X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=src%2Fmem%2Fbridge.cc;h=9c4241097ea21e33613e4641e3b1c84e00f92669;hb=e33b3aa6692b172f6db5957774a9e0289e81fa5b;hp=92beb3d7edbda9ec5b8250bc01ac87345e188a06;hpb=5e59739416bf195173f4b37ba9afb1cb8ae16566;p=gem5.git diff --git a/src/mem/bridge.cc b/src/mem/bridge.cc index 92beb3d7e..9c4241097 100644 --- a/src/mem/bridge.cc +++ b/src/mem/bridge.cc @@ -1,5 +1,16 @@ - /* + * Copyright (c) 2011-2013, 2015 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) 2006 The Regents of The University of Michigan * All rights reserved. * @@ -28,386 +39,362 @@ * * Authors: Ali Saidi * Steve Reinhardt + * Andreas Hansson */ /** * @file - * Definition of a simple bus bridge without buffering. + * Implementation of a memory-mapped bridge that connects a master + * and a slave through a request and response queue. */ -#include +#include "mem/bridge.hh" #include "base/trace.hh" -#include "mem/bridge.hh" -#include "sim/builder.hh" - -Bridge::BridgePort::BridgePort(const std::string &_name, - Bridge *_bridge, BridgePort *_otherPort, - int _delay, int _nack_delay, int _req_limit, - int _resp_limit, bool fix_partial_write) - : Port(_name), bridge(_bridge), otherPort(_otherPort), - delay(_delay), nackDelay(_nack_delay), fixPartialWrite(fix_partial_write), - outstandingResponses(0), queuedRequests(0), inRetry(false), - reqQueueLimit(_req_limit), respQueueLimit(_resp_limit), sendEvent(this) +#include "debug/Bridge.hh" +#include "params/Bridge.hh" + +Bridge::BridgeSlavePort::BridgeSlavePort(const std::string& _name, + Bridge& _bridge, + BridgeMasterPort& _masterPort, + Cycles _delay, int _resp_limit, + std::vector _ranges) + : SlavePort(_name, &_bridge), bridge(_bridge), masterPort(_masterPort), + delay(_delay), ranges(_ranges.begin(), _ranges.end()), + outstandingResponses(0), retryReq(false), respQueueLimit(_resp_limit), + sendEvent([this]{ trySendTiming(); }, _name) { } -Bridge::Bridge(Params *p) - : MemObject(p->name), - portA(p->name + "-portA", this, &portB, p->delay, p->nack_delay, - p->req_size_a, p->resp_size_a, p->fix_partial_write_a), - portB(p->name + "-portB", this, &portA, p->delay, p->nack_delay, - p->req_size_b, p->resp_size_b, p->fix_partial_write_b), - ackWrites(p->write_ack), _params(p) +Bridge::BridgeMasterPort::BridgeMasterPort(const std::string& _name, + Bridge& _bridge, + BridgeSlavePort& _slavePort, + Cycles _delay, int _req_limit) + : MasterPort(_name, &_bridge), bridge(_bridge), slavePort(_slavePort), + delay(_delay), reqQueueLimit(_req_limit), + sendEvent([this]{ trySendTiming(); }, _name) { - if (ackWrites) - panic("No support for acknowledging writes\n"); } -Port * -Bridge::getPort(const std::string &if_name, int idx) +Bridge::Bridge(Params *p) + : ClockedObject(p), + slavePort(p->name + ".slave", *this, masterPort, + ticksToCycles(p->delay), p->resp_size, p->ranges), + masterPort(p->name + ".master", *this, slavePort, + ticksToCycles(p->delay), p->req_size) { - BridgePort *port; +} - if (if_name == "side_a") - port = &portA; - else if (if_name == "side_b") - port = &portB; +Port & +Bridge::getPort(const std::string &if_name, PortID idx) +{ + if (if_name == "master") + return masterPort; + else if (if_name == "slave") + return slavePort; else - return NULL; - - if (port->getPeer() != NULL) - panic("bridge side %s already connected to.", if_name); - return port; + // pass it along to our super class + return ClockedObject::getPort(if_name, idx); } - void Bridge::init() { - // Make sure that both sides are connected to. - if (portA.getPeer() == NULL || portB.getPeer() == NULL) - fatal("Both ports of bus bridge are not connected to a bus.\n"); + // make sure both sides are connected and have the same block size + if (!slavePort.isConnected() || !masterPort.isConnected()) + fatal("Both ports of a bridge must be connected.\n"); - if (portA.peerBlockSize() != portB.peerBlockSize()) - fatal("Busses don't have the same block size... Not supported.