dramsim2.cc

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 * Authors: Andreas Hansson
 */

#include "mem/dramsim2.hh"

#include "DRAMSim2/Callback.h"
#include "base/callback.hh"
#include "base/trace.hh"
#include "debug/DRAMSim2.hh"
#include "debug/Drain.hh"
#include "sim/system.hh"

DRAMSim2::DRAMSim2(const Params* p) :
    AbstractMemory(p),
    port(name() + ".port", *this),
    wrapper(p->deviceConfigFile, p->systemConfigFile, p->filePath,
            p->traceFile, p->range.size() / 1024 / 1024, p->enableDebug),
    retryReq(false), retryResp(false), startTick(0),
    nbrOutstandingReads(0), nbrOutstandingWrites(0),
    sendResponseEvent([this]{ sendResponse(); }, name()),
    tickEvent([this]{ tick(); }, name())
{
    DPRINTF(DRAMSim2,
            "Instantiated DRAMSim2 with clock %d ns and queue size %d\n",
            wrapper.clockPeriod(), wrapper.queueSize());

    DRAMSim::TransactionCompleteCB* read_cb =
        new DRAMSim::Callback<DRAMSim2, void, unsigned, uint64_t, uint64_t>(
            this, &DRAMSim2::readComplete);
    DRAMSim::TransactionCompleteCB* write_cb =
        new DRAMSim::Callback<DRAMSim2, void, unsigned, uint64_t, uint64_t>(
            this, &DRAMSim2::writeComplete);
    wrapper.setCallbacks(read_cb, write_cb);

    // Register a callback to compensate for the destructor not
    // being called. The callback prints the DRAMSim2 stats.
    Callback* cb = new MakeCallback<DRAMSim2Wrapper,
        &DRAMSim2Wrapper::printStats>(wrapper);
    registerExitCallback(cb);
}

void
DRAMSim2::init()
{
    AbstractMemory::init();

    if (!port.isConnected()) {
        fatal("DRAMSim2 %s is unconnected!\n", name());
    } else {
        port.sendRangeChange();
    }

    if (system()->cacheLineSize() != wrapper.burstSize())
        fatal("DRAMSim2 burst size %d does not match cache line size %d\n",
              wrapper.burstSize(), system()->cacheLineSize());
}

void
DRAMSim2::startup()
{
    startTick = curTick();

    // kick off the clock ticks
    schedule(tickEvent, clockEdge());
}

void
DRAMSim2::sendResponse()
{
    assert(!retryResp);
    assert(!responseQueue.empty());

    DPRINTF(DRAMSim2, "Attempting to send response\n");

    bool success = port.sendTimingResp(responseQueue.front());
    if (success) {
        responseQueue.pop_front();

        DPRINTF(DRAMSim2, "Have %d read, %d write, %d responses outstanding\n",
                nbrOutstandingReads, nbrOutstandingWrites,
                responseQueue.size());

        if (!responseQueue.empty() && !sendResponseEvent.scheduled())
            schedule(sendResponseEvent, curTick());

        if (nbrOutstanding() == 0)
            signalDrainDone();
    } else {
        retryResp = true;

        DPRINTF(DRAMSim2, "Waiting for response retry\n");

        assert(!sendResponseEvent.scheduled());
    }
}

unsigned int
DRAMSim2::nbrOutstanding() const
{
    return nbrOutstandingReads + nbrOutstandingWrites + responseQueue.size();
}

void
DRAMSim2::tick()
{
    wrapper.tick();

    // is the connected port waiting for a retry, if so check the
    // state and send a retry if conditions have changed
    if (retryReq && nbrOutstanding() < wrapper.queueSize()) {
        retryReq = false;
        port.sendRetryReq();
    }

    schedule(tickEvent, curTick() + wrapper.clockPeriod() * SimClock::Int::ns);
}

Tick
DRAMSim2::recvAtomic(PacketPtr pkt)
{
    access(pkt);

    // 50 ns is just an arbitrary value at this point
    return pkt->cacheResponding() ? 0 : 50000;
}

void
DRAMSim2::recvFunctional(PacketPtr pkt)
{
    pkt->pushLabel(name());

    functionalAccess(pkt);

    // potentially update the packets in our response queue as well
    for (auto i = responseQueue.begin(); i != responseQueue.end(); ++i)
        pkt->trySatisfyFunctional(*i);

    pkt->popLabel();
}

bool
DRAMSim2::recvTimingReq(PacketPtr pkt)
{
    // if a cache is responding, sink the packet without further action
    if (pkt->cacheResponding()) {
        pendingDelete.reset(pkt);
        return true;
    }

    // we should not get a new request after committing to retry the
    // current one, but unfortunately the CPU violates this rule, so
    // simply ignore it for now
    if (retryReq)
        return false;

    // if we cannot accept we need to send a retry once progress can
    // be made
    bool can_accept = nbrOutstanding() < wrapper.queueSize();

    // keep track of the transaction
    if (pkt->isRead()) {
        if (can_accept) {
            outstandingReads[pkt->getAddr()].push(pkt);

