Merge zizzer.eecs.umich.edu:/bk/newmem

into  zeep.eecs.umich.edu:/home/gblack/m5/newmem_bus

--HG--
extra : convert_revision : 1749397443ccb320d32f8dd23c71ed0431d30cb7

3 files changed, 189 insertions, 48 deletions

diff --git a/src/mem/bus.cc b/src/mem/bus.cc
index 3c5283a77..2a38cb635 100644
--- a/src/mem/bus.cc
+++ b/src/mem/bus.cc
@@ -67,6 +67,44 @@ Bus::init()
         (*intIter)->sendStatusChange(Port::RangeChange);
 }
 
+Bus::BusFreeEvent::BusFreeEvent(Bus *_bus) : Event(&mainEventQueue), bus(_bus)
+{}
+
+void Bus::BusFreeEvent::process()
+{
+    bus->recvRetry(0);
+}
+
+const char * Bus::BusFreeEvent::description()
+{
+    return "bus became available";
+}
+
+void
+Bus::occupyBus(int numCycles)
+{
+    //Move up when the bus will next be free
+    //We avoid the use of divide by adding repeatedly
+    //This should be faster if the value is updated frequently, but should
+    //be may be slower otherwise.
+
+    //Bring tickNextIdle up to the present tick
+    //There is some potential ambiguity where a cycle starts, which might make
+    //a difference when devices are acting right around a cycle boundary. Using
+    //a < allows things which happen exactly on a cycle boundary to take up only
+    //the following cycle. Anthing that happens later will have to "wait" for the
+    //end of that cycle, and then start using the bus after that.
+    while (tickNextIdle < curTick)
+        tickNextIdle += clock;
+    //Advance it numCycles bus cycles.
+    //XXX Should this use the repeating add trick as well?
+    tickNextIdle += (numCycles * clock);
+    if (!busIdle.scheduled()) {
+        busIdle.schedule(tickNextIdle);
+    } else {
+        busIdle.reschedule(tickNextIdle);
+    }
+}
 
 /** Function called by the port when the bus is receiving a Timing
  * transaction.*/
@@ -77,52 +115,89 @@ Bus::recvTiming(Packet *pkt)
     DPRINTF(Bus, "recvTiming: packet src %d dest %d addr 0x%x cmd %s\n",
             pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
 
-    short dest = pkt->getDest();
-    if (dest == Packet::Broadcast) {
-        if ( timingSnoopPhase1(pkt) )
-        {
-            timingSnoopPhase2(pkt);
-            port = findPort(pkt->getAddr(), pkt->getSrc());
-        }
-        else
-        {
-            //Snoop didn't succeed
-            retryList.push_back(interfaces[pkt->getSrc()]);
-            return false;
+    Port *pktPort = interfaces[pkt->getSrc()];
+
+    // If the bus is busy, or other devices are in line ahead of the current one,
+    // put this device on the retry list.
+    if (tickNextIdle > curTick || (retryList.size() && pktPort != retryingPort)) {
+        addToRetryList(pktPort);
+        return false;
+    }
+
+    // If the bus is blocked, make the device wait.
+    if (!(port = findDestPort(pkt, pkt->getSrc()))) {
+        addToRetryList(pktPort);
+        return false;
+    }
+
+    // The packet will be sent. Figure out how long it occupies the bus.
+    int numCycles = 0;
+    // Requests need one cycle to send an address
+    if (pkt->isRequest())
+        numCycles++;
+    else if (pkt->isResponse() || pkt->hasData()) {
+        // If a packet has data, it needs ceil(size/width) cycles to send it
+        // We're using the "adding instead of dividing" trick again here
+        if (pkt->hasData()) {
+            int dataSize = pkt->getSize();
+            for (int transmitted = 0; transmitted < dataSize;
+                    transmitted += width) {
+                numCycles++;
+            }
+        } else {
+            // If the packet didn't have data, it must have been a response.
+            // Those use the bus for one cycle to send their data.
+            numCycles++;
         }
-    } else {
-        assert(dest >= 0 && dest < interfaces.size());
-        assert(dest != pkt->getSrc()); // catch infinite loops
-        port = interfaces[dest];
     }
+
+    occupyBus(numCycles);
+
     if (port->sendTiming(pkt))  {
-        // packet was successfully sent, just return true.
+        // Packet was successfully sent. Return true.
         return true;
     }
 
-    // packet not successfully sent
-    retryList.push_back(interfaces[pkt->getSrc()]);
+    // Packet not successfully sent. Leave or put it on the retry list.
+    addToRetryList(pktPort);
     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();
+    //If there's anything waiting...
+    if (retryList.size()) {
+        retryingPort = retryList.front();
+        retryingPort->sendRetry();
+        //If the retryingPort pointer isn't null, either sendTiming wasn't
+        //called, or it was and the packet was successfully sent.
+        if (retryingPort) {
+            retryList.pop_front();
+            retryingPort = 0;
+        }
     }
 }
 
