mem: add boolean to disable PacketQueue's size sanity check

the sanity check, while generally useful for exposing memory system bugs,
may be spurious with respect to GPU workloads, which may generate many more
requests than typical CPU workloads. the large number of requests generated
by the GPU may cause the req/resp queues to back up, thus queueing more than
100 packets.

2 files changed, 24 insertions, 5 deletions

diff --git a/src/mem/packet_queue.cc b/src/mem/packet_queue.cc
index a9fe29e86..ca8422f52 100644
--- a/src/mem/packet_queue.cc
+++ b/src/mem/packet_queue.cc
@@ -48,9 +48,10 @@
 
 using namespace std;
 
-PacketQueue::PacketQueue(EventManager& _em, const std::string& _label)
-    : em(_em), sendEvent(this), label(_label),
-      waitingOnRetry(false)
+PacketQueue::PacketQueue(EventManager& _em, const std::string& _label,
+                         bool disable_sanity_check)
+    : em(_em), sendEvent(this), _disableSanityCheck(disable_sanity_check),
+      label(_label), waitingOnRetry(false)
 {
 }
 
@@ -114,7 +115,7 @@ PacketQueue::schedSendTiming(PacketPtr pkt, Tick when, bool force_order)
 
     // add a very basic sanity check on the port to ensure the
     // invisible buffer is not growing beyond reasonable limits
-    if (transmitList.size() > 100) {
+    if (!_disableSanityCheck && transmitList.size() > 100) {
         panic("Packet queue %s has grown beyond 100 packets\n",
               name());
     }
diff --git a/src/mem/packet_queue.hh b/src/mem/packet_queue.hh
index 866a4477a..b1001e75d 100644
--- a/src/mem/packet_queue.hh
+++ b/src/mem/packet_queue.hh
@@ -89,6 +89,13 @@ class PacketQueue : public Drainable
     /** Event used to call processSendEvent. */
     EventWrapper<PacketQueue, &PacketQueue::processSendEvent> sendEvent;
 
+     /*
+      * Optionally disable the sanity check
+      * on the size of the transmitList. The
+      * sanity check will be enabled by default.
+      */
+    bool _disableSanityCheck;
+
   protected:
 
     /** Label to use for print request packets label stack. */
@@ -123,8 +130,11 @@ class PacketQueue : public Drainable
      *
      * @param _em Event manager used for scheduling this queue
      * @param _label Label to push on the label stack for print request packets
+     * @param disable_sanity_check Flag used to disable the sanity check
+     *        on the size of the transmitList. The check is enabled by default.
      */
-    PacketQueue(EventManager& _em, const std::string& _label);
+    PacketQueue(EventManager& _em, const std::string& _label,
+                bool disable_sanity_check = false);
 
     /**
      * Virtual desctructor since the class may be used as a base class.
@@ -187,6 +197,14 @@ class PacketQueue : public Drainable
      */
     void retry();
 
+    /**
+      * This allows a user to explicitly disable the sanity check
+      * on the size of the transmitList, which is enabled by default.
+      * Users must use this function to explicitly disable the sanity
+      * check.
+      */
+    void disableSanityCheck() { _disableSanityCheck = true; }
+
     DrainState drain() override;
 };