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-rw-r--r--src/cpu/simple/timing.cc24
-rw-r--r--src/mem/bridge.cc93
-rw-r--r--src/mem/bridge.hh16
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
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-04 08:50:53 +0000