diff options
| -rw-r--r-- | src/cpu/simple/timing.cc | 24 | ||||
| -rw-r--r-- | src/mem/bridge.cc | 93 | ||||
| -rw-r--r-- | src/mem/bridge.hh | 16 |
3 files changed, 99 insertions, 34 deletions
diff --git a/src/cpu/simple/timing.cc b/src/cpu/simple/timing.cc index 45da7c3eb..fa7bb4f86 100644 --- a/src/cpu/simple/timing.cc +++ b/src/cpu/simple/timing.cc @@ -574,10 +574,16 @@ TimingSimpleCPU::IcachePort::recvTiming(PacketPtr pkt) return true; } - else { - //Snooping a Coherence Request, do nothing - return true; + else if (pkt->result == Packet::Nacked) { + assert(cpu->_status == IcacheWaitResponse); + pkt->reinitNacked(); + if (!sendTiming(pkt)) { + cpu->_status = IcacheRetry; + cpu->ifetch_pkt = pkt; + } } + //Snooping a Coherence Request, do nothing + return true; } void @@ -663,10 +669,16 @@ TimingSimpleCPU::DcachePort::recvTiming(PacketPtr pkt) return true; } - else { - //Snooping a coherence req, do nothing - return true; + else if (pkt->result == Packet::Nacked) { + assert(cpu->_status == DcacheWaitResponse); + pkt->reinitNacked(); + if (!sendTiming(pkt)) { + cpu->_status = DcacheRetry; + cpu->dcache_pkt = pkt; + } } + //Snooping a Coherence Request, do nothing + return true; } void diff --git a/src/mem/bridge.cc b/src/mem/bridge.cc index b25d135e2..e7d52b178 100644 --- a/src/mem/bridge.cc +++ b/src/mem/bridge.cc @@ -47,7 +47,8 @@ Bridge::BridgePort::BridgePort(const std::string &_name, bool fix_partial_write) : Port(_name), bridge(_bridge), otherPort(_otherPort), delay(_delay), fixPartialWrite(fix_partial_write), - outstandingResponses(0), queueLimit(_queueLimit), sendEvent(this) + outstandingResponses(0), queuedRequests(0), + queueLimit(_queueLimit), sendEvent(this) { } @@ -92,34 +93,70 @@ Bridge::init() fatal("Busses don't have the same block size... Not supported.\n"); } +bool +Bridge::BridgePort::queueFull() +{ + // use >= here because sendQueue could get larger because of + // nacks getting inserted + return queuedRequests + outstandingResponses >= queueLimit; +} /** Function called by the port when the bus is receiving a Timing * transaction.*/ bool Bridge::BridgePort::recvTiming(PacketPtr pkt) { - if (pkt->flags & SNOOP_COMMIT) { - DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n", + if (!(pkt->flags & SNOOP_COMMIT)) + return true; + + + DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n", pkt->getSrc(), pkt->getDest(), pkt->getAddr()); - return otherPort->queueForSendTiming(pkt); + if (pkt->isRequest() && otherPort->queueFull()) { + DPRINTF(BusBridge, "Remote queue full, nacking\n"); + nackRequest(pkt); + return true; } - else { - // Else it's just a snoop, properly return if we are blocking - return !queueFull(); + + if (pkt->needsResponse() && pkt->result != Packet::Nacked) + if (queueFull()) { + 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; + } + + otherPort->queueForSendTiming(pkt); + + return true; +} + +void +Bridge::BridgePort::nackRequest(PacketPtr pkt) +{ + // Nack the packet + pkt->result = Packet::Nacked; + pkt->setDest(pkt->getSrc()); + + //put it on the list to send + Tick readyTime = curTick + delay; + PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true); + if (sendQueue.empty()) { + sendEvent.schedule(readyTime); } + sendQueue.push_back(buf); } -bool +void Bridge::BridgePort::queueForSendTiming(PacketPtr pkt) { - if (queueFull()) { - DPRINTF(BusBridge, "Queue full, returning false\n"); - return false; - } - - if (pkt->isResponse()) { + if (pkt->isResponse() || pkt->result == Packet::Nacked) { // This is a response for a