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* Copyright (c) 2010-2019 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.
* Authors: Andreas Hansson
* Ani Udipi
* Neha Agarwal
* Omar Naji
* Wendy Elsasser
* Radhika Jagtap
#include "mem/dram_ctrl.hh"
#include "base/bitfield.hh"
#include "base/trace.hh"
#include "debug/DRAM.hh"
#include "debug/DRAMPower.hh"
#include "debug/DRAMState.hh"
#include "debug/Drain.hh"
#include "debug/QOS.hh"
#include "sim/system.hh"
using namespace std;
using namespace Data;
DRAMCtrl::DRAMCtrl(const DRAMCtrlParams* p) :
port(name() + ".port", *this), isTimingMode(false),
retryRdReq(false), retryWrReq(false),
nextReqEvent([this]{ processNextReqEvent(); }, name()),
respondEvent([this]{ processRespondEvent(); }, name()),
deviceBusWidth(p->device_bus_width), burstLength(p->burst_length),
burstSize((devicesPerRank * burstLength * deviceBusWidth) / 8),
rowBufferSize(devicesPerRank * deviceRowBufferSize),
columnsPerRowBuffer(rowBufferSize / burstSize),
columnsPerStripe(range.interleaved() ? range.granularity() / burstSize : 1),
bankGroupArch(p->bank_groups_per_rank > 0),
banksPerRank(p->banks_per_rank), rowsPerBank(0),
writeHighThreshold(writeBufferSize * p->write_high_thresh_perc / 100.0),
writeLowThreshold(writeBufferSize * p->write_low_thresh_perc / 100.0),
writesThisTime(0), readsThisTime(0),
tCK(p->tCK), tRTW(p->tRTW), tCS(p->tCS), tBURST(p->tBURST),
tCCD_L(p->tCCD_L), tRCD(p->tRCD), tCL(p->tCL), tRP(p->tRP), tRAS(p->tRAS),
tWR(p->tWR), tRTP(p->tRTP), tRFC(p->tRFC), tREFI(p->tREFI), tRRD(p->tRRD),
tRRD_L(p->tRRD_L), tXAW(p->tXAW), tXP(p->tXP), tXS(p->tXS),
activationLimit(p->activation_limit), rankToRankDly(tCS + tBURST),
wrToRdDly(tCL + tBURST + p->tWTR), rdToWrDly(tRTW + tBURST),
memSchedPolicy(p->mem_sched_policy), addrMapping(p->addr_mapping),
nextBurstAt(0), prevArrival(0),
activeRank(0), timeStampOffset(0),
lastStatsResetTick(0), enableDRAMPowerdown(p->enable_dram_powerdown)
// sanity check the ranks since we rely on bit slicing for the
// address decoding
fatal_if(!isPowerOf2(ranksPerChannel), "DRAM rank count of %d is not "
"allowed, must be a power of two\n", ranksPerChannel);
fatal_if(!isPowerOf2(burstSize), "DRAM burst size %d is not allowed, "
"must be a power of two\n", burstSize);
for (int i = 0; i < ranksPerChannel; i++) {
Rank* rank = new Rank(*this, p, i);
// 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,
// determine the rows per bank by looking at the total capacity
uint64_t capacity = ULL(1) << ceilLog2(AbstractMemory::size());
// determine the dram actual capacity from the DRAM config in Mbytes
uint64_t deviceCapacity = deviceSize / (1024 * 1024) * devicesPerRank *
// if actual DRAM size does not match memory capacity in system warn!
if (deviceCapacity != capacity / (1024 * 1024))
warn("DRAM device capacity (%d Mbytes) does not match the "
"address range assigned (%d Mbytes)\n", deviceCapacity,
capacity / (1024 * 1024));
DPRINTF(DRAM, "Memory capacity %lld (%lld) bytes\n", capacity,
DPRINTF(DRAM, "Row buffer size %d bytes with %d columns per row buffer\n",
rowBufferSize, columnsPerRowBuffer);
rowsPerBank = capacity / (rowBufferSize * banksPerRank * ranksPerChannel);
// 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);
// basic bank group architecture checks ->
if (bankGroupArch) {
// must have at least one bank per bank group
if (bankGroupsPerRank > banksPerRank) {
fatal("banks per rank (%d) must be equal to or larger than "
"banks groups per rank (%d)\n",
banksPerRank, bankGroupsPerRank);
// must have same number of banks in each bank group
if ((banksPerRank % bankGroupsPerRank) != 0) {
fatal("Banks per rank (%d) must be evenly divisible by bank groups "
"per rank (%d) for equal banks per bank group\n",
banksPerRank, bankGroupsPerRank);
// tCCD_L should be greater than minimal, back-to-back burst delay
if (tCCD_L <= tBURST) {
fatal("tCCD_L (%d) should be larger than tBURST (%d) when "
"bank groups per rank (%d) is greater than 1\n",
tCCD_L, tBURST, bankGroupsPerRank);
// tCCD_L_WR should be greater than minimal, back-to-back burst delay
if (tCCD_L_WR <= tBURST) {
fatal("tCCD_L_WR (%d) should be larger than tBURST (%d) when "
"bank groups per rank (%d) is greater than 1\n",
tCCD_L_WR, tBURST, bankGroupsPerRank);
// tRRD_L is greater than minimal, same bank group ACT-to-ACT delay
// some datasheets might specify it equal to tRRD
if (tRRD_L < tRRD) {
fatal("tRRD_L (%d) should be larger than tRRD (%d) when "
"bank groups per rank (%d) is greater than 1\n",
tRRD_L, tRRD, bankGroupsPerRank);
if (!port.isConnected()) {
fatal("DRAMCtrl %s is unconnected!\n", name());
} else {
// a bit of sanity checks on the interleaving, save it for here to
// ensure that the system pointer is initialised
if (range.interleaved()) {
if (addrMapping == Enums::RoRaBaChCo) {
if (rowBufferSize != range.granularity()) {
fatal("Channel interleaving of %s doesn't match RoRaBaChCo "
"address map\n", name());
} else if (addrMapping == Enums::RoRaBaCoCh ||
addrMapping == Enums::RoCoRaBaCh) {
// for the interleavings with channel bits in the bottom,
// if the system uses a channel striping granularity that
// is larger than the DRAM burst size, then map the
// sequential accesses within a stripe to a number of
// columns in the DRAM, effectively placing some of the
// lower-order column bits as the least-significant bits
// of the address (above the ones denoting the burst size)
assert(columnsPerStripe >= 1);
// channel striping has to be done at a granularity that
// is equal or larger to a cache line
if (system()->cacheLineSize() > range.granularity()) {
fatal("Channel interleaving of %s must be at least as large "
"as the cache line size\n", name());
// ...and equal or smaller than the row-buffer size
if (rowBufferSize < range.granularity()) {
fatal("Channel interleaving of %s must be at most as large "
"as the row-buffer size\n", name());
// this is essentially the check above, so just to be sure
assert(columnsPerStripe <= columnsPerRowBuffer);
// remember the memory system mode of operation
isTimingMode = system()->isTimingMode();
if (isTimingMode) {
// timestamp offset should be in clock cycles for DRAMPower
timeStampOffset = divCeil(curTick(), tCK);
// update the start tick for the precharge accounting to the
// current tick
for (auto r : ranks) {
r->startup(curTick() + tREFI - tRP);
// 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
nextBurstAt = curTick() + tRP + tRCD;
DRAMCtrl::recvAtomic(PacketPtr pkt)
DPRINTF(DRAM, "recvAtomic: %s 0x%x\n", pkt->cmdString(), pkt->getAddr());
panic_if(pkt->cacheResponding(), "Should not see packets where cache "
"is responding");
// do the actual memory access and turn the packet into a response
Tick latency = 0;
if (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;
DRAMCtrl::readQueueFull(unsigned int neededEntries) const
DPRINTF(DRAM, "Read queue limit %d, current size %d, entries needed %d\n",
readBufferSize, totalReadQueueSize + respQueue.size(),
auto rdsize_new = totalReadQueueSize + respQueue.size() + neededEntries;
return rdsize_new > readBufferSize;
DRAMCtrl::writeQueueFull(unsigned int neededEntries) const
DPRINTF(DRAM, "Write queue limit %d, current size %d, entries needed %d\n",
writeBufferSize, totalWriteQueueSize, neededEntries);
auto wrsize_new = (totalWriteQueueSize + neededEntries);
return wrsize_new > writeBufferSize;
DRAMCtrl::decodeAddr(const PacketPtr pkt, Addr dramPktAddr, unsigned size,
bool isRead) const
// 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;
// use a 64-bit unsigned during the computations as the row is
// always the top bits, and check before creating the DRAMPacket
uint64_t row;
// truncate the address to a DRAM burst, which makes it unique to
// a specific column, row, bank, rank and channel
Addr addr = dramPktAddr / burstSize;
// we have removed the lowest order address bits that denote the
// position within the column
if (addrMapping == Enums::RoRaBaChCo || addrMapping == Enums::RoRaBaCoCh) {
// the lowest order bits denote the column to ensure that
// sequential cache lines occupy the same row
addr = addr / columnsPerRowBuffer;
// 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, no need to remove them from addr
row = 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 lower-order column bits
addr = addr / columnsPerStripe;
// 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 higher-order column bites
addr = addr / (columnsPerRowBuffer / columnsPerStripe);
// lastly, get the row bits, no need to remove them from addr
row = addr % rowsPerBank;
} else
panic("Unknown address mapping policy chosen!");
assert(rank < ranksPerChannel);
assert(bank < banksPerRank);
assert(row < rowsPerBank);
assert(row < Bank::NO_ROW);
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, ranks[rank]->banks[bank], *ranks[rank]);
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(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.
