ruby: new atomics implementation

This patch changes the way that Ruby handles atomic RMW instructions. This implementation, unlike the prior one, is protocol independent. It works by locking an address from the sequencer immediately after the read portion of an RMW completes. When that address is locked, the coherence controller will only satisfy requests coming from one port (e.g., the mandatory queue) and will ignore all others. After the write portion completed, the line is unlocked. This should also work with multi-line atomics, as long as the blocks are always acquired in the same order.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/mem/ruby/buffers/MessageBuffer.hh b/src/mem/ruby/buffers/MessageBuffer.hh
index 8440c3335..950423ee5 100644
--- a/src/mem/ruby/buffers/MessageBuffer.hh
+++ b/src/mem/ruby/buffers/MessageBuffer.hh
@@ -64,6 +64,11 @@ public:
             (m_prio_heap.peekMin().m_time <= g_eventQueue_ptr->getTime()));
   }
 
+  void delayHead() {
+    MessageBufferNode node = m_prio_heap.extractMin();
+    enqueue(node.m_msgptr, 1);
+  }
+
   bool areNSlotsAvailable(int n);
   int getPriority() { return m_priority_rank; }
   void setPriority(int rank) { m_priority_rank = rank; }