+Port *
+Bus::findDestPort(PacketPtr pkt, int id)
+{
+    Port * port = NULL;
+    short dest = pkt->getDest();
+
+    if (dest == Packet::Broadcast) {
+        if (timingSnoopPhase1(pkt)) {
+            timingSnoopPhase2(pkt);
+            port = findPort(pkt->getAddr(), pkt->getSrc());
+        }
+        //else, port stays NULL
+    } else {
+        assert(dest >= 0 && dest < interfaces.size());
+        assert(dest != pkt->getSrc()); // catch infinite loops
+        port = interfaces[dest];
+    }
+    return port;
+}
 
 Port *
 Bus::findPort(Addr addr, int id)
@@ -381,16 +456,20 @@ Bus::addressRanges(AddrRangeList &resp, AddrRangeList &snoop, int id)
 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bus)
 
     Param<int> bus_id;
+    Param<int> clock;
+    Param<int> width;
 
 END_DECLARE_SIM_OBJECT_PARAMS(Bus)
 
 BEGIN_INIT_SIM_OBJECT_PARAMS(Bus)
-    INIT_PARAM(bus_id, "a globally unique bus id")
+    INIT_PARAM(bus_id, "a globally unique bus id"),
+    INIT_PARAM(clock, "bus clock speed"),
+    INIT_PARAM(width, "width of the bus (bits)")
 END_INIT_SIM_OBJECT_PARAMS(Bus)
 
 CREATE_SIM_OBJECT(Bus)
 {
-    return new Bus(getInstanceName(), bus_id);
+    return new Bus(getInstanceName(), bus_id, clock, width);
 }
 
 REGISTER_SIM_OBJECT("Bus", Bus)
diff --git a/src/mem/bus.hh b/src/mem/bus.hh
index 941389296..96f1152a6 100644
--- a/src/mem/bus.hh
+++ b/src/mem/bus.hh
@@ -46,11 +46,18 @@
 #include "mem/packet.hh"
 #include "mem/port.hh"
 #include "mem/request.hh"
+#include "sim/eventq.hh"
 
 class Bus : public MemObject
 {
     /** a globally unique id for this bus. */
     int busId;
+    /** the clock speed for the bus */
+    int clock;
+    /** the width of the bus in bits */
+    int width;
+    /** the next tick at which the bus will be idle */
+    Tick tickNextIdle;
 
     static const int defaultId = -1;
 
@@ -93,6 +100,15 @@ class Bus : public MemObject
      */
     Port *findPort(Addr addr, int id);
 
+    /** Finds the port a packet should be sent to. If the bus is blocked, no port
+     * is returned.
+     * @param pkt Packet to find a destination port for.
+     * @param id Id of the port this packet was received from
+     *           (to prevent loops)
+     */
+
+    Port *findDestPort(PacketPtr pkt, int id);
+
     /** Find all ports with a matching snoop range, except src port.  Keep in mind
      * that the ranges shouldn't overlap or you will get a double snoop to the same
      * interface.and the cache will assert out.
@@ -181,6 +197,22 @@ class Bus : public MemObject
 
     };
 
+    class BusFreeEvent : public Event
+    {
+        Bus * bus;
+
+      public:
+        BusFreeEvent(Bus * _bus);
+        void process();
+        const char *description();
+    };
+
+    BusFreeEvent busIdle;
+
+    void occupyBus(int numCycles);
+
+    Port * retryingPort;
+
     /** An array of pointers to the peer port interfaces
         connected to this bus.*/
     std::vector<Port*> interfaces;
@@ -189,6 +221,23 @@ class Bus : public MemObject
      * original send failed for whatever reason.*/
     std::list<Port*> retryList;
 
+    void addToRetryList(Port * port)
+    {
+        if (!retryingPort) {
+            // The device wasn't retrying a packet, or wasn't at an appropriate
+            // time.
+            retryList.push_back(port);
+        } else {
+            // The device was retrying a packet. It didn't work, so we'll leave
+            // it at the head of the retry list.
+            retryingPort = 0;
+
+            // We shouldn't be receiving a packet from one port when a different
+            // one is retrying.
+            assert(port == retryingPort);
+        }
+    }
+
     /** Port that handles requests that don't match any of the interfaces.*/
     Port *defaultPort;
 
@@ -199,8 +248,14 @@ class Bus : public MemObject
 
     virtual void init();
 
