mem: Add tracing support in the communication monitor

This patch adds packet tracing to the communication monitor using a
protobuf as the mechanism for creating the trace.

If no file is specified, then the tracing is disabled. If a file is
specified, then for every packet that is successfully sent, a protobuf
message is serialized to the file.

8 files changed, 137 insertions, 15 deletions

diff --git a/src/base/output.cc b/src/base/output.cc
index ee2e196ed..c0ddd0fae 100644
--- a/src/base/output.cc
+++ b/src/base/output.cc
@@ -145,7 +145,7 @@ OutputDirectory::directory() const
     return dir;
 }
 
-inline string
+string
 OutputDirectory::resolve(const string &name) const
 {
     return (name[0] != PATH_SEPARATOR) ? dir + name : name;
diff --git a/src/base/output.hh b/src/base/output.hh
index 68d9daf85..ef628882d 100644
--- a/src/base/output.hh
+++ b/src/base/output.hh
@@ -52,16 +52,6 @@ class OutputDirectory
     /** System-specific path separator character */
     static const char PATH_SEPARATOR = '/';
 
-    /**
-     * Returns relative file names prepended with name of this directory.
-     * Returns absolute file names unaltered.
-     *
-     * @param name file name to prepend with directory name
-     * @return file name prepended with base directory name or unaltered
-     *          absolute file name
-     */
-    std::string resolve(const std::string &name) const;
-
   protected:
     /**
      * Determines whether given file name corresponds to standard output
@@ -80,6 +70,16 @@ class OutputDirectory
     /** Destructor. */
     ~OutputDirectory();
 
+    /**
+     * Returns relative file names prepended with name of this directory.
+     * Returns absolute file names unaltered.
+     *
+     * @param name file name to prepend with directory name
+     * @return file name prepended with base directory name or unaltered
+     *          absolute file name
+     */
+    std::string resolve(const std::string &name) const;
+
     /** Opens a file (optionally compressed).
      *
      * Will open a file as a compressed stream if filename ends in .gz.
diff --git a/src/mem/CommMonitor.py b/src/mem/CommMonitor.py
index a34a57db4..3f9106cc4 100644
--- a/src/mem/CommMonitor.py
+++ b/src/mem/CommMonitor.py
@@ -49,6 +49,9 @@ class CommMonitor(MemObject):
     master = MasterPort("Master port")
     slave = SlavePort("Slave port")
 
+    # packet trace output file, disabled by default
+    trace_file = Param.String("", "Packet trace output file")
+
     # control the sample period window length of this monitor
     sample_period = Param.Clock("1ms", "Sample period for histograms")
 
diff --git a/src/mem/SConscript b/src/mem/SConscript
index 374f904a8..ca89418b5 100644
--- a/src/mem/SConscript
+++ b/src/mem/SConscript
@@ -30,17 +30,21 @@
 
 Import('*')
 
+# Only build the communication if we have support for protobuf as the
+# tracing relies on it
+if env['HAVE_PROTOBUF']:
+    SimObject('CommMonitor.py')
+    Source('comm_monitor.cc')
+
 SimObject('AddrMapper.py')
 SimObject('Bridge.py')
 SimObject('Bus.py')
-SimObject('CommMonitor.py')
 SimObject('MemObject.py')
 
 Source('addr_mapper.cc')
 Source('bridge.cc')
 Source('bus.cc')
 Source('coherent_bus.cc')
-Source('comm_monitor.cc')
 Source('mem_object.cc')
 Source('mport.cc')
 Source('noncoherent_bus.cc')
diff --git a/src/mem/comm_monitor.cc b/src/mem/comm_monitor.cc
index 7e98f64f6..88e549cbb 100644
--- a/src/mem/comm_monitor.cc
+++ b/src/mem/comm_monitor.cc
@@ -38,9 +38,12 @@
  *          Andreas Hansson
  */
 
+#include "base/callback.hh"
+#include "base/output.hh"
 #include "base/trace.hh"
 #include "debug/CommMonitor.hh"
 #include "mem/comm_monitor.hh"
+#include "proto/packet.pb.h"
 #include "sim/stats.hh"
 
 CommMonitor::CommMonitor(Params* params)
@@ -51,8 +54,31 @@ CommMonitor::CommMonitor(Params* params)
       samplePeriodTicks(params->sample_period),
       readAddrMask(params->read_addr_mask),
       writeAddrMask(params->write_addr_mask),
-      stats(params)
+      stats(params),
+      traceStream(NULL)
 {
+    // If we are using a trace file, then open the file,
+    if (params->trace_file != "") {
+        // If the trace file is not specified as an absolute path,
+        // append the current simulation output directory
+        std::string filename = simout.resolve(params->trace_file);
+        traceStream = new ProtoOutputStream(filename);
+
+        // Create a protobuf message for the header and write it to
+        // the stream
+        Message::PacketHeader header_msg;
+        header_msg.set_obj_id(name());
+        header_msg.set_tick_freq(SimClock::Frequency);
+        traceStream->write(header_msg);
+
+        // Register a callback to compensate for the destructor not
+        // being called. The callback forces the stream to flush and
+        // closes the output file.
+        Callback* cb = new MakeCallback<CommMonitor,
+            &CommMonitor::closeStreams>(this);
+        registerExitCallback(cb);
+    }
+
     // keep track of the sample period both in ticks and absolute time
     samplePeriod.setTick(params->sample_period);
 
