ruby: Make MessageBuffers actually finite sized

When Ruby controllers stall messages in MessageBuffers, the buffer moves those
messages off the priority heap and into a per-address stall map. When buffers
are finite-sized, the test areNSlotsAvailable() only checks the size of the
priority heap, but ignores the stall map, so the map is allowed to grow
unbounded if the controller stalls numerous messages. This patch fixes the
problem by tracking the stall map size and testing the total number of messages
in the buffer appropriately.

1 files changed, 7 insertions, 2 deletions

diff --git a/src/mem/ruby/network/MessageBuffer.cc b/src/mem/ruby/network/MessageBuffer.cc
index 557e0e80e..b96b00504 100644
--- a/src/mem/ruby/network/MessageBuffer.cc
+++ b/src/mem/ruby/network/MessageBuffer.cc
@@ -40,7 +40,7 @@ using namespace std;
 using m5::stl_helpers::operator<<;
 
 MessageBuffer::MessageBuffer(const Params *p)
-    : SimObject(p),
+    : SimObject(p), m_stall_map_size(0),
     m_max_size(p->buffer_size), m_time_last_time_size_checked(0),
     m_time_last_time_enqueue(0), m_time_last_time_pop(0),
     m_last_arrival_time(0), m_strict_fifo(p->ordered),
@@ -99,7 +99,7 @@ MessageBuffer::areNSlotsAvailable(unsigned int n, Tick current_time)
     }
 
     // now compare the new size with our max size
-    if (current_size + n <= m_max_size) {
+    if (current_size + m_stall_map_size + n <= m_max_size) {
         return true;
     } else {
         DPRINTF(RubyQueue, "n: %d, current_size: %d, heap size: %d, "
@@ -289,6 +289,8 @@ MessageBuffer::reanalyzeMessages(Addr addr, Tick current_time)
     // scheduled for the current cycle so that the previously stalled messages
     // will be observed before any younger messages that may arrive this cycle
     //
+    m_stall_map_size -= m_stall_msg_map[addr].size();
+    assert(m_stall_map_size >= 0);
     reanalyzeList(m_stall_msg_map[addr], current_time);
     m_stall_msg_map.erase(addr);
 }
@@ -306,6 +308,8 @@ MessageBuffer::reanalyzeAllMessages(Tick current_time)
     //
     for (StallMsgMapType::iterator map_iter = m_stall_msg_map.begin();
          map_iter != m_stall_msg_map.end(); ++map_iter) {
+        m_stall_map_size -= map_iter->second.size();
+        assert(m_stall_map_size >= 0);
         reanalyzeList(map_iter->second, current_time);
     }
     m_stall_msg_map.clear();
@@ -327,6 +331,7 @@ MessageBuffer::stallMessage(Addr addr, Tick current_time)
     // these addresses change state.
     //
     (m_stall_msg_map[addr]).push_back(message);
+    m_stall_map_size++;
 }
 
 void