-    Bus(const std::string &n, int bus_id)
-        : MemObject(n), busId(bus_id), defaultPort(NULL)  {}
+    Bus(const std::string &n, int bus_id, int _clock, int _width)
+        : MemObject(n), busId(bus_id), clock(_clock), width(_width),
+        tickNextIdle(0), busIdle(this), retryingPort(0), defaultPort(NULL)
+    {
+        //Both the width and clock period must be positive
+        assert(width);
+        assert(clock);
+    }
 
 };
 
diff --git a/src/mem/packet.hh b/src/mem/packet.hh
index be9bf5f57..5c513ae7a 100644
--- a/src/mem/packet.hh
+++ b/src/mem/packet.hh
@@ -58,10 +58,6 @@ typedef std::list<PacketPtr> PacketList;
 #define NO_ALLOCATE 1 << 5
 #define SNOOP_COMMIT 1 << 6
 
-//For statistics we need max number of commands, hard code it at
-//20 for now.  @todo fix later
-#define NUM_MEM_CMDS 1 << 9
-
 /**
  * A Packet is used to encapsulate a transfer between two objects in
  * the memory system (e.g., the L1 and L2 cache).  (In contrast, a
@@ -164,6 +160,8 @@ class Packet
 
   private:
     /** List of command attributes. */
+    // If you add a new CommandAttribute, make sure to increase NUM_MEM_CMDS
+    // as well.
     enum CommandAttribute
     {
         IsRead		= 1 << 0,
@@ -174,30 +172,38 @@ class Packet
         IsResponse 	= 1 << 5,
         NeedsResponse	= 1 << 6,
         IsSWPrefetch    = 1 << 7,
-        IsHWPrefetch    = 1 << 8
+        IsHWPrefetch    = 1 << 8,
+        HasData		= 1 << 9
     };
 
+//For statistics we need max number of commands, hard code it at
+//20 for now.  @todo fix later
+#define NUM_MEM_CMDS 1 << 10
+
   public:
     /** List of all commands associated with a packet. */
     enum Command
     {
         InvalidCmd      = 0,
         ReadReq		= IsRead  | IsRequest | NeedsResponse,
-        WriteReq	= IsWrite | IsRequest | NeedsResponse,
-        WriteReqNoAck	= IsWrite | IsRequest,
-        ReadResp	= IsRead  | IsResponse | NeedsResponse,
+        WriteReq	= IsWrite | IsRequest | NeedsResponse | HasData,
+        WriteReqNoAck	= IsWrite | IsRequest | HasData,
+        ReadResp	= IsRead  | IsResponse | NeedsResponse | HasData,
         WriteResp	= IsWrite | IsResponse | NeedsResponse,
-        Writeback       = IsWrite | IsRequest,
+        Writeback       = IsWrite | IsRequest | HasData,
         SoftPFReq       = IsRead  | IsRequest | IsSWPrefetch | NeedsResponse,
         HardPFReq       = IsRead  | IsRequest | IsHWPrefetch | NeedsResponse,
-        SoftPFResp      = IsRead  | IsResponse | IsSWPrefetch | NeedsResponse,
-        HardPFResp      = IsRead  | IsResponse | IsHWPrefetch | NeedsResponse,
+        SoftPFResp      = IsRead  | IsResponse | IsSWPrefetch
+                                | NeedsResponse | HasData,
+        HardPFResp      = IsRead  | IsResponse | IsHWPrefetch
+                                | NeedsResponse | HasData,
         InvalidateReq   = IsInvalidate | IsRequest,
-        WriteInvalidateReq = IsWrite | IsInvalidate | IsRequest,
+        WriteInvalidateReq = IsWrite | IsInvalidate | IsRequest | HasData,
         UpgradeReq      = IsInvalidate | IsRequest | NeedsResponse,
         UpgradeResp     = IsInvalidate | IsResponse | NeedsResponse,
         ReadExReq       = IsRead | IsInvalidate | IsRequest | NeedsResponse,
-        ReadExResp      = IsRead | IsInvalidate | IsResponse | NeedsResponse
+        ReadExResp      = IsRead | IsInvalidate | IsResponse
+                                | NeedsResponse | HasData
     };
 
     /** Return the string name of the cmd field (for debugging and
@@ -219,6 +225,7 @@ class Packet
     bool isResponse()	 { return (cmd & IsResponse) != 0; }
     bool needsResponse() { return (cmd & NeedsResponse) != 0; }
     bool isInvalidate()  { return (cmd & IsInvalidate) != 0; }
+    bool hasData()	 { return (cmd & HasData) != 0; }
 
     bool isCacheFill() { return (flags & CACHE_LINE_FILL) != 0; }
     bool isNoAllocate() { return (flags & NO_ALLOCATE) != 0; }