*/
#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&
bool
Bridge::BridgeMasterPort::reqQueueFull()
{
- return requestQueue.size() == reqQueueLimit;
+ return transmitList.size() == reqQueueLimit;
}
bool
{
// 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;
}
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
// 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
// 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
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;
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;
#define __MEM_BRIDGE_HH__
#include <list>
-#include <queue>
-#include <string>
#include "base/types.hh"
#include "mem/mem_object.hh"
-#include "mem/packet.hh"
-#include "mem/port.hh"
#include "params/Bridge.hh"
-#include "sim/eventq.hh"
/**
* A bridge is used to interface two different busses (or in general a
* The bridge comprises a slave port and a master port, that buffer
* outgoing responses and requests respectively. Buffer space is
* reserved when a request arrives, also reserving response space
- * before forwarding the request. An incoming request is always
- * accepted (recvTiming returns true), but is potentially NACKed if
- * there is no request space or response space.
+ * before forwarding the request. If there is no space present, then
+ * the bridge will delay accepting the packet until space becomes
+ * available.
*/
class Bridge : public MemObject
{
};
/**
- * A deferred request stores a packet along with its scheduled
- * transmission time, and whether we can expect to see a response
- * or not.
+ * A deferred packet stores a packet along with its scheduled
+ * transmission time
*/
- class DeferredRequest
+ class DeferredPacket
{
public:
- Tick ready;
+ Tick tick;
PacketPtr pkt;
- bool expectResponse;
- DeferredRequest(PacketPtr _pkt, Tick t)
- : ready(t), pkt(_pkt), expectResponse(_pkt->needsResponse())
- { }
- };
-
- /**
- * A deferred response stores a packet along with its scheduled
- * transmission time. It also contains information of whether the
- * bridge NACKed the packet to be able to correctly maintain
- * counters of outstanding responses.
- */
- class DeferredResponse {
-
- public:
-
- Tick ready;
- PacketPtr pkt;
- bool nackedHere;
-
- DeferredResponse(PacketPtr _pkt, Tick t, bool nack = false)
- : ready(t), pkt(_pkt), nackedHere(nack)
+ DeferredPacket(PacketPtr _pkt, Tick _tick) : tick(_tick), pkt(_pkt)
{ }
};
private:
- /** A pointer to the bridge to which this port belongs. */
- Bridge *bridge;
+ /** The bridge to which this port belongs. */
+ Bridge& bridge;
/**
- * Master port on the other side of the bridge
- * (connected to the other bus).
+ * Master port on the other side of the bridge (connected to
+ * the other bus).
*/
BridgeMasterPort& masterPort;
/** Minimum request delay though this bridge. */
Tick delay;
- /** Min delay to respond with a nack. */
- Tick nackDelay;
-
/** Address ranges to pass through the bridge */
AddrRangeList ranges;
* queue for a specified delay to model the processing delay
* of the bridge.
*/
- std::list<DeferredResponse> responseQueue;
+ std::list<DeferredPacket> transmitList;
/** Counter to track the outstanding responses. */
unsigned int outstandingResponses;
- /** If we're waiting for a retry to happen. */
- bool inRetry;
+ /** If we should send a retry when space becomes available. */
+ bool retryReq;
/** Max queue size for reserved responses. */
unsigned int respQueueLimit;
*/
bool respQueueFull();
- /**
- * Turn the request packet into a NACK response and put it in
- * the response queue and schedule its transmission.
- *
- * @param pkt the request packet to NACK
- */
- void nackRequest(PacketPtr pkt);
-
/**
* Handle send event, scheduled when the packet at the head of
* the response queue is ready to transmit (for timing
* accesses only).
*/
- void trySend();
+ void trySendTiming();
/** Send event for the response queue. */
- EventWrapper<BridgeSlavePort, &BridgeSlavePort::trySend> sendEvent;
+ EventWrapper<BridgeSlavePort,
+ &BridgeSlavePort::trySendTiming> sendEvent;
public:
* @param _bridge the structural owner
* @param _masterPort the master port on the other side of the bridge
* @param _delay the delay from seeing a response to sending it
- * @param _nack_delay the delay from a NACK to sending the response
* @param _resp_limit the size of the response queue
* @param _ranges a number of address ranges to forward
*/
- BridgeSlavePort(const std::string &_name, Bridge *_bridge,
+ BridgeSlavePort(const std::string& _name, Bridge& _bridge,
BridgeMasterPort& _masterPort, int _delay,
- int _nack_delay, int _resp_limit,
- std::vector<Range<Addr> > _ranges);
+ int _resp_limit, std::vector<Range<Addr> > _ranges);
/**
* Queue a response packet to be sent out later and also schedule
* a send if necessary.
