Add a very poor implementation of dealing with retries on timing requests. It is especially slow with tracing on since

it ends up being O(N^2). But it's probably going to have to change for the real bus anyway, so it should be rewritten then
Change recvRetry() to not accept a packet. Sendtiming should be called again (and can respond with false or true)
Removed Port Blocked/Unblocked and replaced with sendRetry().
Remove possibility of packet mangling if packet is going to be refused anyway in bridge

src/cpu/simple/atomic.cc:
src/cpu/simple/atomic.hh:
src/cpu/simple/timing.cc:
src/cpu/simple/timing.hh:
    Change recvRetry() to not accept a packet. Sendtiming should be called again (and can respond with false or true)
src/dev/io_device.cc:
src/dev/io_device.hh:
    Make DMA Timing requests/responses work.
    Change recvRetry() to not accept a packet. Sendtiming should be called again (and can respond with false or true)
src/mem/bridge.cc:
src/mem/bridge.hh:
    Change recvRetry() to not accept a packet. Sendtiming should be called again (and can respond with false or true)
    Removed Port Blocked/Unblocked and replaced with sendRetry().
    Remove posibility of packet mangling if packet is going to be refused anyway.
src/mem/bus.cc:
src/mem/bus.hh:
    Add a very poor implementation of dealing with retries on timing requests. It is especially slow with tracing on since
    it ends up being O(N^2). But it's probably going to have to change for the real bus anyway, so it should be rewritten then
src/mem/port.hh:
    Change recvRetry() to not accept a packet. Sendtiming should be called again (and can respond with false or true)
    Removed Blocked/Unblocked port status, their functionality is really duplicated in the recvRetry() method

--HG--
extra : convert_revision : fab613404be54bfa7a4c67572bae7b559169e573

5 files changed, 92 insertions, 60 deletions

diff --git a/src/mem/bridge.cc b/src/mem/bridge.cc
index 736e8dc81..5b8b9164b 100644
--- a/src/mem/bridge.cc
+++ b/src/mem/bridge.cc
@@ -90,7 +90,17 @@ Bridge::BridgePort::recvTiming(Packet *pkt)
     DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
             pkt->getSrc(), pkt->getDest(), pkt->getAddr());
 
-    if (pkt->isResponse()) {
+    return otherPort->queueForSendTiming(pkt);
+}
+
+
+bool
+Bridge::BridgePort::queueForSendTiming(Packet *pkt)
+{
+    if (queueFull())
+        return false;
+
+   if (pkt->isResponse()) {
         // This is a response for a request we forwarded earlier.  The
         // corresponding PacketBuffer should be stored in the packet's
         // senderState field.
@@ -99,22 +109,16 @@ Bridge::BridgePort::recvTiming(Packet *pkt)
         // set up new packet dest & senderState based on values saved
         // from original request
         buf->fixResponse(pkt);
+        DPRINTF(BusBridge, "restoring  sender state: %#X, from packet buffer: %#X\n",
+                        pkt->senderState, buf);
         DPRINTF(BusBridge, "  is response, new dest %d\n", pkt->getDest());
         delete buf;
     }
 
-    return otherPort->queueForSendTiming(pkt);
-}
-
-
-bool
-Bridge::BridgePort::queueForSendTiming(Packet *pkt)
-{
-    if (queueFull())
-        return false;
-
     Tick readyTime = curTick + delay;
     PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
+    DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n",
+            buf->origSenderState, buf);
 
     // 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
@@ -126,43 +130,16 @@ Bridge::BridgePort::queueForSendTiming(Packet *pkt)
 
     sendQueue.push_back(buf);
 
-    // Did we just become blocked?  If yes, let other side know.
-    if (queueFull())
-        otherPort->sendStatusChange(Port::Blocked);
-
     return true;
 }
 
