diff -r bd4fc2b06322 -r 212f4fdb3eaa src/mem/cache/cache_impl.hh
--- a/src/mem/cache/cache_impl.hh	Thu Feb 19 08:02:55 2015 +0000
+++ b/src/mem/cache/cache_impl.hh	Thu Feb 19 08:03:06 2015 +0000
@@ -1596,15 +1596,16 @@
         // invalidate it.
         pkt->cmd = MemCmd::ReadRespWithInvalidate;
     }
-    DPRINTF(Cache, "%s created response: %s address %x size %d\n",
-            __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize());
-    // Here we condiser forward_time, paying for just forward latency and
+    // Here we consider forward_time, paying for just forward latency and
     // also charging the delay provided by the xbar.
     // forward_time is used as send_time in next allocateWriteBuffer().
     Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
     // Here we reset the timing of the packet.
     pkt->headerDelay = pkt->payloadDelay = 0;
-    memSidePort->schedTimingSnoopResp(pkt, forward_time);
+    DPRINTF(Cache, "%s created response: %s address %x size %d tick: %lu\n",
+            __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize(),
+            forward_time);
+    memSidePort->schedTimingSnoopResp(pkt, forward_time, true);
 }
 
 template<class TagStore>
diff -r bd4fc2b06322 -r 212f4fdb3eaa src/mem/packet_queue.hh
--- a/src/mem/packet_queue.hh	Thu Feb 19 08:02:55 2015 +0000
+++ b/src/mem/packet_queue.hh	Thu Feb 19 08:03:06 2015 +0000
@@ -180,8 +180,10 @@
      *
      * @param pkt Packet to send
      * @param when Absolute time (in ticks) to send packet
+     * @param force_order Do not reorder packets despite timing, but keep them
+     *                    in insertion order.
      */
-    void schedSendTiming(PacketPtr pkt, Tick when);
+    void schedSendTiming(PacketPtr pkt, Tick when, bool force_order = false);
 
     /**
      * Retry sending a packet from the queue. Note that this is not
diff -r bd4fc2b06322 -r 212f4fdb3eaa src/mem/packet_queue.cc
--- a/src/mem/packet_queue.cc	Thu Feb 19 08:02:55 2015 +0000
+++ b/src/mem/packet_queue.cc	Thu Feb 19 08:03:06 2015 +0000
@@ -100,10 +100,11 @@
 }
 
 void
-PacketQueue::schedSendTiming(PacketPtr pkt, Tick when)
+PacketQueue::schedSendTiming(PacketPtr pkt, Tick when, bool force_order)
 {
-    DPRINTF(PacketQueue, "%s for %s address %x size %d\n", __func__,
-            pkt->cmdString(), pkt->getAddr(), pkt->getSize());
+    DPRINTF(PacketQueue, "%s for %s address %x size %d when %lu ord: %i\n",
+            __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize(), when,
+            force_order);
 
     // we can still send a packet before the end of this tick
     assert(when >= curTick());
@@ -118,9 +119,26 @@
               name());
     }
 
+    // if requested, force the timing to be in-order by changing the when
+    // parameter
+    if (force_order && !transmitList.empty()) {
+        Tick back = transmitList.back().tick;
+
+        // fudge timing if required; relies on the code below to do the right
+        // thing (push_back) with the updated time-stamp
+        if (when < back) {
+            DPRINTF(PacketQueue, "%s force_order shifted packet %s address "\
+                    "%x from %lu to %lu\n", __func__, pkt->cmdString(),
+                    pkt->getAddr(), when, back);
+            when = back;
+        }
+    }
+
     // nothing on the list, or earlier than current front element,
     // schedule an event
     if (transmitList.empty() || when < transmitList.front().tick) {
+        // force_order-ed in here only when list is empty
+        assert(!force_order || transmitList.empty());
         // note that currently we ignore a potentially outstanding retry
         // and could in theory put a new packet at the head of the
         // transmit list before retrying the existing packet
@@ -143,6 +161,9 @@
         return;
     }
 
+    // forced orders never need insertion in the middle
+    assert(!force_order);
+
     // this belongs in the middle somewhere, insertion sort
     auto i = transmitList.begin();
     ++i; // already checked for insertion at front
diff -r bd4fc2b06322 -r 212f4fdb3eaa src/mem/qport.hh
--- a/src/mem/qport.hh	Thu Feb 19 08:02:55 2015 +0000
+++ b/src/mem/qport.hh	Thu Feb 19 08:03:06 2015 +0000
@@ -155,8 +155,9 @@
      * @param pkt Packet to send
      * @param when Absolute time (in ticks) to send packet
      */
-    void schedTimingSnoopResp(PacketPtr pkt, Tick when)
-    { snoopRespQueue.schedSendTiming(pkt, when); }
+    void schedTimingSnoopResp(PacketPtr pkt, Tick when, bool force_order =
+                              false)
+    { snoopRespQueue.schedSendTiming(pkt, when, force_order); }
 
     /** Check the list of buffered packets against the supplied
      * functional request. */