1 files changed, 28 insertions, 0 deletions
diff --git a/src/mem/ruby/network/MessageBuffer.hh b/src/mem/ruby/network/MessageBuffer.hh
index 2a82887cd..b1d04ab9a 100644
--- a/src/mem/ruby/network/MessageBuffer.hh
+++ b/src/mem/ruby/network/MessageBuffer.hh
@@ -137,9 +137,37 @@ class MessageBuffer : public SimObject
     // sorted and ensures a well-defined iteration order
     typedef std::map<Addr, std::list<MsgPtr> > StallMsgMapType;
 
+    /**
+     * A map from line addresses to lists of stalled messages for that line.
+     * If this buffer allows the receiver to stall messages, on a stall
+     * request, the stalled message is removed from the m_prio_heap and placed
+     * in the m_stall_msg_map. Messages are held there until the receiver
+     * requests they be reanalyzed, at which point they are moved back to
+     * m_prio_heap.
+     *
+     * NOTE: The stall map holds messages in the order in which they were
+     * initially received, and when a line is unblocked, the messages are
+     * moved back to the m_prio_heap in the same order. This prevents starving
+     * older requests with younger ones.
+     */
     StallMsgMapType m_stall_msg_map;
 
+    /**
+     * Current size of the stall map.
+     * Track the number of messages held in stall map lists. This is used to
+     * ensure that if the buffer is finite-sized, it blocks further requests
+     * when the m_prio_heap and m_stall_msg_map contain m_max_size messages.
+     */
+    int m_stall_map_size;
+
+    /**
+     * The maximum capacity. For finite-sized buffers, m_max_size stores a
+     * number greater than 0 to indicate the maximum allowed number of messages
+     * in the buffer at any time. To get infinitely-sized buffers, set buffer
+     * size: m_max_size = 0
+     */
     const unsigned int m_max_size;
+
     Tick m_time_last_time_size_checked;
     unsigned int m_size_last_time_size_checked;