const Addr base_addr = getCtrlAddr(pkt->getAddr());
Addr addr = base_addr;
unsigned pktsServicedByWrQ = 0;
BurstHelper* burst_helper = NULL;
for (int cnt = 0; cnt < pktCount; ++cnt) {
unsigned size = std::min((addr | (burstSize - 1)) + 1,
base_addr + pkt->getSize()) - addr;
// First check write buffer to see if the data is already at
// the controller
bool foundInWrQ = false;
Addr burst_addr = burstAlign(addr);
// if the burst address is not present then there is no need
// looking any further
if (isInWriteQueue.find(burst_addr) != isInWriteQueue.end()) {
for (const auto& vec : writeQueue) {
for (const auto& p : vec) {
// check if the read is subsumed in the write queue
// packet we are looking at
if (p->addr <= addr &&
((addr + size) <= (p->addr + p->size))) {
foundInWrQ = true;
"Read to addr %lld with size %d serviced by "
"write queue\n",
addr, size);
stats.bytesReadWrQ += burstSize;
// 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;
stats.rdQLenPdf[totalReadQueueSize + respQueue.size()]++;
DPRINTF(DRAM, "Adding to read queue\n");
// log packet
logRequest(MemCtrl::READ, pkt->masterId(), pkt->qosValue(),
dram_pkt->addr, 1);
// Update stats
stats.avgRdQLen = totalReadQueueSize + 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);
// 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());
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()
// if the request size is larger than burst size, the pkt is split into
// multiple DRAM packets
const Addr base_addr = getCtrlAddr(pkt->getAddr());
Addr addr = base_addr;
for (int cnt = 0; cnt < pktCount; ++cnt) {
unsigned size = std::min((addr | (burstSize - 1)) + 1,
base_addr + pkt->getSize()) - addr;
// see if we can merge with an existing item in the write
// queue and keep track of whether we have merged or not
bool merged = isInWriteQueue.find(burstAlign(addr)) !=
// 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(totalWriteQueueSize < writeBufferSize);
DPRINTF(DRAM, "Adding to write queue\n");
// log packet
logRequest(MemCtrl::WRITE, pkt->masterId(), pkt->qosValue(),
dram_pkt->addr, 1);
assert(totalWriteQueueSize == isInWriteQueue.size());
// Update stats
stats.avgWrQLen = totalWriteQueueSize;
// increment write entries of the rank
} else {
DPRINTF(DRAM, "Merging write burst with existing queue entry\n");
// keep track of the fact that this burst effectively
// disappeared as it was merged with an existing one
// 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());
DRAMCtrl::printQs() const
for (const auto& queue : readQueue) {
for (const auto& packet : queue) {
DPRINTF(DRAM, "Read %lu\n", packet->addr);
DPRINTF(DRAM, "\n===RESP QUEUE===\n\n");
for (const auto& packet : respQueue) {
DPRINTF(DRAM, "Response %lu\n", packet->addr);
for (const auto& queue : writeQueue) {
for (const auto& packet : queue) {
DPRINTF(DRAM, "Write %lu\n", packet->addr);
#endif // TRACING_ON
DRAMCtrl::recvTimingReq(PacketPtr pkt)
// 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());
panic_if(pkt->cacheResponding(), "Should not see packets where cache "
"is responding");
panic_if(!(pkt->isRead() || pkt->isWrite()),
"Should only see read and writes at memory controller\n");
// Calc avg gap between requests
if (prevArrival != 0) {
stats.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);
// run the QoS scheduler and assign a QoS priority value to the packet
qosSchedule( { &readQueue, &writeQueue }, burstSize, pkt);
// check local buffers and do not accept if full
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;
return false;
} else {
addToWriteQueue(pkt, dram_pkt_count);
stats.bytesWrittenSys += size;
} else {
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;
return false;
} else {
addToReadQueue(pkt, dram_pkt_count);
stats.bytesReadSys += size;
return true;
"processRespondEvent(): Some req has reached its readyTime\n");
DRAMPacket* dram_pkt = respQueue.front();
// if a read has reached its ready-time, decrement the number of reads
// At this point the packet has been handled and there is a possibility
// to switch to low-power mode if no other packet is available
DPRINTF(DRAM, "number of read entries for rank %d is %d\n",
dram_pkt->rank, dram_pkt->rankRef.readEntries);
// counter should at least indicate one outstanding request
// for this read
assert(dram_pkt->rankRef.outstandingEvents > 0);
// read response received, decrement count
// at this moment should not have transitioned to a low-power state
assert((dram_pkt->rankRef.pwrState != PWR_SREF) &&
(dram_pkt->rankRef.pwrState != PWR_PRE_PDN) &&
(dram_pkt->rankRef.pwrState != PWR_ACT_PDN));
// track if this is the last packet before idling
// and that there are no outstanding commands to this rank
if (dram_pkt->rankRef.isQueueEmpty() &&
dram_pkt->rankRef.outstandingEvents == 0 && enableDRAMPowerdown) {
// verify that there are no events scheduled
// if coming from active state, schedule power event to
// active power-down else go to precharge power-down
DPRINTF(DRAMState, "Rank %d sleep at tick %d; current power state is "
"%d\n", dram_pkt->rank, curTick(), dram_pkt->rankRef.pwrState);
// default to ACT power-down unless already in IDLE state
// could be in IDLE if PRE issued before data returned
PowerState next_pwr_state = PWR_ACT_PDN;
if (dram_pkt->rankRef.pwrState == PWR_IDLE) {
next_pwr_state = PWR_PRE_PDN;
dram_pkt->rankRef.powerDownSleep(next_pwr_state, curTick());
if (dram_pkt->burstHelper) {
// it is a split packet
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();
if (!respQueue.empty()) {
assert(respQueue.front()->readyTime >= curTick());
schedule(respondEvent, respQueue.front()->readyTime);
} else {
// if there is nothing left in any queue, signal a drain
if (drainState() == DrainState::Draining &&
!totalWriteQueueSize && !totalReadQueueSize && allRanksDrained()) {
DPRINTF(Drain, "DRAM controller done draining\n");
// 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;
DRAMCtrl::chooseNext(DRAMPacketQueue& queue, Tick extra_col_delay)
// This method does the arbitration between requests.
DRAMCtrl::DRAMPacketQueue::iterator ret = queue.end();
if (!queue.empty()) {
if (queue.size() == 1) {
// available rank corresponds to state refresh idle
DRAMPacket* dram_pkt = *(queue.begin());
if (ranks[dram_pkt->rank]->inRefIdleState()) {
ret = queue.begin();
DPRINTF(DRAM, "Single request, going to a free rank\n");
} else {
DPRINTF(DRAM, "Single request, going to a busy rank\n");
} else if (memSchedPolicy == Enums::fcfs) {
// check if there is a packet going to a free rank
for (auto i = queue.begin(); i != queue.end(); ++i) {
DRAMPacket* dram_pkt = *i;
if (ranks[dram_pkt->rank]->inRefIdleState()) {
ret = i;
} else if (memSchedPolicy == Enums::frfcfs) {
ret = chooseNextFRFCFS(queue, extra_col_delay);
} else {
panic("No scheduling policy chosen\n");
return ret;
DRAMCtrl::chooseNextFRFCFS(DRAMPacketQueue& queue, Tick extra_col_delay)
// Only determine this if needed
vector<uint32_t> earliest_banks(ranksPerChannel, 0);
// Has minBankPrep been called to populate earliest_banks?
bool filled_earliest_banks = false;
// can the PRE/ACT sequence be done without impacting utlization?
