mem: Make the buses multi layered

This patch makes the buses multi layered, and effectively creates a
crossbar structure with distributed contention ports at the
destination ports. Before this patch, a bus could have a single
request, response and snoop response in flight at any time, and with
these changes there can be as many requests as connected slaves (bus
master ports), and as many responses as connected masters (bus slave
ports).

Together with address interleaving, this patch enables us to create
high-throughput memory interconnects, e.g. 50+ GByte/s.

1 files changed, 9 insertions, 4 deletions

diff --git a/src/mem/coherent_bus.hh b/src/mem/coherent_bus.hh
index eb8b41e6a..d8ddd507c 100644
--- a/src/mem/coherent_bus.hh
+++ b/src/mem/coherent_bus.hh
@@ -72,12 +72,15 @@ class CoherentBus : public BaseBus
   protected:
 
     /**
-     * Declare the three layers of this bus, one for requests, one
+     * Declare the layers of this bus, one vector for requests, one
      * for responses, and one for snoop responses
      */
-    Layer<SlavePort> reqLayer;
-    Layer<MasterPort> respLayer;
-    Layer<SlavePort> snoopRespLayer;
+    typedef Layer<SlavePort,MasterPort> ReqLayer;
+    typedef Layer<MasterPort,SlavePort> RespLayer;
+    typedef Layer<SlavePort,MasterPort> SnoopLayer;
+    std::vector<ReqLayer*> reqLayers;
+    std::vector<RespLayer*> respLayers;
+    std::vector<SnoopLayer*> snoopLayers;
 
     /**
      * Declaration of the coherent bus slave port type, one will be
@@ -309,6 +312,8 @@ class CoherentBus : public BaseBus
 
     CoherentBus(const CoherentBusParams *p);
 
+    virtual ~CoherentBus();
+
     unsigned int drain(DrainManager *dm);
 
     virtual void regStats();