@@ -61,6 +87,13 @@ CommMonitor::CommMonitor(Params* params)
             name(), samplePeriodTicks, samplePeriod);
 }
 
+void
+CommMonitor::closeStreams()
+{
+    if (traceStream != NULL)
+        delete traceStream;
+}
+
 CommMonitor*
 CommMonitorParams::create()
 {
@@ -154,6 +187,19 @@ CommMonitor::recvTimingReq(PacketPtr pkt)
         pkt->senderState = senderState;
     }
 
+    if (successful && traceStream != NULL) {
+        // Create a protobuf message representing the
+        // packet. Currently we do not preserve the flags in the
+        // trace.
+        Message::Packet pkt_msg;
+        pkt_msg.set_tick(curTick());
+        pkt_msg.set_cmd(pkt->cmdToIndex());
+        pkt_msg.set_addr(pkt->getAddr());
+        pkt_msg.set_size(pkt->getSize());
+
+        traceStream->write(pkt_msg);
+    }
+
     if (successful && isRead) {
         DPRINTF(CommMonitor, "Forwarded read request\n");
 
diff --git a/src/mem/comm_monitor.hh b/src/mem/comm_monitor.hh
index e59b8c467..271ae5fff 100644
--- a/src/mem/comm_monitor.hh
+++ b/src/mem/comm_monitor.hh
@@ -45,6 +45,7 @@
 #include "base/time.hh"
 #include "mem/mem_object.hh"
 #include "params/CommMonitor.hh"
+#include "proto/protoio.hh"
 
 /**
  * The communication monitor is a MemObject which can monitor statistics of
@@ -75,7 +76,13 @@ class CommMonitor : public MemObject
     CommMonitor(Params* params);
 
     /** Destructor */
-    ~CommMonitor() { }
+    ~CommMonitor() {}
+
+    /**
+     * Callback to flush and close all open output streams on exit. If
+     * we were calling the destructor it could be done there.
+     */
+    void closeStreams();
 
     virtual BaseMasterPort& getMasterPort(const std::string& if_name,
                                           PortID idx = InvalidPortID);
@@ -427,6 +434,9 @@ class CommMonitor : public MemObject
 
     /** Instantiate stats */
     MonitorStats stats;
+
+    /** Output stream for a potential trace. */
+    ProtoOutputStream* traceStream;
 };
 
 #endif //__MEM_COMM_MONITOR_HH__
diff --git a/src/proto/SConscript b/src/proto/SConscript
index ade891737..9bb6fd428 100644
--- a/src/proto/SConscript
+++ b/src/proto/SConscript
@@ -41,4 +41,5 @@ Import('*')
 
 # Only build if we have protobuf support
 if env['HAVE_PROTOBUF']:
+    ProtoBuf('packet.proto')
     Source('protoio.cc')
diff --git a/src/proto/packet.proto b/src/proto/packet.proto
new file mode 100644
index 000000000..bfeee6a44
--- /dev/null
+++ b/src/proto/packet.proto
@@ -0,0 +1,58 @@
+// Copyright (c) 2012 ARM Limited
+// All rights reserved
+//
+// The license below extends only to copyright in the software and shall
+// not be construed as granting a license to any other intellectual
+// property including but not limited to intellectual property relating
+// to a hardware implementation of the functionality of the software
+// licensed hereunder.  You may use the software subject to the license
+// terms below provided that you ensure that this notice is replicated
+// unmodified and in its entirety in all distributions of the software,
+// modified or unmodified, in source code or in binary form.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met: redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer;
+// redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution;
+// neither the name of the copyright holders nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Authors: Andreas Hansson
+
+// Put all the generated messages in a namespace
+package Message;
+
+// Packet header with the identifier describing what object captured
+// the trace, the version of this file format, and the tick frequency
+// for all the packet time stamps.
+message PacketHeader {
+  required string obj_id = 1;
+  optional uint32 ver = 2 [default = 0];
+  required uint64 tick_freq = 3;
+}
+
+// Each packet in the trace contains a tick (which can be translated
+// to absolute time using the frequency in the header), the command,
+// the address, and the size in bytes
+message Packet {
+  required uint64 tick = 1;
+  required uint32 cmd = 2;
+  required uint64 addr = 3;
+  required uint32 size = 4;
+}