bool hidden_bank_prep = false;
// search for seamless row hits first, if no seamless row hit is
// found then determine if there are other packets that can be issued
// without incurring additional bus delay due to bank timing
// Will select closed rows first to enable more open row possibilies
// in future selections
bool found_hidden_bank = false;
// remember if we found a row hit, not seamless, but bank prepped
// and ready
bool found_prepped_pkt = false;
// if we have no row hit, prepped or not, and no seamless packet,
// just go for the earliest possible
bool found_earliest_pkt = false;
auto selected_pkt_it = queue.end();
// time we need to issue a column command to be seamless
const Tick min_col_at = std::max(nextBurstAt + extra_col_delay, curTick());
for (auto i = queue.begin(); i != queue.end() ; ++i) {
DRAMPacket* dram_pkt = *i;
const Bank& bank = dram_pkt->bankRef;
const Tick col_allowed_at = dram_pkt->isRead() ? bank.rdAllowedAt :
DPRINTF(DRAM, "%s checking packet in bank %d\n",
__func__, dram_pkt->;
// check if rank is not doing a refresh and thus is available, if not,
// jump to the next packet
if (dram_pkt->rankRef.inRefIdleState()) {
"%s bank %d - Rank %d available\n", __func__,
dram_pkt->, dram_pkt->rankRef.rank);
// check if it is a row hit
if (bank.openRow == dram_pkt->row) {
// no additional rank-to-rank or same bank-group
// delays, or we switched read/write and might as well
// go for the row hit
if (col_allowed_at <= min_col_at) {
// FCFS within the hits, giving priority to
// commands that can issue seamlessly, without
// additional delay, such as same rank accesses
// and/or different bank-group accesses
DPRINTF(DRAM, "%s Seamless row buffer hit\n", __func__);
selected_pkt_it = i;
// no need to look through the remaining queue entries
} else if (!found_hidden_bank && !found_prepped_pkt) {
// if we did not find a packet to a closed row that can
// issue the bank commands without incurring delay, and
// did not yet find a packet to a prepped row, remember
// the current one
selected_pkt_it = i;
found_prepped_pkt = true;
DPRINTF(DRAM, "%s Prepped row buffer hit\n", __func__);
} else if (!found_earliest_pkt) {
// if we have not initialised the bank status, do it
// now, and only once per scheduling decisions
if (!filled_earliest_banks) {
// determine entries with earliest bank delay
std::tie(earliest_banks, hidden_bank_prep) =
minBankPrep(queue, min_col_at);
filled_earliest_banks = true;
// bank is amongst first available banks
// minBankPrep will give priority to packets that can
// issue seamlessly
if (bits(earliest_banks[dram_pkt->rank],
dram_pkt->bank, dram_pkt->bank)) {
found_earliest_pkt = true;
found_hidden_bank = hidden_bank_prep;
// give priority to packets that can issue
// bank commands 'behind the scenes'
// any additional delay if any will be due to
// col-to-col command requirements
if (hidden_bank_prep || !found_prepped_pkt)
selected_pkt_it = i;
} else {
DPRINTF(DRAM, "%s bank %d - Rank %d not available\n", __func__,
dram_pkt->, dram_pkt->rankRef.rank);
if (selected_pkt_it == queue.end()) {
DPRINTF(DRAM, "%s no available ranks found\n", __func__);
return selected_pkt_it;
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
// turn packet around to go back to requester if response expected
if (needsResponse) {
// access already turned the packet into a response
// response_time consumes the static latency and is charged also
// with headerDelay that takes into account the delay provided by
// the xbar and also the payloadDelay that takes into account the
// number of data beats.
Tick response_time = curTick() + static_latency + pkt->headerDelay +
// Here we reset the timing of the packet before sending it out.
pkt->headerDelay = pkt->payloadDelay = 0;
// queue the packet in the response queue to be sent out after
// the static latency has passed
port.schedTimingResp(pkt, response_time);
} else {
// @todo the packet is going to be deleted, and the DRAMPacket
// is still having a pointer to it
DPRINTF(DRAM, "Done\n");
DRAMCtrl::activateBank(Rank& rank_ref, Bank& bank_ref,
Tick act_tick, uint32_t row)
assert(rank_ref.actTicks.size() == activationLimit);
DPRINTF(DRAM, "Activate at tick %d\n", act_tick);
// update the open row
assert(bank_ref.openRow == Bank::NO_ROW);
bank_ref.openRow = row;
// start counting anew, this covers both the case when we
// auto-precharged, and when this access is forced to
// precharge
bank_ref.bytesAccessed = 0;
bank_ref.rowAccesses = 0;
assert(rank_ref.numBanksActive <= banksPerRank);
DPRINTF(DRAM, "Activate bank %d, rank %d at tick %lld, now got %d active\n",, rank_ref.rank, act_tick,
DPRINTF(DRAMPower, "%llu,ACT,%d,%d\n", divCeil(act_tick, tCK) -
timeStampOffset,, rank_ref.rank);
// The next access has to respect tRAS for this bank
bank_ref.preAllowedAt = act_tick + tRAS;
// Respect the row-to-column command delay for both read and write cmds
bank_ref.rdAllowedAt = std::max(act_tick + tRCD, bank_ref.rdAllowedAt);
bank_ref.wrAllowedAt = std::max(act_tick + tRCD, bank_ref.wrAllowedAt);
// start by enforcing tRRD
for (int i = 0; i < banksPerRank; i++) {
// next activate to any bank in this rank must not happen
// before tRRD
if (bankGroupArch && (bank_ref.bankgr == rank_ref.banks[i].bankgr)) {
// bank group architecture requires longer delays between
// ACT commands within the same bank group. Use tRRD_L
// in this case
rank_ref.banks[i].actAllowedAt = std::max(act_tick + tRRD_L,
} else {
// use shorter tRRD value when either
// 1) bank group architecture is not supportted
// 2) bank is in a different bank group
rank_ref.banks[i].actAllowedAt = std::max(act_tick + tRRD,
// next, we deal with tXAW, if the activation limit is disabled
// then we directly schedule an activate power event
if (!rank_ref.actTicks.empty()) {
// sanity check
if (rank_ref.actTicks.back() &&
(act_tick - rank_ref.actTicks.back()) < tXAW) {
panic("Got %d activates in window %d (%llu - %llu) which "
"is smaller than %llu\n", activationLimit, act_tick -
rank_ref.actTicks.back(), act_tick,
rank_ref.actTicks.back(), tXAW);
// shift the times used for the book keeping, the last element
// (highest index) is the oldest one and hence the lowest value
// record an new activation (in the future)
// 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 (rank_ref.actTicks.back() &&
(act_tick - rank_ref.actTicks.back()) < tXAW) {
DPRINTF(DRAM, "Enforcing tXAW with X = %d, next activate "
"no earlier than %llu\n", activationLimit,
rank_ref.actTicks.back() + tXAW);
for (int j = 0; j < banksPerRank; j++)
// next activate must not happen before end of window
rank_ref.banks[j].actAllowedAt =
std::max(rank_ref.actTicks.back() + tXAW,
// at the point when this activate takes place, make sure we
// transition to the active power state
if (!rank_ref.activateEvent.scheduled())
schedule(rank_ref.activateEvent, act_tick);
else if (rank_ref.activateEvent.when() > act_tick)
// move it sooner in time
reschedule(rank_ref.activateEvent, act_tick);
DRAMCtrl::prechargeBank(Rank& rank_ref, Bank& bank, Tick pre_at, bool trace)
// 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
bank.openRow = Bank::NO_ROW;
// no precharge allowed before this one
bank.preAllowedAt = pre_at;
Tick pre_done_at = pre_at + tRP;
bank.actAllowedAt = std::max(bank.actAllowedAt, pre_done_at);
assert(rank_ref.numBanksActive != 0);
DPRINTF(DRAM, "Precharging bank %d, rank %d at tick %lld, now got "
"%d active\n",, rank_ref.rank, pre_at,
if (trace) {
DPRINTF(DRAMPower, "%llu,PRE,%d,%d\n", divCeil(pre_at, tCK) -
timeStampOffset,, rank_ref.rank);
// 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 (!rank_ref.prechargeEvent.scheduled()) {
schedule(rank_ref.prechargeEvent, pre_done_at);
// New event, increment count
} else if (rank_ref.prechargeEvent.when() < pre_done_at) {
reschedule(rank_ref.prechargeEvent, pre_done_at);
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);
// get the rank
Rank& rank = dram_pkt->rankRef;
// are we in or transitioning to a low-power state and have not scheduled
// a power-up event?
// if so, wake up from power down to issue RD/WR burst
if (rank.inLowPowerState) {
assert(rank.pwrState != PWR_SREF);
// get the bank
Bank& bank = dram_pkt->bankRef;
// for the state we need to track if it is a row hit or not
bool row_hit = true;
// Determine the access latency and update the bank state
if (bank.openRow == dram_pkt->row) {
// nothing to do
} else {
row_hit = false;
// If there is a page open, precharge it.
if (bank.openRow != Bank::NO_ROW) {
prechargeBank(rank, bank, std::max(bank.preAllowedAt, curTick()));
// next we need to account for the delay in activating the
// page
Tick act_tick = std::max(bank.actAllowedAt, curTick());
// Record the activation and deal with all the global timing
// constraints caused be a new activation (tRRD and tXAW)
activateBank(rank, bank, act_tick, dram_pkt->row);
// respect any constraints on the command (e.g. tRCD or tCCD)
const Tick col_allowed_at = dram_pkt->isRead() ?
bank.rdAllowedAt : bank.wrAllowedAt;
// we need to wait until the bus is available before we can issue
// the command; need minimum of tBURST between commands
Tick cmd_at = std::max({col_allowed_at, nextBurstAt, curTick()});
// update the packet ready time
dram_pkt->readyTime = cmd_at + tCL + tBURST;
// update the time for the next read/write burst for each
// bank (add a max with tCCD/tCCD_L/tCCD_L_WR here)
Tick dly_to_rd_cmd;
Tick dly_to_wr_cmd;
for (int j = 0; j < ranksPerChannel; j++) {
for (int i = 0; i < banksPerRank; i++) {
// next burst to same bank group in this rank must not happen
// before tCCD_L. Different bank group timing requirement is
// tBURST; Add tCS for different ranks
if (dram_pkt->rank == j) {
if (bankGroupArch &&
(bank.bankgr == ranks[j]->banks[i].bankgr)) {
// bank group architecture requires longer delays between
// RD/WR burst commands to the same bank group.
