add a backoff algorithm when nacks are received by devices

add seperate response buffers and request queue sizes in bus bridge
add delay to respond to a nack in the bus bridge

src/dev/i8254xGBe.cc:
src/dev/ide_ctrl.cc:
src/dev/ns_gige.cc:
src/dev/pcidev.hh:
src/dev/sinic.cc:
    add backoff delay parameters
src/dev/io_device.cc:
src/dev/io_device.hh:
    add a backoff algorithm when nacks are received.
src/mem/bridge.cc:
src/mem/bridge.hh:
    add seperate response buffers and request queue sizes
    add a new parameters to specify how long before a nack in ready to go after a packet that needs to be nacked is received
src/mem/cache/cache_impl.hh:
    assert on the
src/mem/tport.cc:
    add a friendly assert to make sure the packet was inserted into the list

--HG--
extra : convert_revision : 3595ad932015a4ce2bb72772da7850ad91bd09b1

1 files changed, 84 insertions, 34 deletions

diff --git a/src/mem/bridge.cc b/src/mem/bridge.cc
index e7d52b178..e89473be3 100644
--- a/src/mem/bridge.cc
+++ b/src/mem/bridge.cc
@@ -43,22 +43,22 @@
 
 Bridge::BridgePort::BridgePort(const std::string &_name,
                                Bridge *_bridge, BridgePort *_otherPort,
-                               int _delay, int _queueLimit,
-                               bool fix_partial_write)
+                               int _delay, int _nack_delay, int _req_limit,
+                               int _resp_limit, bool fix_partial_write)
     : Port(_name), bridge(_bridge), otherPort(_otherPort),
-      delay(_delay), fixPartialWrite(fix_partial_write),
-      outstandingResponses(0), queuedRequests(0),
-      queueLimit(_queueLimit), sendEvent(this)
+      delay(_delay), nackDelay(_nack_delay), fixPartialWrite(fix_partial_write),
+      outstandingResponses(0), queuedRequests(0), inRetry(false),
+      reqQueueLimit(_req_limit), respQueueLimit(_resp_limit), sendEvent(this)
 {
 }
 
-Bridge::Bridge(const std::string &n, int qsa, int qsb,
-               Tick _delay, int write_ack, bool fix_partial_write_a,
-               bool fix_partial_write_b)
-    : MemObject(n),
-      portA(n + "-portA", this, &portB, _delay, qsa, fix_partial_write_a),
-      portB(n + "-portB", this, &portA, _delay, qsa, fix_partial_write_b),
-      ackWrites(write_ack)
+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)
 {
     if (ackWrites)
         panic("No support for acknowledging writes\n");
@@ -94,11 +94,17 @@ Bridge::init()
 }
 
 bool
-Bridge::BridgePort::queueFull()
+Bridge::BridgePort::respQueueFull()
 {
-    // use >= here because sendQueue could get larger because of
-    // nacks getting inserted
-    return queuedRequests + outstandingResponses >= queueLimit;
+    assert(outstandingResponses >= 0 && outstandingResponses <= respQueueLimit);
+    return outstandingResponses >= respQueueLimit;
+}
+
+bool
+Bridge::BridgePort::reqQueueFull()
+{
+    assert(queuedRequests >= 0 && queuedRequests <= reqQueueLimit);
+    return queuedRequests >= reqQueueLimit;
 }
 
 /** Function called by the port when the bus is receiving a Timing
@@ -113,14 +119,14 @@ Bridge::BridgePort::recvTiming(PacketPtr pkt)
     DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
                 pkt->getSrc(), pkt->getDest(), pkt->getAddr());
 
-    if (pkt->isRequest() && otherPort->queueFull()) {
+    if (pkt->isRequest() && otherPort->reqQueueFull()) {
         DPRINTF(BusBridge, "Remote queue full, nacking\n");
         nackRequest(pkt);
         return true;
     }
 
     if (pkt->needsResponse() && pkt->result != Packet::Nacked)
-        if (queueFull()) {
+        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);
@@ -144,12 +150,41 @@ Bridge::BridgePort::nackRequest(PacketPtr pkt)
     pkt->setDest(pkt->getSrc());
 
     //put it on the list to send
-    Tick readyTime = curTick + delay;
+    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;
     }
-    sendQueue.push_back(buf);
+
+    assert(sendEvent.scheduled() || inRetry);
+
+    // does it go at the end?
+    if (readyTime >= sendQueue.back()->ready) {
+        sendQueue.push_back(buf);
+        return;
+    }
+
+    // ok, somewhere in the middle, fun
+    std::list<PacketBuffer*>::iterator i = sendQueue.begin();
+    std::list<PacketBuffer*>::iterator end = sendQueue.end();
+    std::list<PacketBuffer*>::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;
+        }
+        i++;
+    }
+    assert(done);
 }
 
 
@@ -199,7 +234,6 @@ Bridge::BridgePort::trySend()
 {
     assert(!sendQueue.empty());
 
-    bool was_full = queueFull();
     int pbs = peerBlockSize();
 
     PacketBuffer *buf = sendQueue.front();
@@ -245,15 +279,10 @@ Bridge::BridgePort::trySend()
             DPRINTF(BusBridge, "Scheduling next send\n");
             sendEvent.schedule(std::max(buf->ready, curTick + 1));
         }
-        // Let things start sending again
-        if (was_full && !queueFull()) {
-          DPRINTF(BusBridge, "Queue was full, sending retry\n");
-          otherPort->sendRetry();
-        }
-
     } else {
         DPRINTF(BusBridge, "  unsuccessful\n");
         buf->undoPartialWriteFix();
+        inRetry = true;
     }
     DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n",
                     sendQueue.size(), queuedRequests, outstandingResponses);
@@ -263,7 +292,12 @@ Bridge::BridgePort::trySend()
 void
 Bridge::BridgePort::recvRetry()
 {
-    trySend();
+    inRetry = false;
+    Tick nextReady = sendQueue.front()->ready;
+    if (nextReady <= curTick)
+        trySend();
+    else
+        sendEvent.schedule(nextReady);
 }
 
 /** Function called by the port when the bus is receiving a Atomic
@@ -309,9 +343,12 @@ Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp,
 
 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge)
 
-   Param<int> queue_size_a;
-   Param<int> queue_size_b;
+   Param<int> req_size_a;
+   Param<int> req_size_b;
+   Param<int> resp_size_a;
+   Param<int> resp_size_b;
    Param<Tick> delay;
+   Param<Tick> nack_delay;
    Param<bool> write_ack;
    Param<bool> fix_partial_write_a;
    Param<bool> fix_partial_write_b;
@@ -320,9 +357,12 @@ END_DECLARE_SIM_OBJECT_PARAMS(Bridge)
 
 BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge)
 
-    INIT_PARAM(queue_size_a, "The size of the queue for data coming into side a"),
-    INIT_PARAM(queue_size_b, "The size of the queue for data coming into side b"),
+    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")
@@ -331,8 +371,18 @@ END_INIT_SIM_OBJECT_PARAMS(Bridge)
 
 CREATE_SIM_OBJECT(Bridge)
 {
-    return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay,
-            write_ack, fix_partial_write_a, fix_partial_write_b);
+    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);
 }
 
 REGISTER_SIM_OBJECT("Bridge", Bridge)