\n"); + // notify the master side of our address ranges + slavePort.sendRangeChange(); } bool -Bridge::BridgePort::respQueueFull() +Bridge::BridgeSlavePort::respQueueFull() const { - assert(outstandingResponses >= 0 && outstandingResponses <= respQueueLimit); - return outstandingResponses >= respQueueLimit; + return outstandingResponses == respQueueLimit; } bool -Bridge::BridgePort::reqQueueFull() +Bridge::BridgeMasterPort::reqQueueFull() const { - assert(queuedRequests >= 0 && queuedRequests <= reqQueueLimit); - return queuedRequests >= reqQueueLimit; + return transmitList.size() == reqQueueLimit; } -/** Function called by the port when the bus is receiving a Timing - * transaction.*/ bool -Bridge::BridgePort::recvTiming(PacketPtr pkt) +Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt) { - DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n", - pkt->getSrc(), pkt->getDest(), pkt->getAddr()); - - DPRINTF(BusBridge, "Local queue size: %d outreq: %d outresp: %d\n", - sendQueue.size(), queuedRequests, outstandingResponses); - DPRINTF(BusBridge, "Remove queue size: %d outreq: %d outresp: %d\n", - otherPort->sendQueue.size(), otherPort->queuedRequests, - otherPort->outstandingResponses); - - if (pkt->isRequest() && otherPort->reqQueueFull() && !pkt->wasNacked()) { - DPRINTF(BusBridge, "Remote queue full, nacking\n"); - nackRequest(pkt); - return true; - } + // all checks are done when the request is accepted on the slave + // side, so we are guaranteed to have space for the response + DPRINTF(Bridge, "recvTimingResp: %s addr 0x%x\n", + pkt->cmdString(), pkt->getAddr()); - if (pkt->needsResponse() && !pkt->wasNacked()) - if (respQueueFull()) { - DPRINTF(BusBridge, "Local queue full, no space for response, nacking\n"); - DPRINTF(BusBridge, "queue size: %d outreq: %d outstanding resp: %d\n", - sendQueue.size(), queuedRequests, outstandingResponses); - nackRequest(pkt); - return true; - } else { - DPRINTF(BusBridge, "Request Needs response, reserving space\n"); - ++outstandingResponses; - } + DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size()); + + // technically the packet only reaches us after the header delay, + // and typically we also need to deserialise any payload (unless + // the two sides of the bridge are synchronous) + Tick receive_delay = pkt->headerDelay + pkt->payloadDelay; + pkt->headerDelay = pkt->payloadDelay = 0; - otherPort->queueForSendTiming(pkt); + slavePort.schedTimingResp(pkt, bridge.clockEdge(delay) + + receive_delay); return true; } -void -Bridge::BridgePort::nackRequest(PacketPtr pkt) +bool +Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt) { - // Nack the packet - pkt->setNacked(); - pkt->setDest(pkt->getSrc()); - - //put it on the list to send - Tick readyTime = curTick + nackDelay; - PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true); - - // nothing on the list, add it and we're done - if (sendQueue.empty()) { - assert(!sendEvent.scheduled()); - sendEvent.schedule(readyTime); - sendQueue.push_back(buf); - return; - } + DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n", + pkt->cmdString(), pkt->getAddr()); - assert(sendEvent.scheduled() || inRetry); + panic_if(pkt->cacheResponding(), "Should not see packets where cache " + "is responding"); - // does it go at the end? - if (readyTime >= sendQueue.back()->ready) { - sendQueue.push_back(buf); - return; - } + // 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; - // ok, somewhere in the middle, fun - std::list::iterator i = sendQueue.begin(); - std::list::iterator end = sendQueue.end(); - std::list::iterator begin = sendQueue.begin(); - bool done = false; - - while (i != end && !done) { - if (readyTime < (*i)->ready) { - if (i == begin) - sendEvent.reschedule(readyTime); - sendQueue.insert(i,buf); - done = true; + DPRINTF(Bridge, "Response queue size: %d outresp: %d\n", + transmitList.size(), outstandingResponses); + + // if the request queue is full then there is no hope + if (masterPort.reqQueueFull()) { + DPRINTF(Bridge, "Request queue full\n"); + retryReq = true; + } else { + // look at the response queue if we expect to see a response + bool expects_response = pkt->needsResponse(); + if (expects_response) { + if (respQueueFull()) { + DPRINTF(Bridge, "Response queue full\n"); + retryReq = true; + } else { + // ok to send the request with space for the response + DPRINTF(Bridge, "Reserving space for response\n"); + assert(outstandingResponses != respQueueLimit); + ++outstandingResponses; + + // no need to set retryReq to false as this is already the + // case + } + } + + if (!retryReq) { + // technically the packet only reaches us after the header + // delay, and typically we also need to deserialise any + // payload (unless the two sides of the bridge are + // synchronous) + Tick receive_delay = pkt->headerDelay + pkt->payloadDelay; + pkt->headerDelay = pkt->payloadDelay = 0; + + masterPort.schedTimingReq(pkt, bridge.clockEdge(delay) + + receive_delay); } - i++; } - assert(done); -} + // remember that we are now stalling a packet and that we have to + // tell the sending master to retry once space becomes available, + // we make no distinction whether the stalling is due to the + // request queue or response queue being full + return !retryReq; +} void -Bridge::BridgePort::queueForSendTiming(PacketPtr pkt) +Bridge::BridgeSlavePort::retryStalledReq() { - if (pkt->isResponse() || pkt->wasNacked()) { - // This is a response for a request we forwarded earlier. The - // corresponding PacketBuffer should be stored in the packet's - // senderState field. - PacketBuffer *buf = dynamic_cast(pkt->senderState); - assert(buf != NULL); - // set up new packet dest & senderState based on values saved - // from original request - buf->fixResponse(pkt); - - // Check if this packet was expecting a response and it's a nacked - // packet, in which case we will never being seeing it - if (buf->expectResponse && pkt->wasNacked()) - --outstandingResponses; - - - DPRINTF(BusBridge, "restoring sender state: %#X, from packet buffer: %#X\n", - pkt->senderState, buf); - DPRINTF(BusBridge, " is response, new dest %d\n", pkt->getDest()); - delete buf; + if (retryReq) { + DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); + retryReq = false; + sendRetryReq(); } +} - - if (pkt->isRequest() && !pkt->wasNacked()) { - ++queuedRequests; +void +Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when) +{ + // If we're about to put this packet at the head of the queue, we + // need to schedule an event to do the transmit. Otherwise there + // should already be an event scheduled for sending the head + // packet. + if (transmitList.empty()) { + bridge.schedule(sendEvent, when); } + assert(transmitList.size() != reqQueueLimit); + transmitList.emplace_back(pkt, when); +} - Tick readyTime = curTick + delay; - PacketBuffer *buf = new PacketBuffer(pkt, readyTime); - DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n", - buf->origSenderState, buf); +void +Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when) +{ // If we're about to put this packet at the head of the queue, we // need to schedule an event to do the transmit. Otherwise there // should already be an event scheduled for sending the head // packet. - if (sendQueue.empty()) { - sendEvent.schedule(readyTime); + if (transmitList.empty()) { + bridge.schedule(sendEvent, when); } - sendQueue.push_back(buf); + + transmitList.emplace_back(pkt, when); } void -Bridge::BridgePort::trySend() +Bridge::BridgeMasterPort::trySendTiming() { - assert(!sendQueue.empty()); + assert(!transmitList.empty()); + + DeferredPacket req = transmitList.front(); - PacketBuffer *buf = sendQueue.front(); + assert(req.tick <= curTick()); - assert(buf->ready <= curTick); + PacketPtr pkt = req.pkt; - PacketPtr pkt = buf->pkt; + DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n", + pkt->getAddr(), transmitList.size()); - // Ugly! @todo When multilevel coherence works this will be removed - if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite && - !pkt->wasNacked()) { - PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq, - Packet::Broadcast); - funcPkt->dataStatic(pkt->getPtr()); - sendFunctional(funcPkt); - pkt->cmd = MemCmd::WriteReq; - delete funcPkt; + if (sendTimingReq(pkt)) { + // send successful + transmitList.pop_front(); + DPRINTF(Bridge, "trySend request successful\n"); + + // If there are more packets to send, schedule event to try again. + if (!transmitList.empty()) { + DeferredPacket next_req = transmitList.front(); + DPRINTF(Bridge, "Scheduling next send\n"); + bridge.schedule(sendEvent, std::max(next_req.tick, + bridge.clockEdge())); + } + + // if we have stalled a request due to a full request queue, + // then send a retry at this point, also note that if the + // request we stalled was waiting for the response queue + // rather than the request queue we might stall it again + slavePort.retryStalledReq(); } - DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n", - buf->origSrc, pkt->getDest(), pkt->getAddr()); + // if the send failed, then we try again once we receive a retry, + // and therefore there is no need to take any action +} + +void +Bridge::BridgeSlavePort::trySendTiming() +{ + assert(!transmitList.empty()); - bool wasReq = pkt->isRequest(); - bool wasNacked = pkt->wasNacked(); + DeferredPacket resp = transmitList.front(); - if (sendTiming(pkt)) { + assert(resp.tick <= curTick()); + + PacketPtr pkt = resp.pkt; + + DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n", + pkt->getAddr(), outstandingResponses); + + if (sendTimingResp(pkt)) { // send successful - sendQueue.pop_front(); - buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it - - if (buf->expectResponse) { - // Must wait for response - DPRINTF(BusBridge, " successful: awaiting response (%d)\n", - outstandingResponses); - } else { - // no response expected... deallocate packet buffer now. - DPRINTF(BusBridge, " successful: no response expected\n"); - delete buf; - } + transmitList.pop_front(); + DPRINTF(Bridge, "trySend response successful\n"); - if (!wasNacked) { - if (wasReq) - --queuedRequests; - else - --outstandingResponses; - } + assert(outstandingResponses != 0); + --outstandingResponses; // If there are more packets to send, schedule event to try again. - if (!sendQueue.empty()) { - buf = sendQueue.front(); - DPRINTF(BusBridge, "Scheduling next send\n"); - sendEvent.schedule(std::max(buf->ready, curTick + 1)); + if (!transmitList.empty()) { + DeferredPacket next_resp = transmitList.front(); + DPRINTF(Bridge, "Scheduling next send\n"); + bridge.schedule(sendEvent, std::max(next_resp.tick, + bridge.clockEdge())); + } + + // if there is space in the request queue and we were stalling + // a request, it will definitely be possible to accept it now + // since there is guaranteed space in the response queue + if (!masterPort.reqQueueFull() && retryReq) { + DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); + retryReq = false; + sendRetryReq(); } - } else { - DPRINTF(BusBridge, " unsuccessful\n"); - inRetry = true; } - DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n", - sendQueue.size(), queuedRequests, outstandingResponses); + + // if the send failed, then we try again once we receive a retry, + // and therefore there is no need to take any action } +void +Bridge::BridgeMasterPort::recvReqRetry() +{ + trySendTiming(); +} void -Bridge::BridgePort::recvRetry() +Bridge::BridgeSlavePort::recvRespRetry() { - inRetry = false; - Tick nextReady = sendQueue.front()->ready; - if (nextReady <= curTick) - trySend(); - else - sendEvent.schedule(nextReady); + trySendTiming(); } -/** Function called by the port when the bus is receiving a Atomic - * transaction.