-
-void
-Bridge::BridgePort::finishSend(PacketBuffer *buf)
-{
-    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;
-        DPRINTF(BusBridge, "  successful: awaiting response (%d)\n",
-                outstandingResponses);
-    } else {
-        // no response expected... deallocate packet buffer now.
-        DPRINTF(BusBridge, "  successful: no response expected\n");
-        delete buf;
-    }
-
-    // If there are more packets to send, schedule event to try again.
-    if (!sendQueue.empty()) {
-        buf = sendQueue.front();
-        sendEvent.schedule(std::max(buf->ready, curTick + 1));
-    }
-}
-
-
 void
 Bridge::BridgePort::trySend()
 {
     assert(!sendQueue.empty());
 
+    bool was_full = queueFull();
+
     PacketBuffer *buf = sendQueue.front();
 
     assert(buf->ready <= curTick);
@@ -176,20 +153,41 @@ Bridge::BridgePort::trySend()
         // send successful
         sendQueue.pop_front();
         buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it
-        finishSend(buf);
+
+        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;
+            DPRINTF(BusBridge, "  successful: awaiting response (%d)\n",
+                    outstandingResponses);
+        } else {
+            // no response expected... deallocate packet buffer now.
+            DPRINTF(BusBridge, "  successful: no response expected\n");
+            delete buf;
+        }
+
+        // If there are more packets to send, schedule event to try again.
+        if (!sendQueue.empty()) {
+            buf = sendQueue.front();
+            sendEvent.schedule(std::max(buf->ready, curTick + 1));
+        }
+        // Let things start sending again
+        if (was_full) {
+          DPRINTF(BusBridge, "Queue was full, sending retry\n");
+          otherPort->sendRetry();
+        }
+
     } else {
         DPRINTF(BusBridge, "  unsuccessful\n");
     }
 }
 
 
-Packet *
+void
 Bridge::BridgePort::recvRetry()
 {
-    PacketBuffer *buf = sendQueue.front();
-    Packet *pkt = buf->pkt;
-    finishSend(buf);
-    return pkt;
+    trySend();
 }
 
 /** Function called by the port when the bus is receiving a Atomic
@@ -223,9 +221,6 @@ Bridge::BridgePort::recvFunctional(Packet *pkt)
 void
 Bridge::BridgePort::recvStatusChange(Port::Status status)
 {
-    if (status == Port::Blocked || status == Port::Unblocked)
-        return;
-
     otherPort->sendStatusChange(status);
 }
 
diff --git a/src/mem/bridge.hh b/src/mem/bridge.hh
index 8a5cbf92a..8c7af562c 100644
--- a/src/mem/bridge.hh
+++ b/src/mem/bridge.hh
@@ -38,7 +38,6 @@
 #include <inttypes.h>
 #include <queue>
 
-
 #include "mem/mem_object.hh"
 #include "mem/packet.hh"
 #include "mem/port.hh"
@@ -77,7 +76,8 @@ class Bridge : public MemObject
                   origSenderState(_pkt->senderState), origSrc(_pkt->getSrc()),
                   expectResponse(_pkt->needsResponse())
             {
-                pkt->senderState = this;
+                if (!pkt->isResponse())
+                    pkt->senderState = this;
             }
 
             void fixResponse(Packet *pkt)
@@ -146,7 +146,7 @@ class Bridge : public MemObject
 
         /** When receiving a retry request from the peer port,
             pass it to the bridge. */
-        virtual Packet* recvRetry();
+        virtual void recvRetry();
 
