mem: Add probe support to the CommMonitor

This changeset adds a standardized probe point type to monitor packets
in the memory system and adds two probe points to the CommMonitor
class. These probe points enable monitoring of successfully delivered
requests and successfully delivered responses.

Memory system probe listeners should use the BaseMemProbe base class
to provide a unified configuration interface and reuse listener
registration code. Unlike the ProbeListenerObject class, the
BaseMemProbe allows objects to be wired to multiple ProbeManager
instances as long as they use the same probe point name.

1 files changed, 38 insertions, 9 deletions

diff --git a/src/mem/comm_monitor.cc b/src/mem/comm_monitor.cc
index d95a2fd5a..bd9b26816 100644
--- a/src/mem/comm_monitor.cc
+++ b/src/mem/comm_monitor.cc
@@ -139,6 +139,13 @@ CommMonitor::init()
 
 }
 
+void
+CommMonitor::regProbePoints()
+{
+    ppPktReq.reset(new ProbePoints::Packet(getProbeManager(), "PktRequest"));
+    ppPktResp.reset(new ProbePoints::Packet(getProbeManager(), "PktResponse"));
+}
+
 BaseMasterPort&
 CommMonitor::getMasterPort(const std::string& if_name, PortID idx)
 {
@@ -174,6 +181,8 @@ CommMonitor::recvFunctionalSnoop(PacketPtr pkt)
 Tick
 CommMonitor::recvAtomic(PacketPtr pkt)
 {
+    ppPktReq->notify(pkt);
+
     // do stack distance calculations if enabled
     if (stackDistCalc)
         stackDistCalc->update(pkt->cmd, pkt->getAddr());
@@ -191,7 +200,10 @@ CommMonitor::recvAtomic(PacketPtr pkt)
         traceStream->write(pkt_msg);
     }
 
-    return masterPort.sendAtomic(pkt);
+    const Tick delay(masterPort.sendAtomic(pkt));
+    assert(pkt->isResponse());
+    ppPktResp->notify(pkt);
+    return delay;
 }
 
 Tick
@@ -208,14 +220,15 @@ CommMonitor::recvTimingReq(PacketPtr pkt)
 
     // Store relevant fields of packet, because packet may be modified
     // or even deleted when sendTiming() is called.
-    bool is_read = pkt->isRead();
-    bool is_write = pkt->isWrite();
-    MemCmd cmd = pkt->cmd;
-    int cmd_idx = pkt->cmdToIndex();
-    Request::FlagsType req_flags = pkt->req->getFlags();
-    unsigned size = pkt->getSize();
-    Addr addr = pkt->getAddr();
-    bool expects_response = pkt->needsResponse() && !pkt->memInhibitAsserted();
+    const bool is_read = pkt->isRead();
+    const bool is_write = pkt->isWrite();
+    const MemCmd cmd = pkt->cmd;
+    const int cmd_idx = pkt->cmdToIndex();
+    const Request::FlagsType req_flags = pkt->req->getFlags();
+    const unsigned size = pkt->getSize();
+    const Addr addr = pkt->getAddr();
+    const bool expects_response(
+        pkt->needsResponse() && !pkt->memInhibitAsserted());
 
     // If a cache miss is served by a cache, a monitor near the memory
     // would see a request which needs a response, but this response
@@ -234,6 +247,17 @@ CommMonitor::recvTimingReq(PacketPtr pkt)
         delete pkt->popSenderState();
     }
 
+    if (successful) {
+        // The receiver might already have modified the packet. We
+        // want to give the probe access to the original packet, which
+        // means we need to fake the original packet by temporarily
+        // restoring the command.
+        const MemCmd response_cmd(pkt->cmd);
+        pkt->cmd = cmd;
+        ppPktReq->notify(pkt);
+        pkt->cmd = response_cmd;
+    }
+
     // If successful and we are calculating stack distances, update
     // the calculator
     if (successful && stackDistCalc)
@@ -378,6 +402,11 @@ CommMonitor::recvTimingResp(PacketPtr pkt)
         }
     }
 
+    if (successful) {
+        assert(pkt->isResponse());
+        ppPktResp->notify(pkt);
+    }
+
     if (successful && is_read) {
         // Decrement number of outstanding read requests
         DPRINTF(CommMonitor, "Received read response\n");