF(DRAMState, "Refreshing\n"); // kick the refresh event loop into action again, and that // in turn will schedule a transition to the idle power // state once the refresh is done assert(refreshState == REF_RUN); processRefreshEvent(); } } void DRAMCtrl::regStats() { using namespace Stats; AbstractMemory::regStats(); readReqs .name(name() + ".readReqs") .desc("Number of read requests accepted"); writeReqs .name(name() + ".writeReqs") .desc("Number of write requests accepted"); readBursts .name(name() + ".readBursts") .desc("Number of DRAM read bursts, " "including those serviced by the write queue"); writeBursts .name(name() + ".writeBursts") .desc("Number of DRAM write bursts, " "including those merged in the write queue"); servicedByWrQ .name(name() + ".servicedByWrQ") .desc("Number of DRAM read bursts serviced by the write queue"); mergedWrBursts .name(name() + ".mergedWrBursts") .desc("Number of DRAM write bursts merged with an existing one"); neitherReadNorWrite .name(name() + ".neitherReadNorWriteReqs") .desc("Number of requests that are neither read nor write"); perBankRdBursts .init(banksPerRank * ranksPerChannel) .name(name() + ".perBankRdBursts") .desc("Per bank write bursts"); perBankWrBursts .init(banksPerRank * ranksPerChannel) .name(name() + ".perBankWrBursts") .desc("Per bank write bursts"); avgRdQLen .name(name() + ".avgRdQLen") .desc("Average read queue length when enqueuing") .precision(2); avgWrQLen .name(name() + ".avgWrQLen") .desc("Average write queue length when enqueuing") .precision(2); totQLat .name(name() + ".totQLat") .desc("Total ticks spent queuing"); totBankLat .name(name() + ".totBankLat") .desc("Total ticks spent accessing banks"); totBusLat .name(name() + ".totBusLat") .desc("Total ticks spent in databus transfers"); totMemAccLat .name(name() + ".totMemAccLat") .desc("Total ticks spent from burst creation until serviced " "by the DRAM"); avgQLat .name(name() + ".avgQLat") .desc("Average queueing delay per DRAM burst") .precision(2); avgQLat = totQLat / (readBursts - servicedByWrQ); avgBankLat .name(name() + ".avgBankLat") .desc("Average bank access latency per DRAM burst") .precision(2); avgBankLat = totBankLat / (readBursts - servicedByWrQ); avgBusLat .name(name() + ".avgBusLat") .desc("Average bus latency per DRAM burst") .precision(2); avgBusLat = totBusLat / (readBursts - servicedByWrQ); avgMemAccLat .name(name() + ".avgMemAccLat") .desc("Average memory access latency per DRAM burst") .precision(2); avgMemAccLat = totMemAccLat / (readBursts - servicedByWrQ); numRdRetry .name(name() + ".numRdRetry") .desc("Number of times read queue was full causing retry"); numWrRetry .name(name() + ".numWrRetry") .desc("Number of times write queue was full causing retry"); readRowHits .name(name() + ".readRowHits") .desc("Number of row buffer hits during reads"); writeRowHits .name(name() + ".writeRowHits") .desc("Number of row buffer hits during writes"); readRowHitRate .name(name() + ".readRowHitRate") .desc("Row buffer hit rate for reads") .precision(2); readRowHitRate = (readRowHits / (readBursts - servicedByWrQ)) * 100; writeRowHitRate .name(name() + ".writeRowHitRate") .desc("Row buffer hit rate for writes") .precision(2); writeRowHitRate = (writeRowHits / (writeBursts - mergedWrBursts)) * 100; readPktSize .init(ceilLog2(burstSize) + 1) .name(name() + ".readPktSize") .desc("Read request sizes (log2)"); writePktSize .init(ceilLog2(burstSize) + 1) .name(name() + ".writePktSize") .desc("Write request sizes (log2)"); rdQLenPdf .init(readBufferSize) .name(name() + ".rdQLenPdf") .desc("What read queue length does an incoming req see"); wrQLenPdf .init(writeBufferSize) .name(name() + ".wrQLenPdf") .desc("What write queue length does an incoming req see"); bytesPerActivate .init(maxAccessesPerRow) .name(name() + ".bytesPerActivate") .desc("Bytes accessed per row activation") .flags(nozero); rdPerTurnAround .init(readBufferSize) .name(name() + ".rdPerTurnAround") .desc("Reads before turning the bus around for writes") .flags(nozero); wrPerTurnAround .init(writeBufferSize) .name(name() + ".wrPerTurnAround") .desc("Writes before turning the bus around for reads") .flags(nozero); bytesReadDRAM .name(name() + ".bytesReadDRAM") .desc("Total number of bytes read from DRAM"); bytesReadWrQ .name(name() + ".bytesReadWrQ") .desc("Total number of bytes read from write queue"); bytesWritten .name(name() + ".bytesWritten") .desc("Total number of bytes written to DRAM"); bytesReadSys .name(name() + ".bytesReadSys") .desc("Total read bytes from the system interface side"); bytesWrittenSys .name(name() + ".bytesWrittenSys") .desc("Total written bytes from the system interface side"); avgRdBW .name(name() + ".avgRdBW") .desc("Average DRAM read bandwidth in MiByte/s") .precision(2); avgRdBW = (bytesReadDRAM / 1000000) / simSeconds; avgWrBW .name(name() + ".avgWrBW") .desc("Average achieved write bandwidth in MiByte/s") .precision(2); avgWrBW = (bytesWritten / 1000000) / simSeconds; avgRdBWSys .name(name() + ".avgRdBWSys") .desc("Average system read bandwidth in MiByte/s") .precision(2); avgRdBWSys = (bytesReadSys / 1000000) / simSeconds; avgWrBWSys .name(name() + ".avgWrBWSys") .desc("Average system write bandwidth in MiByte/s") .precision(2); avgWrBWSys = (bytesWrittenSys / 1000000) / simSeconds; peakBW .name(name() + ".peakBW") .desc("Theoretical peak bandwidth in MiByte/s") .precision(2); peakBW = (SimClock::Frequency / tBURST) * burstSize / 1000000; busUtil .name(name() + ".busUtil") .desc("Data bus utilization in percentage") .precision(2); busUtil = (avgRdBW + avgWrBW) / peakBW * 100; totGap .name(name() + ".totGap") .desc("Total gap between requests"); avgGap .name(name() + ".avgGap") .desc("Average gap between requests") .precision(2); avgGap = totGap / (readReqs + writeReqs); // Stats for DRAM Power calculation based on Micron datasheet busUtilRead .name(name() + ".busUtilRead") .desc("Data bus utilization in percentage for reads") .precision(2); busUtilRead = avgRdBW / peakBW * 100; busUtilWrite .name(name() + ".busUtilWrite") .desc("Data bus utilization in percentage for writes") .precision(2); busUtilWrite = avgWrBW / peakBW * 100; pageHitRate .name(name() + ".pageHitRate") .desc("Row buffer hit rate, read and write combined") .precision(2); pageHitRate = (writeRowHits + readRowHits) / (writeBursts - mergedWrBursts + readBursts - servicedByWrQ) * 100; pwrStateTime .init(5) .name(name() + ".memoryStateTime") .desc("Time in different power states"); pwrStateTime.subname(0, "IDLE"); pwrStateTime.subname(1, "REF"); pwrStateTime.subname(2, "PRE_PDN"); pwrStateTime.subname(3, "ACT"); pwrStateTime.subname(4, "ACT_PDN"); } void DRAMCtrl::recvFunctional(PacketPtr pkt) { // rely on the abstract memory functionalAccess(pkt); } BaseSlavePort& DRAMCtrl::getSlavePort(const string &if_name, PortID idx) { if (if_name != "port") { return MemObject::getSlavePort(if_name, idx); } else { return port; } } unsigned int DRAMCtrl::drain(DrainManager *dm) { unsigned int count = port.drain(dm); // if there is anything in any of our internal queues, keep track // of that as well if (!(writeQueue.empty() && readQueue.empty() && respQueue.empty())) { DPRINTF(Drain, "DRAM controller not drained, write: %d, read: %d," " resp: %d\n", writeQueue.size(), readQueue.size(), respQueue.size()); ++count; drainManager = dm; // the only part that is not drained automatically over time // is the write queue, thus kick things into action if needed if (!writeQueue.empty() && !nextReqEvent.scheduled()) { schedule(nextReqEvent, curTick()); } } if (count) setDrainState(Drainable::Draining); else setDrainState(Drainable::Drained); return count; } DRAMCtrl::MemoryPort::MemoryPort(const std::string& name, DRAMCtrl& _memory) : QueuedSlavePort(name, &_memory, queue), queue(_memory, *this), memory(_memory) { } AddrRangeList DRAMCtrl::MemoryPort::getAddrRanges() const { AddrRangeList ranges; ranges.push_back(memory.getAddrRange()); return ranges; } void DRAMCtrl::MemoryPort::recvFunctional(PacketPtr pkt) { pkt->pushLabel(memory.name()); if (!queue.checkFunctional(pkt)) { // Default implementation of SimpleTimingPort::recvFunctional() // calls recvAtomic() and throws away the latency; we can save a // little here by just not calculating the latency. memory.recvFunctional(pkt); } pkt->popLabel(); } Tick DRAMCtrl::MemoryPort::recvAtomic(PacketPtr pkt) { return memory.recvAtomic(pkt); } bool DRAMCtrl::MemoryPort::recvTimingReq(PacketPtr pkt) { // pass it to the memory controller return memory.recvTimingReq(pkt); } DRAMCtrl* DRAMCtrlParams::create() { return new DRAMCtrl(this); }