*/ Tick -Bridge::BridgePort::recvAtomic(PacketPtr pkt) +Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) { - // fix partial atomic writes... similar to the timing code that does the - // same... will be removed once our code gets this right - if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite) { - - PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq, - Packet::Broadcast); - funcPkt->dataStatic(pkt->getPtr()); - otherPort->sendFunctional(funcPkt); - delete funcPkt; - pkt->cmd = MemCmd::WriteReq; - } - return delay + otherPort->sendAtomic(pkt); + panic_if(pkt->cacheResponding(), "Should not see packets where cache " + "is responding"); + + return delay * bridge.clockPeriod() + masterPort.sendAtomic(pkt); } -/** Function called by the port when the bus is receiving a Functional - * transaction.*/ void -Bridge::BridgePort::recvFunctional(PacketPtr pkt) +Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) { - std::list::iterator i; + pkt->pushLabel(name()); - for (i = sendQueue.begin(); i != sendQueue.end(); ++i) { - if (pkt->checkFunctional((*i)->pkt)) + // check the response queue + for (auto i = transmitList.begin(); i != transmitList.end(); ++i) { + if (pkt->trySatisfyFunctional((*i).pkt)) { + pkt->makeResponse(); return; + } + } + + // also check the master port's request queue + if (masterPort.trySatisfyFunctional(pkt)) { + return; } + pkt->popLabel(); + // fall through if pkt still not satisfied - otherPort->sendFunctional(pkt); + masterPort.sendFunctional(pkt); } -/** Function called by the port when the bus is receiving a status change.*/ -void -Bridge::BridgePort::recvStatusChange(Port::Status status) +bool +Bridge::BridgeMasterPort::trySatisfyFunctional(PacketPtr pkt) { - otherPort->sendStatusChange(status); + bool found = false; + auto i = transmitList.begin(); + + while (i != transmitList.end() && !found) { + if (pkt->trySatisfyFunctional((*i).pkt)) { + pkt->makeResponse(); + found = true; + } + ++i; + } + + return found; } -void -Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp, - bool &snoop) +AddrRangeList +Bridge::BridgeSlavePort::getAddrRanges() const { - otherPort->getPeerAddressRanges(resp, snoop); - // we don't allow snooping across bridges - snoop = false; + return ranges; } -BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge) - - Param req_size_a; - Param req_size_b; - Param resp_size_a; - Param resp_size_b; - Param delay; - Param nack_delay; - Param write_ack; - Param fix_partial_write_a; - Param fix_partial_write_b; - -END_DECLARE_SIM_OBJECT_PARAMS(Bridge) - -BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge) - - INIT_PARAM(req_size_a, "The size of the queue for requests coming into side a"), - INIT_PARAM(req_size_b, "The size of the queue for requests coming into side b"), - INIT_PARAM(resp_size_a, "The size of the queue for responses coming into side a"), - INIT_PARAM(resp_size_b, "The size of the queue for responses coming into side b"), - INIT_PARAM(delay, "The miminum delay to cross this bridge"), - INIT_PARAM(nack_delay, "The minimum delay to nack a packet"), - INIT_PARAM(write_ack, "Acknowledge any writes that are received."), - INIT_PARAM(fix_partial_write_a, "Fixup any partial block writes that are received"), - INIT_PARAM(fix_partial_write_b, "Fixup any partial block writes that are received") - -END_INIT_SIM_OBJECT_PARAMS(Bridge) - -CREATE_SIM_OBJECT(Bridge) +Bridge * +BridgeParams::create() { - Bridge::Params *p = new Bridge::Params; - p->name = getInstanceName(); - p->req_size_a = req_size_a; - p->req_size_b = req_size_b; - p->resp_size_a = resp_size_a; - p->resp_size_b = resp_size_b; - p->delay = delay; - p->nack_delay = nack_delay; - p->write_ack = write_ack; - p->fix_partial_write_a = fix_partial_write_a; - p->fix_partial_write_b = fix_partial_write_b; - return new Bridge(p); + return new Bridge(this); } - -REGISTER_SIM_OBJECT("Bridge", Bridge) - -