diff options
Diffstat (limited to 'src/mem')
| -rw-r--r-- | src/mem/SimpleDRAM.py | 4 | ||||
| -rw-r--r-- | src/mem/simple_dram.cc | 53 |
2 files changed, 49 insertions, 8 deletions
diff --git a/src/mem/SimpleDRAM.py b/src/mem/SimpleDRAM.py index c450f8992..b16aa6003 100644 --- a/src/mem/SimpleDRAM.py +++ b/src/mem/SimpleDRAM.py @@ -53,8 +53,8 @@ class MemSched(Enum): vals = ['fcfs', 'frfcfs'] # open row. For a closed-page policy, CoRaBaCh maximises parallelism. class AddrMap(Enum): vals = ['RaBaChCo', 'RaBaCoCh', 'CoRaBaCh'] -# Enum for the page policy, either open or close. -class PageManage(Enum): vals = ['open', 'close'] +# Enum for the page policy, either open, open_adaptive or close. +class PageManage(Enum): vals = ['open', 'open_adaptive', 'close'] # SimpleDRAM is a single-channel single-ported DRAM controller model # that aims to model the most important system-level performance diff --git a/src/mem/simple_dram.cc b/src/mem/simple_dram.cc index 2d46b8522..69209fb8a 100644 --- a/src/mem/simple_dram.cc +++ b/src/mem/simple_dram.cc @@ -598,7 +598,8 @@ SimpleDRAM::printParams() const string scheduler = memSchedPolicy == Enums::fcfs ? "FCFS" : "FR-FCFS"; string address_mapping = addrMapping == Enums::RaBaChCo ? "RaBaChCo" : (addrMapping == Enums::RaBaCoCh ? "RaBaCoCh" : "CoRaBaCh"); - string page_policy = pageMgmt == Enums::open ? "OPEN" : "CLOSE"; + string page_policy = pageMgmt == Enums::open ? "OPEN" : + (pageMgmt == Enums::open_adaptive ? "OPEN (adaptive)" : "CLOSE"); DPRINTF(DRAM, "Memory controller %s characteristics\n" \ @@ -924,7 +925,8 @@ SimpleDRAM::estimateLatency(DRAMPacket* dram_pkt, Tick inTime) Tick potentialActTick; const Bank& bank = dram_pkt->bankRef; - if (pageMgmt == Enums::open) { // open-page policy + // open-page policy + if (pageMgmt == Enums::open || pageMgmt == Enums::open_adaptive) { if (bank.openRow == dram_pkt->row) { // When we have a row-buffer hit, // we don't care about tRAS having expired or not, @@ -955,13 +957,17 @@ SimpleDRAM::estimateLatency(DRAMPacket* dram_pkt, Tick inTime) 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 == -1 ? 0 : tRP; + //The bank is free, and you may be able to activate - potentialActTick = inTime + accLat + tRP; + potentialActTick = inTime + accLat + precharge_delay; if (potentialActTick < bank.actAllowedAt) accLat += bank.actAllowedAt - potentialActTick; - accLat += tRP + tRCD + tCL; - bankLat += tRP + tRCD + tCL; + accLat += precharge_delay + tRCD + tCL; + bankLat += precharge_delay + tRCD + tCL; } } else if (pageMgmt == Enums::close) { // With a close page policy, no notion of @@ -1067,7 +1073,7 @@ SimpleDRAM::doDRAMAccess(DRAMPacket* dram_pkt) Bank& bank = dram_pkt->bankRef; // Update bank state - if (pageMgmt == Enums::open) { + if (pageMgmt == Enums::open || pageMgmt == Enums::open_adaptive) { bank.openRow = dram_pkt->row; bank.freeAt = curTick() + addDelay + accessLat; bank.bytesAccessed += burstSize; @@ -1085,6 +1091,41 @@ SimpleDRAM::doDRAMAccess(DRAMPacket* dram_pkt) bytesPerActivate.sample(bank.bytesAccessed); bank.bytesAccessed = 0; } + + if (pageMgmt == Enums::open_adaptive) { + // a twist on the open page policy is to not blindly keep the + // page open, but close it if there are no row hits, and there + // are bank conflicts in the queue + bool got_more_hits = false; + bool got_bank_conflict = false; + + // either look at the read queue or write queue + const deque<DRAMPacket*>& 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 both or reached + // the end + while (!(got_more_hits && got_bank_conflict) && + 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 + if (!got_more_hits && got_bank_conflict) { + bank.openRow = -1; + bank.freeAt = std::max(bank.freeAt, bank.tRASDoneAt) + tRP; + } + } + DPRINTF(DRAM, "doDRAMAccess::bank.freeAt is %lld\n", bank.freeAt); } else if (pageMgmt == Enums::close) { actTick = curTick() + addDelay + accessLat - tRCD - tCL; |