// tCCD_L is default requirement for same BG timing
// tCCD_L_WR is required for write-to-write
// Need to also take bus turnaround delays into account
dly_to_rd_cmd = dram_pkt->isRead() ?
tCCD_L : std::max(tCCD_L, wrToRdDly);
dly_to_wr_cmd = dram_pkt->isRead() ?
std::max(tCCD_L, rdToWrDly) : tCCD_L_WR;
} else {
// tBURST is default requirement for diff BG timing
// Need to also take bus turnaround delays into account
dly_to_rd_cmd = dram_pkt->isRead() ? tBURST : wrToRdDly;
dly_to_wr_cmd = dram_pkt->isRead() ? rdToWrDly : tBURST;
} else {
// different rank is by default in a different bank group and
// doesn't require longer tCCD or additional RTW, WTR delays
// Need to account for rank-to-rank switching with tCS
dly_to_wr_cmd = rankToRankDly;
dly_to_rd_cmd = rankToRankDly;
ranks[j]->banks[i].rdAllowedAt = std::max(cmd_at + dly_to_rd_cmd,
ranks[j]->banks[i].wrAllowedAt = std::max(cmd_at + dly_to_wr_cmd,
// Save rank of current access
activeRank = dram_pkt->rank;
// If this is a write, we also need to respect the write recovery
// time before a precharge, in the case of a read, respect the
// read to precharge constraint
bank.preAllowedAt = std::max(bank.preAllowedAt,
dram_pkt->isRead() ? cmd_at + tRTP :
dram_pkt->readyTime + tWR);
// increment the bytes accessed and the accesses per row
bank.bytesAccessed += burstSize;
// if we reached the max, then issue with an auto-precharge
bool auto_precharge = pageMgmt == Enums::close ||
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 std::vector<DRAMPacketQueue>& queue =
dram_pkt->isRead() ? readQueue : writeQueue;
for (uint8_t i = 0; i < numPriorities(); ++i) {
auto p = queue[i].begin();
// keep on looking until we find a hit or reach the end of the queue
// 1) if a hit is found, then both open and close adaptive policies keep
// the page open
// 2) if no hit is found, got_bank_conflict is set to true if a bank
// conflict request is waiting in the queue
// 3) make sure we are not considering the packet that we are
// currently dealing with
while (!got_more_hits && p != queue[i].end()) {
if (dram_pkt != (*p)) {
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;
if (got_more_hits)
// 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);
// DRAMPower trace command to be written
std::string mem_cmd = dram_pkt->isRead() ? "RD" : "WR";
// MemCommand required for DRAMPower library
MemCommand::cmds command = (mem_cmd == "RD") ? MemCommand::RD :
// Update bus state to reflect when previous command was issued
nextBurstAt = cmd_at + tBURST;
DPRINTF(DRAM, "Access to %lld, ready at %lld next burst at %lld.\n",
dram_pkt->addr, dram_pkt->readyTime, nextBurstAt);
dram_pkt->rankRef.cmdList.push_back(Command(command, dram_pkt->bank,
DPRINTF(DRAMPower, "%llu,%s,%d,%d\n", divCeil(cmd_at, tCK) -
timeStampOffset, mem_cmd, dram_pkt->bank, dram_pkt->rank);
// if this access should use auto-precharge, then we are
// closing the row after the read/write burst
if (auto_precharge) {
// if auto-precharge push a PRE command at the correct tick to the
// list used by DRAMPower library to calculate power
prechargeBank(rank, bank, std::max(curTick(), bank.preAllowedAt));
DPRINTF(DRAM, "Auto-precharged bank: %d\n", dram_pkt->bankId);
// 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 = nextBurstAt - (tRP + tRCD);
// Update the stats and schedule the next request
if (dram_pkt->isRead()) {
if (row_hit)
stats.bytesReadDRAM += burstSize;
// Update latency stats
stats.totMemAccLat += dram_pkt->readyTime - dram_pkt->entryTime;
stats.masterReadTotalLat[dram_pkt->masterId()] +=
dram_pkt->readyTime - dram_pkt->entryTime;
stats.totBusLat += tBURST;
stats.totQLat += cmd_at - dram_pkt->entryTime;
stats.masterReadBytes[dram_pkt->masterId()] += dram_pkt->size;
} else {
if (row_hit)
stats.bytesWritten += burstSize;
stats.masterWriteBytes[dram_pkt->masterId()] += dram_pkt->size;
stats.masterWriteTotalLat[dram_pkt->masterId()] +=
dram_pkt->readyTime - dram_pkt->entryTime;
// transition is handled by QoS algorithm if enabled
if (turnPolicy) {
// select bus state - only done if QoS algorithms are in use
busStateNext = selectNextBusState();
// detect bus state change
bool switched_cmd_type = (busState != busStateNext);
// record stats
DPRINTF(DRAM, "QoS Turnarounds selected state %s %s\n",
switched_cmd_type?"[turnaround triggered]":"");
if (switched_cmd_type) {
if (busState == READ) {
"Switching to writes after %d reads with %d reads "
"waiting\n", readsThisTime, totalReadQueueSize);
readsThisTime = 0;
} else {
"Switching to reads after %d writes with %d writes "
"waiting\n", writesThisTime, totalWriteQueueSize);
writesThisTime = 0;
// updates current state
busState = busStateNext;
// check ranks for refresh/wakeup - uses busStateNext, so done after turnaround
// decisions
int busyRanks = 0;
for (auto r : ranks) {
if (!r->inRefIdleState()) {
if (r->pwrState != PWR_SREF) {
// rank is busy refreshing
DPRINTF(DRAMState, "Rank %d is not available\n", r->rank);
// let the rank know that if it was waiting to drain, it
// is now done and ready to proceed
// check if we were in self-refresh and haven't started
// to transition out
if ((r->pwrState == PWR_SREF) && r->inLowPowerState) {
DPRINTF(DRAMState, "Rank %d is in self-refresh\n", r->rank);
// if we have commands queued to this rank and we don't have
// a minimum number of active commands enqueued,
// exit self-refresh
if (r->forceSelfRefreshExit()) {
DPRINTF(DRAMState, "rank %d was in self refresh and"
" should wake up\n", r->rank);
//wake up from self-refresh
// things are brought back into action once a refresh is
// performed after self-refresh
// continue with selection for other ranks
if (busyRanks == ranksPerChannel) {
// if all ranks are refreshing wait for them to finish
// and stall this state machine without taking any further
// action, and do not schedule a new nextReqEvent
// 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 (totalReadQueueSize == 0) {
// 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 (!(totalWriteQueueSize == 0) &&
(drainState() == DrainState::Draining ||
totalWriteQueueSize > writeLowThreshold)) {
DPRINTF(DRAM, "Switching to writes due to read queue empty\n");
switch_to_writes = true;
} else {
// check if we are drained
// not done draining until in PWR_IDLE state
// ensuring all banks are closed and
// have exited low power states
if (drainState() == DrainState::Draining &&
respQueue.empty() && allRanksDrained()) {
DPRINTF(Drain, "DRAM controller done draining\n");
// nothing to do, not even any point in scheduling an
// event for the next request
} else {
bool read_found = false;
DRAMPacketQueue::iterator to_read;
uint8_t prio = numPriorities();
for (auto queue = readQueue.rbegin();
queue != readQueue.rend(); ++queue) {
"DRAM controller checking READ queue [%d] priority [%d elements]\n",
prio, queue->size());
// Figure out which read request goes next
// If we are changing command type, incorporate the minimum
// bus turnaround delay which will be tCS (different rank) case
to_read = chooseNext((*queue), switched_cmd_type ? tCS : 0);
if (to_read != queue->end()) {
// candidate read found
read_found = true;
// if no read to an available rank is found then return
// at this point. There could be writes to the available ranks
// which are above the required threshold. However, to
// avoid adding more complexity to the code, return and wait
// for a refresh event to kick things into action again.
if (!read_found) {
DPRINTF(DRAM, "No Reads Found - exiting\n");
auto dram_pkt = *to_read;
// Every respQueue which will generate an event, increment count
// sanity check
assert(dram_pkt->size <= burstSize);
assert(dram_pkt->readyTime >= curTick());
// log the response
logResponse(MemCtrl::READ, (*to_read)->masterId(),
dram_pkt->qosValue(), dram_pkt->getAddr(), 1,
dram_pkt->readyTime - dram_pkt->entryTime);
// Insert into response queue. It will be sent back to the
// requester at its readyTime
if (respQueue.empty()) {
schedule(respondEvent, dram_pkt->readyTime);
} else {
assert(respQueue.back()->readyTime <= dram_pkt->readyTime);
// we have so many writes that we have to transition
if (totalWriteQueueSize > writeHighThreshold) {
switch_to_writes = true;
// remove the request from the queue - the iterator is no longer valid .
