ruby: Check MessageBuffer space in garnet NetworkInterface

Garnet's NetworkInterface does not consider the size of MessageBuffers when
ejecting a Message from the network. Add a size check for the MessageBuffer
and only enqueue if space is available. If space is not available, the
message if placed in a queue and the credit is held. A callback from the
MessageBuffer is implemented to wake the NetworkInterface. If there are
messages in the stalled queue, they are processed first, in a FIFO manner
and if succesfully ejected, the credit is finally sent back upstream. The
maximum size of the stall queue is equal to the number of valid VNETs
with MessageBuffers attached.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/mem/ruby/network/MessageBuffer.hh b/src/mem/ruby/network/MessageBuffer.hh
index fc8feb03e..e6ec5ac4b 100644
--- a/src/mem/ruby/network/MessageBuffer.hh
+++ b/src/mem/ruby/network/MessageBuffer.hh
@@ -102,6 +102,9 @@ class MessageBuffer : public SimObject
     //! removes it from the queue and returns its total delay.
     Tick dequeue(Tick current_time, bool decrement_messages = true);
 
+    void registerDequeueCallback(std::function<void()> callback);
+    void unregisterDequeueCallback();
+
     void recycle(Tick current_time, Tick recycle_latency);
     bool isEmpty() const { return m_prio_heap.size() == 0; }
     bool isStallMapEmpty() { return m_stall_msg_map.size() == 0; }
@@ -133,6 +136,8 @@ class MessageBuffer : public SimObject
     Consumer* m_consumer;
     std::vector<MsgPtr> m_prio_heap;
 
+    std::function<void()> m_dequeue_callback;
+
     // use a std::map for the stalled messages as this container is
     // sorted and ensures a well-defined iteration order
     typedef std::map<Addr, std::list<MsgPtr> > StallMsgMapType;