*
* @param pkt a response to send out after a delay
+ * @param when tick when response packet should be sent
+ */
+ void schedTimingResp(PacketPtr pkt, Tick when);
+
+ /**
+ * Retry any stalled request that we have failed to accept at
+ * an earlier point in time. This call will do nothing if no
+ * request is waiting.
*/
- void queueForSendTiming(PacketPtr pkt);
+ void retryStalledReq();
protected:
/** When receiving a timing request from the peer port,
pass it to the bridge. */
- virtual bool recvTimingReq(PacketPtr pkt);
+ bool recvTimingReq(PacketPtr pkt);
/** When receiving a retry request from the peer port,
pass it to the bridge. */
- virtual void recvRetry();
+ void recvRetry();
/** When receiving a Atomic requestfrom the peer port,
pass it to the bridge. */
- virtual Tick recvAtomic(PacketPtr pkt);
+ Tick recvAtomic(PacketPtr pkt);
/** When receiving a Functional request from the peer port,
pass it to the bridge. */
- virtual void recvFunctional(PacketPtr pkt);
+ void recvFunctional(PacketPtr pkt);
/** When receiving a address range request the peer port,
pass it to the bridge. */
- virtual AddrRangeList getAddrRanges() const;
+ AddrRangeList getAddrRanges() const;
};
private:
- /** A pointer to the bridge to which this port belongs. */
- Bridge* bridge;
+ /** The bridge to which this port belongs. */
+ Bridge& bridge;
/**
- * Pointer to the slave port on the other side of the bridge
- * (connected to the other bus).
+ * The slave port on the other side of the bridge (connected
+ * to the other bus).
*/
BridgeSlavePort& slavePort;
* queue for a specified delay to model the processing delay
* of the bridge.
*/
- std::list<DeferredRequest> requestQueue;
-
- /** If we're waiting for a retry to happen. */
- bool inRetry;
+ std::list<DeferredPacket> transmitList;
/** Max queue size for request packets */
unsigned int reqQueueLimit;
* the outbound queue is ready to transmit (for timing
* accesses only).
*/
- void trySend();
+ void trySendTiming();
/** Send event for the request queue. */
- EventWrapper<BridgeMasterPort, &BridgeMasterPort::trySend> sendEvent;
+ EventWrapper<BridgeMasterPort,
+ &BridgeMasterPort::trySendTiming> sendEvent;
public:
* @param _delay the delay from seeing a request to sending it
* @param _req_limit the size of the request queue
*/
- BridgeMasterPort(const std::string &_name, Bridge *_bridge,
+ BridgeMasterPort(const std::string& _name, Bridge& _bridge,
BridgeSlavePort& _slavePort, int _delay,
int _req_limit);
* a send if necessary.
*
* @param pkt a request to send out after a delay
+ * @param when tick when response packet should be sent
*/
- void queueForSendTiming(PacketPtr pkt);
+ void schedTimingReq(PacketPtr pkt, Tick when);
/**
* Check a functional request against the packets in our
/** When receiving a timing request from the peer port,
pass it to the bridge. */
- virtual bool recvTimingResp(PacketPtr pkt);
+ bool recvTimingResp(PacketPtr pkt);
/** When receiving a retry request from the peer port,
pass it to the bridge. */
- virtual void recvRetry();
+ void recvRetry();
};
/** Slave port of the bridge. */
/** Master port of the bridge. */
BridgeMasterPort masterPort;
- /** If this bridge should acknowledge writes. */
- bool ackWrites;
-
public:
- typedef BridgeParams Params;
-
- protected:
- Params *_params;
-
- public:
- const Params *params() const { return _params; }
virtual MasterPort& getMasterPort(const std::string& if_name,
int idx = -1);
virtual void init();
+ typedef BridgeParams Params;
+
Bridge(Params *p);
};
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