            // we count a transaction as outstanding until it has left the
            // queue in the controller, and the response has been sent
            // back, note that this will differ for reads and writes
            ++nbrOutstandingReads;
        }
    } else if (pkt->isWrite()) {
        if (can_accept) {
            outstandingWrites[pkt->getAddr()].push(pkt);

            ++nbrOutstandingWrites;

            // perform the access for writes
            accessAndRespond(pkt);
        }
    } else {
        // keep it simple and just respond if necessary
        accessAndRespond(pkt);
        return true;
    }

    if (can_accept) {
        // we should never have a situation when we think there is space,
        // and there isn't
        assert(wrapper.canAccept());

        DPRINTF(DRAMSim2, "Enqueueing address %lld\n", pkt->getAddr());

        // @todo what about the granularity here, implicit assumption that
        // a transaction matches the burst size of the memory (which we
        // cannot determine without parsing the ini file ourselves)
        wrapper.enqueue(pkt->isWrite(), pkt->getAddr());

        return true;
    } else {
        retryReq = true;
        return false;
    }
}

void
DRAMSim2::recvRespRetry()
{
    DPRINTF(DRAMSim2, "Retrying\n");

    assert(retryResp);
    retryResp = false;
    sendResponse();
}

void
DRAMSim2::accessAndRespond(PacketPtr pkt)
{
    DPRINTF(DRAMSim2, "Access for address %lld\n", 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());
        // Here we pay for xbar additional delay and to process the payload
        // of the packet.
        Tick time = curTick() + pkt->headerDelay + pkt->payloadDelay;
        // Reset the timings of the packet
        pkt->headerDelay = pkt->payloadDelay = 0;

        DPRINTF(DRAMSim2, "Queuing response for address %lld\n",
                pkt->getAddr());

        // queue it to be sent back
        responseQueue.push_back(pkt);

        // if we are not already waiting for a retry, or are scheduled
        // to send a response, schedule an event
        if (!retryResp && !sendResponseEvent.scheduled())
            schedule(sendResponseEvent, time);
    } else {
        // queue the packet for deletion
        pendingDelete.reset(pkt);
    }
}

void DRAMSim2::readComplete(unsigned id, uint64_t addr, uint64_t cycle)
{
    assert(cycle == divCeil(curTick() - startTick,
                            wrapper.clockPeriod() * SimClock::Int::ns));

    DPRINTF(DRAMSim2, "Read to address %lld complete\n", addr);

    // get the outstanding reads for the address in question
    auto p = outstandingReads.find(addr);
    assert(p != outstandingReads.end());

    // first in first out, which is not necessarily true, but it is
    // the best we can do at this point
    PacketPtr pkt = p->second.front();
    p->second.pop();

    if (p->second.empty())
        outstandingReads.erase(p);

    // no need to check for drain here as the next call will add a
    // response to the response queue straight away
    assert(nbrOutstandingReads != 0);
    --nbrOutstandingReads;

    // perform the actual memory access
    accessAndRespond(pkt);
}

void DRAMSim2::writeComplete(unsigned id, uint64_t addr, uint64_t cycle)
{
    assert(cycle == divCeil(curTick() - startTick,
                            wrapper.clockPeriod() * SimClock::Int::ns));

    DPRINTF(DRAMSim2, "Write to address %lld complete\n", addr);

    // get the outstanding reads for the address in question
    auto p = outstandingWrites.find(addr);
    assert(p != outstandingWrites.end());

    // we have already responded, and this is only to keep track of
    // what is outstanding
    p->second.pop();
    if (p->second.empty())
        outstandingWrites.erase(p);

    assert(nbrOutstandingWrites != 0);
    --nbrOutstandingWrites;

    if (nbrOutstanding() == 0)
        signalDrainDone();
}

Port &
DRAMSim2::getPort(const std::string &if_name, PortID idx)
{
    if (if_name != "port") {
        return AbstractMemory::getPort(if_name, idx);
    } else {
        return port;
    }
}

DrainState
DRAMSim2::drain()
{
    // check our outstanding reads and writes and if any they need to
    // drain
    return nbrOutstanding() != 0 ? DrainState::Draining : DrainState::Drained;
}

DRAMSim2::MemoryPort::MemoryPort(const std::string& _name,
                                 DRAMSim2& _memory)
    : SlavePort(_name, &_memory), memory(_memory)
{ }

AddrRangeList
DRAMSim2::MemoryPort::getAddrRanges() const
{
    AddrRangeList ranges;
    ranges.push_back(memory.getAddrRange());
    return ranges;
}

Tick
DRAMSim2::MemoryPort::recvAtomic(PacketPtr pkt)
{
    return memory.recvAtomic(pkt);
}

void
DRAMSim2::MemoryPort::recvFunctional(PacketPtr pkt)
{
    memory.recvFunctional(pkt);
}

bool
DRAMSim2::MemoryPort::recvTimingReq(PacketPtr pkt)
{
    // pass it to the memory controller
    return memory.recvTimingReq(pkt);
}

void
DRAMSim2::MemoryPort::recvRespRetry()
{
    memory.recvRespRetry();
}

DRAMSim2*
DRAMSim2Params::create()
{
    return new DRAMSim2(this);
}