request we forwarded earlier. The // corresponding PacketBuffer should be stored in the packet's // senderState field. @@ -128,6 +165,13 @@ Bridge::BridgePort::queueForSendTiming(PacketPtr pkt) // set up new packet dest & senderState based on values saved // from original request buf->fixResponse(pkt); + + // Check if this packet was expecting a response (this is either it or + // its a nacked packet and we won't be seeing that response) + if (buf->expectResponse) + --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()); @@ -146,10 +190,8 @@ Bridge::BridgePort::queueForSendTiming(PacketPtr pkt) if (sendQueue.empty()) { sendEvent.schedule(readyTime); } - + ++queuedRequests; sendQueue.push_back(buf); - - return true; } void @@ -169,7 +211,8 @@ Bridge::BridgePort::trySend() pkt->flags &= ~SNOOP_COMMIT; //CLear it if it was set if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite && - pkt->getOffset(pbs) && pkt->getSize() != pbs) { + pkt->result != Packet::Nacked && pkt->getOffset(pbs) && + pkt->getSize() != pbs) { buf->partialWriteFix(this); pkt = buf->pkt; } @@ -184,10 +227,7 @@ Bridge::BridgePort::trySend() buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it if (buf->expectResponse) { - // Must wait for response. We just need to count outstanding - // responses (in case we want to cap them); PacketBuffer - // pointer will be recovered on response. - ++outstandingResponses; + // Must wait for response DPRINTF(BusBridge, " successful: awaiting response (%d)\n", outstandingResponses); } else { @@ -196,13 +236,17 @@ Bridge::BridgePort::trySend() delete buf; } + if (!buf->nacked) + --queuedRequests; + // 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)); } // Let things start sending again - if (was_full) { + if (was_full && !queueFull()) { DPRINTF(BusBridge, "Queue was full, sending retry\n"); otherPort->sendRetry(); } @@ -211,6 +255,8 @@ Bridge::BridgePort::trySend() DPRINTF(BusBridge, " unsuccessful\n"); buf->undoPartialWriteFix(); } + DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n", + sendQueue.size(), queuedRequests, outstandingResponses); } @@ -290,3 +336,4 @@ CREATE_SIM_OBJECT(Bridge) } REGISTER_SIM_OBJECT("Bridge", Bridge) + diff --git a/src/mem/bridge.hh b/src/mem/bridge.hh index d1154eda0..1fa9cdffc 100644 --- a/src/mem/bridge.hh +++ b/src/mem/bridge.hh @@ -79,13 +79,16 @@ class Bridge : public MemObject bool partialWriteFixed; PacketPtr oldPkt; + bool nacked; - PacketBuffer(PacketPtr _pkt, Tick t) + PacketBuffer(PacketPtr _pkt, Tick t, bool nack = false) : ready(t), pkt(_pkt), origSenderState(_pkt->senderState), origSrc(_pkt->getSrc()), - expectResponse(_pkt->needsResponse()), partialWriteFixed(false) + expectResponse(_pkt->needsResponse() && !nack), + partialWriteFixed(false), nacked(nack) + { - if (!pkt->isResponse()) + if (!pkt->isResponse() && !nack) pkt->senderState = this; } @@ -144,6 +147,7 @@ class Bridge : public MemObject std::list<PacketBuffer*> sendQueue; int outstandingResponses; + int queuedRequests; /** Max queue size for outbound packets */ int queueLimit; @@ -151,12 +155,14 @@ class Bridge : public MemObject /** * Is this side blocked from accepting outbound packets? */ - bool queueFull() { return (sendQueue.size() == queueLimit); } + bool queueFull(); - bool queueForSendTiming(PacketPtr pkt); + void queueForSendTiming(PacketPtr pkt); void finishSend(PacketBuffer *buf); + void nackRequest(PacketPtr pkt); + /** * Handle send event, scheduled when the packet at the head of * the outbound queue is ready to transmit (for timing |