         /** When receiving a Atomic requestfrom the peer port,
             pass it to the bridge. */
diff --git a/src/mem/bus.cc b/src/mem/bus.cc
index cfc99a64f..aec3ef2f6 100644
--- a/src/mem/bus.cc
+++ b/src/mem/bus.cc
@@ -72,9 +72,35 @@ Bus::recvTiming(Packet *pkt)
         assert(dest != pkt->getSrc()); // catch infinite loops
         port = interfaces[dest];
     }
-    return port->sendTiming(pkt);
+    if (port->sendTiming(pkt))  {
+        // packet was successfully sent, just return true.
+        return true;
+    }
+
+    // packet not successfully sent
+    retryList.push_back(interfaces[pkt->getSrc()]);
+    return false;
+}
+
+void
+Bus::recvRetry(int id)
+{
+    // Go through all the elements on the list calling sendRetry on each
+    // This is not very efficient at all but it works. Ultimately we should end
+    // up with something that is more intelligent.
+    int initialSize = retryList.size();
+    int i;
+    Port *p;
+
+    for (i = 0; i < initialSize; i++) {
+        assert(retryList.size() > 0);
+        p = retryList.front();
+        retryList.pop_front();
+        p->sendRetry();
+    }
 }
 
+
 Port *
 Bus::findPort(Addr addr, int id)
 {
diff --git a/src/mem/bus.hh b/src/mem/bus.hh
index 5eeb07904..774f9f3a4 100644
--- a/src/mem/bus.hh
+++ b/src/mem/bus.hh
@@ -67,6 +67,10 @@ class Bus : public MemObject
         transaction.*/
     void recvFunctional(Packet *pkt);
 
+    /** Timing function called by port when it is once again able to process
+     * requests. */
+    void recvRetry(int id);
+
     /** Function called by the port when the bus is recieving a status change.*/
     void recvStatusChange(Port::Status status, int id);
 
@@ -126,6 +130,11 @@ class Bus : public MemObject
         virtual void recvStatusChange(Status status)
         { bus->recvStatusChange(status, id); }
 
+        /** When reciving a retry from the peer port (at id),
+            pass it to the bus. */
+        virtual void recvRetry()
+        { bus->recvRetry(id); }
+
         // This should return all the 'owned' addresses that are
         // downstream from this bus, yes?  That is, the union of all
         // the 'owned' address ranges of all the other interfaces on
@@ -143,6 +152,10 @@ class Bus : public MemObject
         connected to this bus.*/
     std::vector<Port*> interfaces;
 
+    /** An array of pointers to ports that retry should be called on because the
+     * original send failed for whatever reason.*/
+    std::list<Port*> retryList;
+
   public:
 
     /** A function used to return the port associated with this bus object. */
diff --git a/src/mem/port.hh b/src/mem/port.hh
index f9103865e..79fbf1fdb 100644
--- a/src/mem/port.hh
+++ b/src/mem/port.hh
@@ -92,11 +92,9 @@ class Port
     virtual ~Port() {};
 
     // mey be better to use subclasses & RTTI?
-    /** Holds the ports status.  Keeps track if it is blocked, or has
-        calculated a range change. */
+    /** Holds the ports status.  Currently just that a range recomputation needs
+     * to be done. */
     enum Status {
-        Blocked,
-        Unblocked,
         RangeChange
     };
 
@@ -140,7 +138,7 @@ class Port
         wait.  This shouldn't be valid for response paths (IO Devices).
         so it is set to panic if it isn't already defined.
     */
-    virtual Packet *recvRetry() { panic("??"); }
+    virtual void recvRetry() { panic("??"); }
 
     /** Called by a peer port in order to determine the block size of the
         device connected to this port.  It sometimes doesn't make sense for
@@ -165,7 +163,7 @@ class Port
         port receive function.
         @return This function returns if the send was succesful in it's
         recieve. If it was a failure, then the port will wait for a recvRetry
-        at which point it can issue a successful sendTiming.  This is used in
+        at which point it can possibly issue a successful sendTiming.  This is used in
         case a cache has a higher priority request come in while waiting for
         the bus to arbitrate.
     */
@@ -194,7 +192,7 @@ class Port
     /** When a timing access doesn't return a success, some time later the
         Retry will be sent.
     */
-    Packet *sendRetry() { return peer->recvRetry(); }
+    void sendRetry() { return peer->recvRetry(); }
 
     /** Called by the associated device if it wishes to find out the blocksize
         of the device on attached to the peer port.