diff options
Diffstat (limited to 'src/mem/bridge.cc')
| -rw-r--r-- | src/mem/bridge.cc | 268 |
1 files changed, 112 insertions, 156 deletions
diff --git a/src/mem/bridge.cc b/src/mem/bridge.cc index e9dc68a03..ca3fde0ed 100644 --- a/src/mem/bridge.cc +++ b/src/mem/bridge.cc @@ -49,43 +49,37 @@ */ #include "base/trace.hh" -#include "debug/BusBridge.hh" +#include "debug/Bridge.hh" #include "mem/bridge.hh" #include "params/Bridge.hh" -Bridge::BridgeSlavePort::BridgeSlavePort(const std::string &_name, - Bridge* _bridge, +Bridge::BridgeSlavePort::BridgeSlavePort(const std::string& _name, + Bridge& _bridge, BridgeMasterPort& _masterPort, - int _delay, int _nack_delay, - int _resp_limit, + int _delay, int _resp_limit, std::vector<Range<Addr> > _ranges) - : SlavePort(_name, _bridge), bridge(_bridge), masterPort(_masterPort), - delay(_delay), nackDelay(_nack_delay), - ranges(_ranges.begin(), _ranges.end()), - outstandingResponses(0), inRetry(false), + : SlavePort(_name, &_bridge), bridge(_bridge), masterPort(_masterPort), + delay(_delay), ranges(_ranges.begin(), _ranges.end()), + outstandingResponses(0), retryReq(false), respQueueLimit(_resp_limit), sendEvent(*this) { } -Bridge::BridgeMasterPort::BridgeMasterPort(const std::string &_name, - Bridge* _bridge, +Bridge::BridgeMasterPort::BridgeMasterPort(const std::string& _name, + Bridge& _bridge, BridgeSlavePort& _slavePort, int _delay, int _req_limit) - : MasterPort(_name, _bridge), bridge(_bridge), slavePort(_slavePort), - delay(_delay), inRetry(false), reqQueueLimit(_req_limit), - sendEvent(*this) + : MasterPort(_name, &_bridge), bridge(_bridge), slavePort(_slavePort), + delay(_delay), reqQueueLimit(_req_limit), sendEvent(*this) { } Bridge::Bridge(Params *p) : MemObject(p), - slavePort(p->name + ".slave", this, masterPort, p->delay, - p->nack_delay, p->resp_size, p->ranges), - masterPort(p->name + ".master", this, slavePort, p->delay, p->req_size), - ackWrites(p->write_ack), _params(p) + slavePort(p->name + ".slave", *this, masterPort, p->delay, p->resp_size, + p->ranges), + masterPort(p->name + ".master", *this, slavePort, p->delay, p->req_size) { - if (ackWrites) - panic("No support for acknowledging writes\n"); } MasterPort& @@ -133,7 +127,7 @@ Bridge::BridgeSlavePort::respQueueFull() bool Bridge::BridgeMasterPort::reqQueueFull() { - return requestQueue.size() == reqQueueLimit; + return transmitList.size() == reqQueueLimit; } bool @@ -141,12 +135,12 @@ Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt) { // all checks are done when the request is accepted on the slave // side, so we are guaranteed to have space for the response - DPRINTF(BusBridge, "recvTiming: response %s addr 0x%x\n", + DPRINTF(Bridge, "recvTimingResp: %s addr 0x%x\n", pkt->cmdString(), pkt->getAddr()); - DPRINTF(BusBridge, "Request queue size: %d\n", requestQueue.size()); + DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size()); - slavePort.queueForSendTiming(pkt); + slavePort.schedTimingResp(pkt, curTick() + delay); return true; } @@ -154,95 +148,52 @@ Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt) bool Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt) { - DPRINTF(BusBridge, "recvTiming: request %s addr 0x%x\n", + DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n", pkt->cmdString(), pkt->getAddr()); - DPRINTF(BusBridge, "Response queue size: %d outresp: %d\n", - responseQueue.size(), outstandingResponses); + // ensure we do not have something waiting to retry + if(retryReq) + return false; - if (masterPort.reqQueueFull()) { - DPRINTF(BusBridge, "Request queue full, nacking\n"); - nackRequest(pkt); - return true; - } + DPRINTF(Bridge, "Response queue size: %d outresp: %d\n", + transmitList.size(), outstandingResponses); - if (pkt->needsResponse()) { + if (masterPort.reqQueueFull()) { + DPRINTF(Bridge, "Request queue full\n"); + retryReq = true; + } else if (pkt->needsResponse()) { if (respQueueFull()) { - DPRINTF(BusBridge, - "Response queue full, no space for response, nacking\n"); - DPRINTF(BusBridge, - "queue size: %d outstanding resp: %d\n", - responseQueue.size(), outstandingResponses); - nackRequest(pkt); - return true; + DPRINTF(Bridge, "Response