// 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
busStateNext = WRITE;
} else {
bool write_found = false;
DRAMPacketQueue::iterator to_write;
uint8_t prio = numPriorities();
for (auto queue = writeQueue.rbegin();
queue != writeQueue.rend(); ++queue) {
"DRAM controller checking WRITE queue [%d] priority [%d elements]\n",
prio, queue->size());
// If we are changing command type, incorporate the minimum
// bus turnaround delay
to_write = chooseNext((*queue),
switched_cmd_type ? std::min(tRTW, tCS) : 0);
if (to_write != queue->end()) {
write_found = true;
// if there are no writes to a rank that is available to service
// requests (i.e. rank is in refresh idle state) are found then
// return. There could be reads to the available ranks. However, to
// avoid adding more complexity to the code, return at this point and
// wait for a refresh event to kick things into action again.
if (!write_found) {
DPRINTF(DRAM, "No Writes Found - exiting\n");
auto dram_pkt = *to_write;
// sanity check
assert(dram_pkt->size <= burstSize);
// removed write from queue, decrement count
// Schedule write done event to decrement event count
// after the readyTime has been reached
// Only schedule latest write event to minimize events
// required; only need to ensure that final event scheduled covers
// the time that writes are outstanding and bus is active
// to holdoff power-down entry events
if (!dram_pkt->rankRef.writeDoneEvent.scheduled()) {
schedule(dram_pkt->rankRef.writeDoneEvent, dram_pkt->readyTime);
// New event, increment count
} else if (dram_pkt->rankRef.writeDoneEvent.when() <
dram_pkt->readyTime) {
reschedule(dram_pkt->rankRef.writeDoneEvent, dram_pkt->readyTime);
// log the response
logResponse(MemCtrl::WRITE, dram_pkt->masterId(),
dram_pkt->qosValue(), dram_pkt->getAddr(), 1,
dram_pkt->readyTime - dram_pkt->entryTime);
// remove the request from the queue - the iterator is no longer valid
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.
bool below_threshold =
totalWriteQueueSize + minWritesPerSwitch < writeLowThreshold;
if (totalWriteQueueSize == 0 ||
(below_threshold && drainState() != DrainState::Draining) ||
(totalReadQueueSize && writesThisTime >= minWritesPerSwitch)) {
// turn the bus back around for reads again
busStateNext = 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
// It is possible that a refresh to another rank kicks things back into
// action before reaching this point.
if (!nextReqEvent.scheduled())
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 && totalWriteQueueSize < writeBufferSize) {
retryWrReq = false;
pair<vector<uint32_t>, bool>
DRAMCtrl::minBankPrep(const DRAMPacketQueue& queue,
Tick min_col_at) const
Tick min_act_at = MaxTick;
vector<uint32_t> bank_mask(ranksPerChannel, 0);
// latest Tick for which ACT can occur without incurring additoinal
// delay on the data bus
const Tick hidden_act_max = std::max(min_col_at - tRCD, curTick());
// Flag condition when burst can issue back-to-back with previous burst
bool found_seamless_bank = false;
// Flag condition when bank can be opened without incurring additional
// delay on the data bus
bool hidden_bank_prep = false;
// determine if we have queued transactions targetting the
// bank in question
vector<bool> got_waiting(ranksPerChannel * banksPerRank, false);
for (const auto& p : queue) {
if (p->rankRef.inRefIdleState())
got_waiting[p->bankId] = true;
// Find command with optimal bank timing
// Will prioritize commands that can issue seamlessly.
for (int i = 0; i < ranksPerChannel; i++) {
for (int j = 0; j < banksPerRank; j++) {
uint16_t bank_id = i * banksPerRank + j;
// if we have waiting requests for the bank, and it is
// amongst the first available, update the mask
if (got_waiting[bank_id]) {
// make sure this rank is not currently refreshing.
// simplistic approximation of when the bank can issue
// an activate, ignoring any rank-to-rank switching
// cost in this calculation
Tick act_at = ranks[i]->banks[j].openRow == Bank::NO_ROW ?
std::max(ranks[i]->banks[j].actAllowedAt, curTick()) :
std::max(ranks[i]->banks[j].preAllowedAt, curTick()) + tRP;
// When is the earliest the R/W burst can issue?
const Tick col_allowed_at = (busState == READ) ?
ranks[i]->banks[j].rdAllowedAt :
Tick col_at = std::max(col_allowed_at, act_at + tRCD);
// bank can issue burst back-to-back (seamlessly) with
// previous burst
bool new_seamless_bank = col_at <= min_col_at;
// if we found a new seamless bank or we have no
// seamless banks, and got a bank with an earlier
// activate time, it should be added to the bit mask
if (new_seamless_bank ||
(!found_seamless_bank && act_at <= min_act_at)) {
// if we did not have a seamless bank before, and
// we do now, reset the bank mask, also reset it
// if we have not yet found a seamless bank and
// the activate time is smaller than what we have
// seen so far
if (!found_seamless_bank &&
(new_seamless_bank || act_at < min_act_at)) {
std::fill(bank_mask.begin(), bank_mask.end(), 0);
found_seamless_bank |= new_seamless_bank;
// ACT can occur 'behind the scenes'
hidden_bank_prep = act_at <= hidden_act_max;
// set the bit corresponding to the available bank
replaceBits(bank_mask[i], j, j, 1);
min_act_at = act_at;
return make_pair(bank_mask, hidden_bank_prep);
DRAMCtrl::Rank::Rank(DRAMCtrl& _memory, const DRAMCtrlParams* _p, int rank)
: EventManager(&_memory), memory(_memory),
pwrStateTrans(PWR_IDLE), pwrStatePostRefresh(PWR_IDLE),
pwrStateTick(0), refreshDueAt(0), pwrState(PWR_IDLE),
refreshState(REF_IDLE), inLowPowerState(false), rank(rank),
readEntries(0), writeEntries(0), outstandingEvents(0),
wakeUpAllowedAt(0), power(_p, false), banks(_p->banks_per_rank),
numBanksActive(0), actTicks(_p->activation_limit, 0),
writeDoneEvent([this]{ processWriteDoneEvent(); }, name()),
activateEvent([this]{ processActivateEvent(); }, name()),
prechargeEvent([this]{ processPrechargeEvent(); }, name()),
refreshEvent([this]{ processRefreshEvent(); }, name()),
powerEvent([this]{ processPowerEvent(); }, name()),
wakeUpEvent([this]{ processWakeUpEvent(); }, name()),
stats(_memory, *this)
for (int b = 0; b < _p->banks_per_rank; b++) {
banks[b].bank = b;
// GDDR addressing of banks to BG is linear.
// Here we assume that all DRAM generations address bank groups as
// follows:
if (_p->bank_groups_per_rank > 0) {
// Simply assign lower bits to bank group in order to
// rotate across bank groups as banks are incremented
// e.g. with 4 banks per bank group and 16 banks total:
// banks 0,4,8,12 are in bank group 0
// banks 1,5,9,13 are in bank group 1
// banks 2,6,10,14 are in bank group 2
// banks 3,7,11,15 are in bank group 3
banks[b].bankgr = b % _p->bank_groups_per_rank;
} else {
// No bank groups; simply assign to bank number
banks[b].bankgr = b;
DRAMCtrl::Rank::startup(Tick ref_tick)
assert(ref_tick > curTick());
pwrStateTick = curTick();
// kick off the refresh, and give ourselves enough time to
// precharge
schedule(refreshEvent, ref_tick);
// Update the stats
// don't automatically transition back to LP state after next REF
pwrStatePostRefresh = PWR_IDLE;
DRAMCtrl::Rank::isQueueEmpty() const
// check commmands in Q based on current bus direction
bool no_queued_cmds = ((memory.busStateNext == READ) && (readEntries == 0))
|| ((memory.busStateNext == WRITE) &&
(writeEntries == 0));
return no_queued_cmds;
// if this rank was waiting to drain it is now able to proceed to
// precharge
if (refreshState == REF_DRAIN) {
DPRINTF(DRAM, "Refresh drain done, now precharging\n");
refreshState = REF_PD_EXIT;
// hand control back to the refresh event loop
schedule(refreshEvent, curTick());
// at the moment sort the list of commands and update the counters
// for DRAMPower libray when doing a refresh
sort(cmdList.begin(), cmdList.end(), DRAMCtrl::sortTime);
auto next_iter = cmdList.begin();
// push to commands to DRAMPower
for ( ; next_iter != cmdList.end() ; ++next_iter) {
Command cmd = *next_iter;
if (cmd.timeStamp <= curTick()) {
// Move all commands at or before curTick to DRAMPower
divCeil(cmd.timeStamp, memory.tCK) -
} else {
// done - found all commands at or before curTick()
// next_iter references the 1st command after curTick
// reset cmdList to only contain commands after curTick
// if there are no commands after curTick, updated cmdList will be empty
// in this case, next_iter is cmdList.end()
cmdList.assign(next_iter, cmdList.end());
// 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());
// counter should at least indicate one outstanding request
// for this precharge
assert(outstandingEvents > 0);
// precharge complete, decrement count
// if we reached zero, then special conditions apply as we track
// if all banks are precharged for the power models
if (numBanksActive == 0) {
// no reads to this rank in the Q and no pending
// RD/WR or refresh commands
if (isQueueEmpty() && outstandingEvents == 0 &&
memory.enableDRAMPowerdown) {
// should still be in ACT state since bank still open
assert(pwrState == PWR_ACT);
// All banks closed - switch to precharge power down state.
