mem: Separate waiting for the bus and waiting for a peer

This patch splits the retryList into a list of ports that are waiting
for the bus itself to become available, and a map that tracks the
ports where forwarding failed due to a peer not accepting the
packet. Thus, when a retry reaches the bus, it can be sent to the
appropriate port that initiated that transaction.

As a consequence of this patch, only ports that are really ready to go
will get a retry, thus reducing the amount of redundant failed
attempts. This patch also makes it easier to reason about the order of
servicing requests as the ports waiting for the bus are now clearly
FIFO and much easier to change if desired.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/mem/coherent_bus.hh b/src/mem/coherent_bus.hh
index 865bfe857..203d7f6b3 100644
--- a/src/mem/coherent_bus.hh
+++ b/src/mem/coherent_bus.hh
@@ -205,7 +205,7 @@ class CoherentBus : public BaseBus
         /** When reciving a retry from the peer port (at id),
             pass it to the bus. */
         virtual void recvRetry()
-        { bus.recvRetry(); }
+        { bus.recvRetry(id); }
 
         // Ask the bus to ask everyone on the bus what their block size is and
         // take the max of it. This might need to be changed a bit if we ever
@@ -248,7 +248,7 @@ class CoherentBus : public BaseBus
 
     /** Timing function called by port when it is once again able to process
      * requests. */
-    void recvRetry();
+    void recvRetry(PortID master_port_id);
 
     /**
      * Forward a timing packet to our snoopers, potentially excluding