queue full\n"); + retryReq = true; } else { - DPRINTF(BusBridge, "Request Needs response, reserving space\n"); + DPRINTF(Bridge, "Reserving space for response\n"); assert(outstandingResponses != respQueueLimit); ++outstandingResponses; + retryReq = false; + masterPort.schedTimingReq(pkt, curTick() + delay); } } - masterPort.queueForSendTiming(pkt); - - return true; + // 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::BridgeSlavePort::nackRequest(PacketPtr pkt) +Bridge::BridgeSlavePort::retryStalledReq() { - // Nack the packet - pkt->makeTimingResponse(); - pkt->setNacked(); - - // The Nack packets are stored in the response queue just like any - // other response, but they do not occupy any space as this is - // tracked by the outstandingResponses, this guarantees space for - // the Nack packets, but implicitly means we have an (unrealistic) - // unbounded Nack queue. - - // put it on the list to send - Tick readyTime = curTick() + nackDelay; - DeferredResponse resp(pkt, readyTime, true); - - // nothing on the list, add it and we're done - if (responseQueue.empty()) { - assert(!sendEvent.scheduled()); - bridge->schedule(sendEvent, readyTime); - responseQueue.push_back(resp); - return; + if (retryReq) { + DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); + retryReq = false; + sendRetry(); } - - assert(sendEvent.scheduled() || inRetry); - - // does it go at the end? - if (readyTime >= responseQueue.back().ready) { - responseQueue.push_back(resp); - return; - } - - // ok, somewhere in the middle, fun - std::list<DeferredResponse>::iterator i = responseQueue.begin(); - std::list<DeferredResponse>::iterator end = responseQueue.end(); - std::list<DeferredResponse>::iterator begin = responseQueue.begin(); - bool done = false; - - while (i != end && !done) { - if (readyTime < (*i).ready) { - if (i == begin) - bridge->reschedule(sendEvent, readyTime); - responseQueue.insert(i, resp); - done = true; - } - i++; - } - assert(done); } void -Bridge::BridgeMasterPort::queueForSendTiming(PacketPtr pkt) +Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when) { - Tick readyTime = curTick() + delay; - // If we expect to see a response, we need to restore the source // and destination field that is potentially changed by a second // bus @@ -257,18 +208,18 @@ Bridge::BridgeMasterPort::queueForSendTiming(PacketPtr pkt) // need to schedule an event to do the transmit. Otherwise there // should already be an event scheduled for sending the head // packet. - if (requestQueue.empty()) { - bridge->schedule(sendEvent, readyTime); + if (transmitList.empty()) { + bridge.schedule(sendEvent, when); } - assert(requestQueue.size() != reqQueueLimit); + assert(transmitList.size() != reqQueueLimit); - requestQueue.push_back(DeferredRequest(pkt, readyTime)); + transmitList.push_back(DeferredPacket(pkt, when)); } void -Bridge::BridgeSlavePort::queueForSendTiming(PacketPtr pkt) +Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when) { // This is a response for a request we forwarded earlier. The // corresponding request state should be stored in the packet's @@ -278,119 +229,124 @@ Bridge::BridgeSlavePort::queueForSendTiming(PacketPtr pkt) // set up new packet dest & senderState based on values saved // from original request req_state->fixResponse(pkt); + delete req_state; // the bridge assumes that at least one bus has set the // destination field of the packet assert(pkt->isDestValid()); - DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest()); - delete req_state; - - Tick readyTime = curTick() + delay; + DPRINTF(Bridge, "response, new dest %d\n", pkt->getDest()); // 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 (responseQueue.empty()) { - bridge->schedule(sendEvent, readyTime); + if (transmitList.empty()) { + bridge.schedule(sendEvent, when); } - responseQueue.push_back(DeferredResponse(pkt, readyTime)); + + transmitList.push_back(DeferredPacket(pkt, when)); } void -Bridge::BridgeMasterPort::trySend() +Bridge::BridgeMasterPort::trySendTiming() { - assert(!requestQueue.empty()); + assert(!transmitList.empty()); - DeferredRequest req = requestQueue.front(); + DeferredPacket