DPRINTF(DRAMState, "Rank %d sleep at tick %d\n",
rank, curTick());
powerDownSleep(PWR_PRE_PDN, curTick());
} else {
// we should transition to the idle state when the last bank
// is precharged
schedulePowerEvent(PWR_IDLE, curTick());
// counter should at least indicate one outstanding request
// for this write
assert(outstandingEvents > 0);
// Write transfer on bus has completed
// decrement per rank counter
// when first preparing the refresh, remember when it was due
if ((refreshState == REF_IDLE) || (refreshState == REF_SREF_EXIT)) {
// remember when the refresh is due
refreshDueAt = curTick();
// proceed to drain
refreshState = REF_DRAIN;
// make nonzero while refresh is pending to ensure
// power down and self-refresh are not entered
DPRINTF(DRAM, "Refresh due\n");
// let any scheduled read or write to the same rank go ahead,
// after which it will
// hand control back to this event loop
if (refreshState == REF_DRAIN) {
// if a request is at the moment being handled and this request is
// accessing the current rank then wait for it to finish
if ((rank == memory.activeRank)
&& (memory.nextReqEvent.scheduled())) {
// hand control over to the request loop until it is
// evaluated next
DPRINTF(DRAM, "Refresh awaiting draining\n");
} else {
refreshState = REF_PD_EXIT;
// at this point, ensure that rank is not in a power-down state
if (refreshState == REF_PD_EXIT) {
// if rank was sleeping and we have't started exit process,
// wake-up for refresh
if (inLowPowerState) {
DPRINTF(DRAM, "Wake Up for refresh\n");
// save state and return after refresh completes
} else {
refreshState = REF_PRE;
// at this point, ensure that all banks are precharged
if (refreshState == REF_PRE) {
// precharge any active bank
if (numBanksActive != 0) {
// at the moment, we use a precharge all even if there is
// only a single bank open
DPRINTF(DRAM, "Precharging all\n");
// first determine when we can precharge
Tick pre_at = curTick();
for (auto &b : banks) {
// respect both causality and any existing bank
// constraints, some banks could already have a
// (auto) precharge scheduled
pre_at = std::max(b.preAllowedAt, pre_at);
// make sure all banks per rank are precharged, and for those that
// already are, update their availability
Tick act_allowed_at = pre_at + memory.tRP;
for (auto &b : banks) {
if (b.openRow != Bank::NO_ROW) {
memory.prechargeBank(*this, b, pre_at, false);
} else {
b.actAllowedAt = std::max(b.actAllowedAt, act_allowed_at);
b.preAllowedAt = std::max(b.preAllowedAt, pre_at);
// precharge all banks in rank
cmdList.push_back(Command(MemCommand::PREA, 0, pre_at));
DPRINTF(DRAMPower, "%llu,PREA,0,%d\n",
divCeil(pre_at, memory.tCK) -
memory.timeStampOffset, rank);
} else if ((pwrState == PWR_IDLE) && (outstandingEvents == 1)) {
// Banks are closed, have transitioned to IDLE state, and
// no outstanding ACT,RD/WR,Auto-PRE sequence scheduled
DPRINTF(DRAM, "All banks already precharged, starting refresh\n");
// go ahead and kick the power state machine into gear since
// we are already idle
schedulePowerEvent(PWR_REF, curTick());
} else {
// banks state is closed but haven't transitioned pwrState to IDLE
// or have outstanding ACT,RD/WR,Auto-PRE sequence scheduled
// should have outstanding precharge event in this case
// will start refresh when pwrState transitions to IDLE
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
// last but not least we perform the actual refresh
if (refreshState == REF_START) {
// should never get here with any banks active
assert(numBanksActive == 0);
assert(pwrState == PWR_REF);
Tick ref_done_at = curTick() + memory.tRFC;
for (auto &b : banks) {
b.actAllowedAt = ref_done_at;
// at the moment this affects all ranks
cmdList.push_back(Command(MemCommand::REF, 0, curTick()));
// Update the stats
DPRINTF(DRAMPower, "%llu,REF,0,%d\n", divCeil(curTick(), memory.tCK) -
memory.timeStampOffset, rank);
// Update for next refresh
refreshDueAt += memory.tREFI;
// make sure we did not wait so long that we cannot make up
// for it
if (refreshDueAt < ref_done_at) {
fatal("Refresh was delayed so long we cannot catch up\n");
// Run the refresh and schedule event to transition power states
// when refresh completes
refreshState = REF_RUN;
schedule(refreshEvent, ref_done_at);
if (refreshState == REF_RUN) {
// should never get here with any banks active
assert(numBanksActive == 0);
assert(pwrState == PWR_REF);
if ((memory.drainState() == DrainState::Draining) ||
(memory.drainState() == DrainState::Drained)) {
// if draining, do not re-enter low-power mode.
// simply go to IDLE and wait
schedulePowerEvent(PWR_IDLE, curTick());
} else {
// At the moment, we sleep when the refresh ends and wait to be
// woken up again if previously in a low-power state.
if (pwrStatePostRefresh != PWR_IDLE) {
// power State should be power Refresh
assert(pwrState == PWR_REF);
DPRINTF(DRAMState, "Rank %d sleeping after refresh and was in "
"power state %d before refreshing\n", rank,
powerDownSleep(pwrState, curTick());
// Force PRE power-down if there are no outstanding commands
// in Q after refresh.
} else if (isQueueEmpty() && memory.enableDRAMPowerdown) {
// still have refresh event outstanding but there should
// be no other events outstanding
assert(outstandingEvents == 1);
DPRINTF(DRAMState, "Rank %d sleeping after refresh but was NOT"
" in a low power state before refreshing\n", rank);
powerDownSleep(PWR_PRE_PDN, curTick());
} else {
// 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, curTick());
// At this point, we have completed the current refresh.
// In the SREF bypass case, we do not get to this state in the
// refresh STM and therefore can always schedule next event.
// Compensate for the delay in actually performing the refresh
// when scheduling the next one
schedule(refreshEvent, refreshDueAt - memory.tRP);
DPRINTF(DRAMState, "Refresh done at %llu and next refresh"
" at %llu\n", curTick(), refreshDueAt);
DRAMCtrl::Rank::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);
DRAMCtrl::Rank::powerDownSleep(PowerState pwr_state, Tick tick)
// if low power state is active low, schedule to active low power state.
// in reality tCKE is needed to enter active low power. This is neglected
// here and could be added in the future.
if (pwr_state == PWR_ACT_PDN) {
schedulePowerEvent(pwr_state, tick);
// push command to DRAMPower
cmdList.push_back(Command(MemCommand::PDN_F_ACT, 0, tick));
DPRINTF(DRAMPower, "%llu,PDN_F_ACT,0,%d\n", divCeil(tick,
memory.tCK) - memory.timeStampOffset, rank);
} else if (pwr_state == PWR_PRE_PDN) {
// if low power state is precharge low, schedule to precharge low
// power state. In reality tCKE is needed to enter active low power.
// This is neglected here.
schedulePowerEvent(pwr_state, tick);
//push Command to DRAMPower
cmdList.push_back(Command(MemCommand::PDN_F_PRE, 0, tick));
DPRINTF(DRAMPower, "%llu,PDN_F_PRE,0,%d\n", divCeil(tick,
memory.tCK) - memory.timeStampOffset, rank);
} else if (pwr_state == PWR_REF) {
// if a refresh just occurred
// transition to PRE_PDN now that all banks are closed
// precharge power down requires tCKE to enter. For simplicity
// this is not considered.
schedulePowerEvent(PWR_PRE_PDN, tick);
//push Command to DRAMPower
cmdList.push_back(Command(MemCommand::PDN_F_PRE, 0, tick));
DPRINTF(DRAMPower, "%llu,PDN_F_PRE,0,%d\n", divCeil(tick,
memory.tCK) - memory.timeStampOffset, rank);
} else if (pwr_state == PWR_SREF) {
// should only enter SREF after PRE-PD wakeup to do a refresh
assert(pwrStatePostRefresh == PWR_PRE_PDN);
// self refresh requires time tCKESR to enter. For simplicity,
// this is not considered.
