dramsim3.cc

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#include "mem/dramsim3.hh"
 
#include "base/callback.hh"
#include "base/trace.hh"
#include "debug/DRAMsim3.hh"
#include "debug/Drain.hh"
#include "sim/system.hh"
 
namespace gem5
{
 
namespace memory
{
 
DRAMsim3::DRAMsim3(const Params &p) :
    AbstractMemory(p),
    port(name() + ".port", *this),
    read_cb(std::bind(&DRAMsim3::readComplete,
                      this, 0, std::placeholders::_1)),
    write_cb(std::bind(&DRAMsim3::writeComplete,
                       this, 0, std::placeholders::_1)),
    wrapper(p.configFile, p.filePath, read_cb, write_cb),
    retryReq(false), retryResp(false), startTick(0),
    nbrOutstandingReads(0), nbrOutstandingWrites(0),
    sendResponseEvent([this]{ sendResponse(); }, name()),
    tickEvent([this]{ tick(); }, name())
{
    DPRINTF(DRAMsim3,
            "Instantiated DRAMsim3 with clock %d ns and queue size %d\n",
            wrapper.clockPeriod(), wrapper.queueSize());
 
    // Register a callback to compensate for the destructor not
    // being called. The callback prints the DRAMsim3 stats.
    registerExitCallback([this]() { wrapper.printStats(); });
}
 
void
DRAMsim3::init()
{
    AbstractMemory::init();
 
    if (!port.isConnected()) {
        fatal("DRAMsim3 %s is unconnected!\n", name());
    } else {
        port.sendRangeChange();
    }
 
    if (system()->cacheLineSize() != wrapper.burstSize())
        fatal("DRAMsim3 burst size %d does not match cache line size %d\n",
              wrapper.burstSize(), system()->cacheLineSize());
}
 
void
DRAMsim3::startup()
{
    startTick = curTick();
 
    // kick off the clock ticks
    schedule(tickEvent, clockEdge());
}
 
void
DRAMsim3::resetStats() {
    wrapper.resetStats();
}
 
void
DRAMsim3::sendResponse()
{
    assert(!retryResp);
    assert(!responseQueue.empty());
 
    DPRINTF(DRAMsim3, "Attempting to send response\n");
 
    bool success = port.sendTimingResp(responseQueue.front());
    if (success) {
        responseQueue.pop_front();
 
        DPRINTF(DRAMsim3, "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(DRAMsim3, "Waiting for response retry\n");
 
        assert(!sendResponseEvent.scheduled());
    }
}
 
unsigned int
DRAMsim3::nbrOutstanding() const
{
    return nbrOutstandingReads + nbrOutstandingWrites + responseQueue.size();
}
 
void
DRAMsim3::tick()
{
    // Only tick when it's timing mode
    if (system()->isTimingMode()) {
        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() * sim_clock::as_int::ns);
}
 
Tick
DRAMsim3::recvAtomic(PacketPtr pkt)
{
    access(pkt);
 
    // 50 ns is just an arbitrary value at this point
    return pkt->cacheResponding() ? 0 : 50000;
}
 
void
DRAMsim3::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
DRAMsim3::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(pkt->getAddr(), pkt->isWrite()));
 
        DPRINTF(DRAMsim3, "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->getAddr(), pkt->isWrite());
 
        return true;
    } else {
        retryReq = true;
        return false;
    }
}
 
void
DRAMsim3::recvRespRetry()
{
    DPRINTF(DRAMsim3, "Retrying\n");
 
    assert(retryResp);
    retryResp = false;
    sendResponse();
}
 
void
DRAMsim3::accessAndRespond(PacketPtr pkt)
{
    DPRINTF(DRAMsim3, "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 requestor 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(DRAMsim3, "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 DRAMsim3::readComplete(unsigned id, uint64_t addr)
{
 
    DPRINTF(DRAMsim3, "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 DRAMsim3::writeComplete(unsigned id, uint64_t addr)
{
 
    DPRINTF(DRAMsim3, "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&
DRAMsim3::getPort(const std::string &if_name, PortID idx)
{
    if (if_name != "port") {
        return ClockedObject::getPort(if_name, idx);
    } else {
        return port;
    }
}
 
DrainState
DRAMsim3::drain()
{
    // check our outstanding reads and writes and if any they need to
    // drain
    return nbrOutstanding() != 0 ? DrainState::Draining : DrainState::Drained;
}
 
DRAMsim3::MemoryPort::MemoryPort(const std::string& _name,
                                 DRAMsim3& _memory)
    : ResponsePort(_name), mem(_memory)
{ }
 
AddrRangeList
DRAMsim3::MemoryPort::getAddrRanges() const
{
    AddrRangeList ranges;
    ranges.push_back(mem.getAddrRange());
    return ranges;
}
 
Tick
DRAMsim3::MemoryPort::recvAtomic(PacketPtr pkt)
{
    return mem.recvAtomic(pkt);
}
 
void
DRAMsim3::MemoryPort::recvFunctional(PacketPtr pkt)
{
    mem.recvFunctional(pkt);
}
 
bool
DRAMsim3::MemoryPort::recvTimingReq(PacketPtr pkt)
{
    // pass it to the memory controller
    return mem.recvTimingReq(pkt);
}
 
void
DRAMsim3::MemoryPort::recvRespRetry()
{
    mem.recvRespRetry();
}
 
} // namespace memory
} // namespace gem5