req = transmitList.front(); - assert(req.ready <= curTick()); + assert(req.tick <= curTick()); PacketPtr pkt = req.pkt; - DPRINTF(BusBridge, "trySend request: addr 0x%x\n", pkt->getAddr()); + DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n", + pkt->getAddr(), transmitList.size()); if (sendTimingReq(pkt)) { // send successful - requestQueue.pop_front(); + transmitList.pop_front(); + DPRINTF(Bridge, "trySend request successful\n"); // If there are more packets to send, schedule event to try again. - if (!requestQueue.empty()) { - req = requestQueue.front(); - DPRINTF(BusBridge, "Scheduling next send\n"); - bridge->schedule(sendEvent, - std::max(req.ready, curTick() + 1)); + if (!transmitList.empty()) { + req = transmitList.front(); + DPRINTF(Bridge, "Scheduling next send\n"); + bridge.schedule(sendEvent, std::max(req.tick, + bridge.nextCycle())); } - } else { - inRetry = true; + + // 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: request queue size: %d\n", - requestQueue.size()); + // 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::trySend() +Bridge::BridgeSlavePort::trySendTiming() { - assert(!responseQueue.empty()); + assert(!transmitList.empty()); - DeferredResponse resp = responseQueue.front(); + DeferredPacket resp = transmitList.front(); - assert(resp.ready <= curTick()); + assert(resp.tick <= curTick()); PacketPtr pkt = resp.pkt; - DPRINTF(BusBridge, "trySend response: dest %d addr 0x%x\n", - pkt->getDest(), pkt->getAddr()); - - bool was_nacked_here = resp.nackedHere; + DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n", + pkt->getAddr(), outstandingResponses); if (sendTimingResp(pkt)) { - DPRINTF(BusBridge, " successful\n"); // send successful - responseQueue.pop_front(); + transmitList.pop_front(); + DPRINTF(Bridge, "trySend response successful\n"); - if (!was_nacked_here) { - assert(outstandingResponses != 0); - --outstandingResponses; - } + assert(outstandingResponses != 0); + --outstandingResponses; // If there are more packets to send, schedule event to try again. - if (!responseQueue.empty()) { - resp = responseQueue.front(); - DPRINTF(BusBridge, "Scheduling next send\n"); - bridge->schedule(sendEvent, - std::max(resp.ready, curTick() + 1)); + if (!transmitList.empty()) { + resp = transmitList.front(); + DPRINTF(Bridge, "Scheduling next send\n"); + bridge.schedule(sendEvent, std::max(resp.tick, + bridge.nextCycle())); + } + + // 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; + sendRetry(); } - } else { - DPRINTF(BusBridge, " unsuccessful\n"); - inRetry = true; } - DPRINTF(BusBridge, "trySend: queue size: %d outstanding resp: %d\n", - responseQueue.size(), 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::recvRetry() { - inRetry = false; - Tick nextReady = requestQueue.front().ready; + Tick nextReady = transmitList.front().tick; if (nextReady <= curTick()) - trySend(); + trySendTiming(); else - bridge->schedule(sendEvent, nextReady); + bridge.schedule(sendEvent, nextReady); } void Bridge::BridgeSlavePort::recvRetry() { - inRetry = false; - Tick nextReady = responseQueue.front().ready; + Tick nextReady = transmitList.front().tick; if (nextReady <= curTick()) - trySend(); + trySendTiming(); else - bridge->schedule(sendEvent, nextReady); + bridge.schedule(sendEvent, nextReady); } Tick @@ -402,12 +358,12 @@ Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) void Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) { - std::list<DeferredResponse>::iterator i; + std::list<DeferredPacket>::iterator i; pkt->pushLabel(name()); // check the response queue - for (i = responseQueue.begin(); i != responseQueue.end(); ++i) { + for (i = transmitList.begin(); i != transmitList.end(); ++i) { if (pkt->checkFunctional((*i).pkt)) { pkt->makeResponse(); return; @@ -429,9 +385,9 @@ bool Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt) { bool found = false; - std::list<DeferredRequest>::iterator i = requestQueue.begin(); + std::list<DeferredPacket>::iterator i = transmitList.begin(); - while(i != requestQueue.end() && !found) { + while(i != transmitList.end() && !found) { if (pkt->checkFunctional((*i).pkt)) { pkt->makeResponse(); found = true; |