schedulePowerEvent(PWR_SREF, tick);
// push Command to DRAMPower
cmdList.push_back(Command(MemCommand::SREN, 0, tick));
DPRINTF(DRAMPower, "%llu,SREN,0,%d\n", divCeil(tick,
memory.tCK) - memory.timeStampOffset, rank);
// Ensure that we don't power-down and back up in same tick
// Once we commit to PD entry, do it and wait for at least 1tCK
// This could be replaced with tCKE if/when that is added to the model
wakeUpAllowedAt = tick + memory.tCK;
// Transitioning to a low power state, set flag
inLowPowerState = true;
DRAMCtrl::Rank::scheduleWakeUpEvent(Tick exit_delay)
Tick wake_up_tick = std::max(curTick(), wakeUpAllowedAt);
DPRINTF(DRAMState, "Scheduling wake-up for rank %d at tick %d\n",
rank, wake_up_tick);
// if waking for refresh, hold previous state
// else reset state back to IDLE
if (refreshState == REF_PD_EXIT) {
pwrStatePostRefresh = pwrState;
} else {
// don't automatically transition back to LP state after next REF
pwrStatePostRefresh = PWR_IDLE;
// schedule wake-up with event to ensure entry has completed before
// we try to wake-up
schedule(wakeUpEvent, wake_up_tick);
for (auto &b : banks) {
// respect both causality and any existing bank
// constraints, some banks could already have a
// (auto) precharge scheduled
b.wrAllowedAt = std::max(wake_up_tick + exit_delay, b.wrAllowedAt);
b.rdAllowedAt = std::max(wake_up_tick + exit_delay, b.rdAllowedAt);
b.preAllowedAt = std::max(wake_up_tick + exit_delay, b.preAllowedAt);
b.actAllowedAt = std::max(wake_up_tick + exit_delay, b.actAllowedAt);
// Transitioning out of low power state, clear flag
inLowPowerState = false;
// push to DRAMPower
// use pwrStateTrans for cases where we have a power event scheduled
// to enter low power that has not yet been processed
if (pwrStateTrans == PWR_ACT_PDN) {
cmdList.push_back(Command(MemCommand::PUP_ACT, 0, wake_up_tick));
DPRINTF(DRAMPower, "%llu,PUP_ACT,0,%d\n", divCeil(wake_up_tick,
memory.tCK) - memory.timeStampOffset, rank);
} else if (pwrStateTrans == PWR_PRE_PDN) {
cmdList.push_back(Command(MemCommand::PUP_PRE, 0, wake_up_tick));
DPRINTF(DRAMPower, "%llu,PUP_PRE,0,%d\n", divCeil(wake_up_tick,
memory.tCK) - memory.timeStampOffset, rank);
} else if (pwrStateTrans == PWR_SREF) {
cmdList.push_back(Command(MemCommand::SREX, 0, wake_up_tick));
DPRINTF(DRAMPower, "%llu,SREX,0,%d\n", divCeil(wake_up_tick,
memory.tCK) - memory.timeStampOffset, rank);
// Should be in a power-down or self-refresh state
assert((pwrState == PWR_ACT_PDN) || (pwrState == PWR_PRE_PDN) ||
(pwrState == PWR_SREF));
// Check current state to determine transition state
if (pwrState == PWR_ACT_PDN) {
// banks still open, transition to PWR_ACT
schedulePowerEvent(PWR_ACT, curTick());
} else {
// transitioning from a precharge power-down or self-refresh state
// banks are closed - transition to PWR_IDLE
schedulePowerEvent(PWR_IDLE, curTick());
assert(curTick() >= pwrStateTick);
// remember where we were, and for how long
Tick duration = curTick() - pwrStateTick;
PowerState prev_state = pwrState;
// update the accounting
stats.memoryStateTime[prev_state] += duration;
// track to total idle time
if ((prev_state == PWR_PRE_PDN) || (prev_state == PWR_ACT_PDN) ||
(prev_state == PWR_SREF)) {
stats.totalIdleTime += duration;
pwrState = pwrStateTrans;
pwrStateTick = curTick();
// if rank was refreshing, make sure to start scheduling requests again
if (prev_state == PWR_REF) {
// bus IDLED prior to REF
// counter should be one for refresh command only
assert(outstandingEvents == 1);
// REF complete, decrement count and go back to IDLE
refreshState = REF_IDLE;
DPRINTF(DRAMState, "Was refreshing for %llu ticks\n", duration);
// if moving back to power-down after refresh
if (pwrState != PWR_IDLE) {
assert(pwrState == PWR_PRE_PDN);
DPRINTF(DRAMState, "Switching to power down state after refreshing"
" rank %d at %llu tick\n", rank, curTick());
// completed refresh event, ensure next request is scheduled
if (!memory.nextReqEvent.scheduled()) {
DPRINTF(DRAM, "Scheduling next request after refreshing"
" rank %d\n", rank);
schedule(memory.nextReqEvent, curTick());
if ((pwrState == PWR_ACT) && (refreshState == REF_PD_EXIT)) {
// have exited ACT PD
assert(prev_state == PWR_ACT_PDN);
// go back to REF event and close banks
refreshState = REF_PRE;
schedule(refreshEvent, curTick());
} else if (pwrState == PWR_IDLE) {
DPRINTF(DRAMState, "All banks precharged\n");
if (prev_state == PWR_SREF) {
// set refresh state to REF_SREF_EXIT, ensuring inRefIdleState
// continues to return false during tXS after SREF exit
// Schedule a refresh which kicks things back into action
// when it finishes
refreshState = REF_SREF_EXIT;
schedule(refreshEvent, curTick() + memory.tXS);
} else {
// if we have a pending refresh, and are now moving to
// the idle state, directly transition to, or schedule refresh
if ((refreshState == REF_PRE) || (refreshState == REF_PD_EXIT)) {
// ensure refresh is restarted only after final PRE command.
// do not restart refresh if controller is in an intermediate
// state, after PRE_PDN exit, when banks are IDLE but an
// ACT is scheduled.
if (!activateEvent.scheduled()) {
// there should be nothing waiting at this point
if (refreshState == REF_PD_EXIT) {
// exiting PRE PD, will be in IDLE until tXP expires
// and then should transition to PWR_REF state
assert(prev_state == PWR_PRE_PDN);
schedulePowerEvent(PWR_REF, curTick() + memory.tXP);
} else if (refreshState == REF_PRE) {
// can directly move to PWR_REF state and proceed below
pwrState = PWR_REF;
} else {
// must have PRE scheduled to transition back to IDLE
// and re-kick off refresh
// transition to the refresh state and re-start refresh process
// refresh state machine will schedule the next power state transition
if (pwrState == PWR_REF) {
// completed final PRE for refresh or exiting power-down
assert(refreshState == REF_PRE || refreshState == REF_PD_EXIT);
// exited PRE PD for refresh, with no pending commands
// bypass auto-refresh and go straight to SREF, where memory
// will issue refresh immediately upon entry
if (pwrStatePostRefresh == PWR_PRE_PDN && isQueueEmpty() &&
(memory.drainState() != DrainState::Draining) &&
(memory.drainState() != DrainState::Drained) &&
memory.enableDRAMPowerdown) {
DPRINTF(DRAMState, "Rank %d bypassing refresh and transitioning "
"to self refresh at %11u tick\n", rank, curTick());
powerDownSleep(PWR_SREF, curTick());
// Since refresh was bypassed, remove event by decrementing count
assert(outstandingEvents == 1);
// reset state back to IDLE temporarily until SREF is entered
pwrState = PWR_IDLE;
// Not bypassing refresh for SREF entry
} else {
DPRINTF(DRAMState, "Refreshing\n");
// there should be nothing waiting at this point
// 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
schedule(refreshEvent, curTick());
// Banks transitioned to IDLE, start REF
refreshState = REF_START;
// All commands up to refresh have completed
// flush cmdList to DRAMPower
// Call the function that calculates window energy at intermediate update
// events like at refresh, stats dump as well as at simulation exit.
// Window starts at the last time the calcWindowEnergy function was called
// and is upto current time.
power.powerlib.calcWindowEnergy(divCeil(curTick(), memory.tCK) -
// Get the energy from DRAMPower
Data::MemoryPowerModel::Energy energy = power.powerlib.getEnergy();
// The energy components inside the power lib are calculated over
// the window so accumulate into the corresponding gem5 stat
stats.actEnergy += energy.act_energy * memory.devicesPerRank;
stats.preEnergy += energy.pre_energy * memory.devicesPerRank;
stats.readEnergy += energy.read_energy * memory.devicesPerRank;
stats.writeEnergy += energy.write_energy * memory.devicesPerRank;
stats.refreshEnergy += energy.ref_energy * memory.devicesPerRank;
stats.actBackEnergy += energy.act_stdby_energy * memory.devicesPerRank;
stats.preBackEnergy += energy.pre_stdby_energy * memory.devicesPerRank;
stats.actPowerDownEnergy += energy.f_act_pd_energy * memory.devicesPerRank;
stats.prePowerDownEnergy += energy.f_pre_pd_energy * memory.devicesPerRank;
stats.selfRefreshEnergy += energy.sref_energy * memory.devicesPerRank;
// Accumulate window energy into the total energy.
stats.totalEnergy += energy.window_energy * memory.devicesPerRank;
// Average power must not be accumulated but calculated over the time
// since last stats reset. SimClock::Frequency is tick period not tick
// frequency.
// energy (pJ) 1e-9
// power (mW) = ----------- * ----------
// time (tick) tick_frequency
stats.averagePower = (stats.totalEnergy.value() /
(curTick() - memory.lastStatsResetTick)) *
(SimClock::Frequency / 1000000000.0);
DPRINTF(DRAM,"Computing stats due to a dump callback\n");
// Update the stats
// final update of power state times
stats.memoryStateTime[pwrState] += (curTick() - pwrStateTick);
pwrStateTick = curTick();
DRAMCtrl::Rank::resetStats() {
// The only way to clear the counters in DRAMPower is to call
// calcWindowEnergy function as that then calls clearCounters. The
// clearCounters method itself is private.
power.powerlib.calcWindowEnergy(divCeil(curTick(), memory.tCK) -
DRAMCtrl::DRAMStats::DRAMStats(DRAMCtrl &_dram)
: Stats::Group(&_dram),
ADD_STAT(readReqs, "Number of read requests accepted"),
ADD_STAT(writeReqs, "Number of write requests accepted"),
"Number of DRAM read bursts, "
"including those serviced by the write queue"),
"Number of DRAM write bursts, "
"including those merged in the write queue"),
"Number of DRAM read bursts serviced by the write queue"),
"Number of DRAM write bursts merged with an existing one"),
"Number of requests that are neither read nor write"),
ADD_STAT(perBankRdBursts, "Per bank write bursts"),
ADD_STAT(perBankWrBursts, "Per bank write bursts"),
ADD_STAT(avgRdQLen, "Average read queue length when enqueuing"),
ADD_STAT(avgWrQLen, "Average write queue length when enqueuing"),
ADD_STAT(totQLat, "Total ticks spent queuing"),
ADD_STAT(totBusLat, "Total ticks spent in databus transfers"),
"Total ticks spent from burst creation until serviced "
"by the DRAM"),
ADD_STAT(avgQLat, "Average queueing delay per DRAM burst"),
ADD_STAT(avgBusLat, "Average bus latency per DRAM burst"),
ADD_STAT(avgMemAccLat, "Average memory access latency per DRAM burst"),
ADD_STAT(numRdRetry, "Number of times read queue was full causing retry"),
ADD_STAT(numWrRetry, "Number of times write queue was full causing retry"),
ADD_STAT(readRowHits, "Number of row buffer hits during reads"),
ADD_STAT(writeRowHits, "Number of row buffer hits during writes"),
ADD_STAT(readRowHitRate, "Row buffer hit rate for reads"),
ADD_STAT(writeRowHitRate, "Row buffer hit rate for writes"),
ADD_STAT(readPktSize, "Read request sizes (log2)"),
ADD_STAT(writePktSize, "Write request sizes (log2)"),
ADD_STAT(rdQLenPdf, "What read queue length does an incoming req see"),
ADD_STAT(wrQLenPdf, "What write queue length does an incoming req see"),
ADD_STAT(bytesPerActivate, "Bytes accessed per row activation"),
"Reads before turning the bus around for writes"),
"Writes before turning the bus around for reads"),
ADD_STAT(bytesReadDRAM, "Total number of bytes read from DRAM"),
ADD_STAT(bytesReadWrQ, "Total number of bytes read from write queue"),
ADD_STAT(bytesWritten, "Total number of bytes written to DRAM"),
ADD_STAT(bytesReadSys, "Total read bytes from the system interface side"),
"Total written bytes from the system interface side"),
ADD_STAT(avgRdBW, "Average DRAM read bandwidth in MiByte/s"),
ADD_STAT(avgWrBW, "Average achieved write bandwidth in MiByte/s"),
ADD_STAT(avgRdBWSys, "Average system read bandwidth in MiByte/s"),
ADD_STAT(avgWrBWSys, "Average system write bandwidth in MiByte/s"),
ADD_STAT(peakBW, "Theoretical peak bandwidth in MiByte/s"),
ADD_STAT(busUtil, "Data bus utilization in percentage"),
ADD_STAT(busUtilRead, "Data bus utilization in percentage for reads"),
ADD_STAT(busUtilWrite, "Data bus utilization in percentage for writes"),
ADD_STAT(totGap, "Total gap between requests"),
ADD_STAT(avgGap, "Average gap between requests"),
ADD_STAT(masterReadBytes, "Per-master bytes read from memory"),
ADD_STAT(masterWriteBytes, "Per-master bytes write to memory"),
"Per-master bytes read from memory rate (Bytes/sec)"),
"Per-master bytes write to memory rate (Bytes/sec)"),
"Per-master read serviced memory accesses"),
"Per-master write serviced memory accesses"),
"Per-master read total memory access latency"),
"Per-master write total memory access latency"),
"Per-master read average memory access latency"),
"Per-master write average memory access latency"),
ADD_STAT(pageHitRate, "Row buffer hit rate, read and write combined")
using namespace Stats;
const auto max_masters = dram._system->maxMasters();
perBankRdBursts.init(dram.banksPerRank * dram.ranksPerChannel);
perBankWrBursts.init(dram.banksPerRank * dram.ranksPerChannel);
readPktSize.init(ceilLog2(dram.burstSize) + 1);
writePktSize.init(ceilLog2(dram.burstSize) + 1);
.init(dram.maxAccessesPerRow ?
dram.maxAccessesPerRow : dram.rowBufferSize)
// per-master bytes read and written to memory
.flags(nozero | nonan);
.flags(nozero | nonan);
// per-master bytes read and written to memory rate
.flags(nozero | nonan)
.flags(nozero | nonan);
.flags(nozero | nonan)
.flags(nozero | nonan);
for (int i = 0; i < max_masters; i++) {
const std::string master = dram._system->getMasterName(i);
masterReadBytes.subname(i, master);
masterReadRate.subname(i, master);
masterWriteBytes.subname(i, master);
masterWriteRate.subname(i, master);
masterReadAccesses.subname(i, master);
masterWriteAccesses.subname(i, master);
masterReadTotalLat.subname(i, master);
masterReadAvgLat.subname(i, master);
masterWriteTotalLat.subname(i, master);
masterWriteAvgLat.subname(i, master);
// Formula stats
avgQLat = totQLat / (readBursts - servicedByWrQ);
avgBusLat = totBusLat / (readBursts - servicedByWrQ);
avgMemAccLat = totMemAccLat / (readBursts - servicedByWrQ);
readRowHitRate = (readRowHits / (readBursts - servicedByWrQ)) * 100;
writeRowHitRate = (writeRowHits / (writeBursts - mergedWrBursts)) * 100;
avgRdBW = (bytesReadDRAM / 1000000) / simSeconds;
avgWrBW = (bytesWritten / 1000000) / simSeconds;
avgRdBWSys = (bytesReadSys / 1000000) / simSeconds;
avgWrBWSys = (bytesWrittenSys / 1000000) / simSeconds;
peakBW = (SimClock::Frequency / dram.tBURST) * dram.burstSize / 1000000;
busUtil = (avgRdBW + avgWrBW) / peakBW * 100;
avgGap = totGap / (readReqs + writeReqs);
busUtilRead = avgRdBW / peakBW * 100;
busUtilWrite = avgWrBW / peakBW * 100;
pageHitRate = (writeRowHits + readRowHits) /
(writeBursts - mergedWrBursts + readBursts - servicedByWrQ) * 100;
masterReadRate = masterReadBytes / simSeconds;
masterWriteRate = masterWriteBytes / simSeconds;
masterReadAvgLat = masterReadTotalLat / masterReadAccesses;
masterWriteAvgLat = masterWriteTotalLat / masterWriteAccesses;
dram.lastStatsResetTick = curTick();
DRAMCtrl::RankStats::RankStats(DRAMCtrl &_memory, Rank &_rank)
: Stats::Group(&_memory, csprintf("rank%d", _rank.rank).c_str()),
ADD_STAT(actEnergy, "Energy for activate commands per rank (pJ)"),
ADD_STAT(preEnergy, "Energy for precharge commands per rank (pJ)"),
ADD_STAT(readEnergy, "Energy for read commands per rank (pJ)"),
ADD_STAT(writeEnergy, "Energy for write commands per rank (pJ)"),
ADD_STAT(refreshEnergy, "Energy for refresh commands per rank (pJ)"),
ADD_STAT(actBackEnergy, "Energy for active background per rank (pJ)"),
ADD_STAT(preBackEnergy, "Energy for precharge background per rank (pJ)"),
"Energy for active power-down per rank (pJ)"),
"Energy for precharge power-down per rank (pJ)"),
ADD_STAT(selfRefreshEnergy, "Energy for self refresh per rank (pJ)"),
ADD_STAT(totalEnergy, "Total energy per rank (pJ)"),
ADD_STAT(averagePower, "Core power per rank (mW)"),
ADD_STAT(totalIdleTime, "Total Idle time Per DRAM Rank"),
ADD_STAT(memoryStateTime, "Time in different power states")
memoryStateTime.subname(0, "IDLE");
memoryStateTime.subname(1, "REF");
memoryStateTime.subname(2, "SREF");
memoryStateTime.subname(3, "PRE_PDN");
memoryStateTime.subname(4, "ACT");
memoryStateTime.subname(5, "ACT_PDN");
DRAMCtrl::recvFunctional(PacketPtr pkt)
// rely on the abstract memory
Port &
DRAMCtrl::getPort(const string &if_name, PortID idx)
if (if_name != "port") {
return QoS::MemCtrl::getPort(if_name, idx);
} else {
return port;
// if there is anything in any of our internal queues, keep track
// of that as well
if (!(!totalWriteQueueSize && !totalReadQueueSize && respQueue.empty() &&
allRanksDrained())) {
DPRINTF(Drain, "DRAM controller not drained, write: %d, read: %d,"
" resp: %d\n", totalWriteQueueSize, totalReadQueueSize,
// the only queue that is not drained automatically over time
// is the write queue, thus kick things into action if needed
if (!totalWriteQueueSize && !nextReqEvent.scheduled()) {
schedule(nextReqEvent, curTick());
// also need to kick off events to exit self-refresh
for (auto r : ranks) {
// force self-refresh exit, which in turn will issue auto-refresh
if (r->pwrState == PWR_SREF) {
DPRINTF(DRAM,"Rank%d: Forcing self-refresh wakeup in drain\n",
return DrainState::Draining;
} else {
return DrainState::Drained;
DRAMCtrl::allRanksDrained() const
// true until proven false
bool all_ranks_drained = true;
for (auto r : ranks) {
// then verify that the power state is IDLE ensuring all banks are
// closed and rank is not in a low power state. Also verify that rank
// is idle from a refresh point of view.
all_ranks_drained = r->inPwrIdleState() && r->inRefIdleState() &&
return all_ranks_drained;
if (!isTimingMode && system()->isTimingMode()) {
// if we switched to timing mode, kick things into action,
// and behave as if we restored from a checkpoint
} else if (isTimingMode && !system()->isTimingMode()) {
// if we switch from timing mode, stop the refresh events to
// not cause issues with KVM
for (auto r : ranks) {
// update the mode
isTimingMode = system()->isTimingMode();
DRAMCtrl::MemoryPort::MemoryPort(const std::string& name, DRAMCtrl& _memory)
: QueuedSlavePort(name, &_memory, queue), queue(_memory, *this, true),
{ }
DRAMCtrl::MemoryPort::getAddrRanges() const
AddrRangeList ranges;
return ranges;
DRAMCtrl::MemoryPort::recvFunctional(PacketPtr pkt)
if (!queue.trySatisfyFunctional(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.
DRAMCtrl::MemoryPort::recvAtomic(PacketPtr pkt)
return memory.recvAtomic(pkt);
DRAMCtrl::MemoryPort::recvTimingReq(PacketPtr pkt)
// pass it to the memory controller
return memory.recvTimingReq(pkt);
return new DRAMCtrl(this);