util: Add a utility script for decoding packet traces

This patch adds a simple Python script that reads the protobuf-encoded
packet traces (not gzipped), and prints them to an ASCII trace file.

The script can also be used as a template for other packet output
formats.

1 files changed, 189 insertions, 0 deletions

diff --git a/util/decode_packet_trace.py b/util/decode_packet_trace.py
new file mode 100755
index 000000000..9ee877e39
--- /dev/null
+++ b/util/decode_packet_trace.py
@@ -0,0 +1,189 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2013 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.
+#
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# 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 Google Inc. 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
+#
+
+# This script is used to dump protobuf packet traces to ASCII
+# format. It assumes that protoc has been executed and already
+# generated the Python package for the packet messages. This can
+# be done manually using:
+# protoc --python_out=. --proto_path=src/proto src/proto/packet.proto
+#
+# The ASCII trace format uses one line per request on the format cmd,
+# addr, size, tick,flags. For example:
+# r,128,64,4000,0
+# w,232123,64,500000,0
+
+import struct
+import sys
+import packet_pb2
+
+def DecodeVarint(in_file):
+    """
+    The decoding of the Varint32 is copied from
+    google.protobuf.internal.decoder and is only repeated here to
+    avoid depending on the internal functions in the library. If the
+    end of file is reached, return (0, 0).
+    """
+    result = 0
+    shift = 0
+    pos = 0
+    # Use a 32-bit mask
+    mask = 0xffffffff
+    while 1:
+        c = in_file.read(1)
+        if len(c) == 0:
+            return (0, 0)
+        b = struct.unpack('<B', c)[0]
+        result |= ((b & 0x7f) << shift)
+        pos += 1
+        if not (b & 0x80):
+            if result > 0x7fffffffffffffff:
+                result -= (1 << 64)
+                result |= ~mask
+            else:
+                result &= mask
+                return (result, pos)
+            shift += 7
+            if shift >= 64:
+                raise IOError('Too many bytes when decoding varint.')
+
+def decodeMessage(in_file, message):
+    """
+    Attempt to read a message from the file and decode it. Return
+    False if no message could be read.
+    """
+    try:
+        size, pos = DecodeVarint(in_file)
+        if size == 0:
+            return False
+        buf = in_file.read(size)
+        message.ParseFromString(buf)
+        return True
+    except IOError:
+        return False
+
+def main():
+    if len(sys.argv) != 3:
+        print "Usage: ", sys.argv[0], " <protobuf input> <ASCII output>"
+        exit(-1)
+
+    try:
+       proto_in = open(sys.argv[1], 'rb')
+    except IOError:
+        print "Failed to open ", sys.argv[1], " for reading"
+        exit(-1)
+
+    try:
+        ascii_out = open(sys.argv[2], 'w')
+    except IOError:
+        print "Failed to open ", sys.argv[2], " for writing"
+        exit(-1)
+
+    # Read the magic number in 4-byte Little Endian
+    magic_number = proto_in.read(4)
+
+    if magic_number != "gem5":
+        print "Unrecognized file"
+        exit(-1)
+
+    print "Parsing packet header"
+
+    # Add the packet header
+    header = packet_pb2.PacketHeader()
+    decodeMessage(proto_in, header)
+
+    print "Object id:", header.obj_id
+    print "Tick frequency:", header.tick_freq
+
+    print "Parsing packets"
+
+    num_packets = 0
+    ignored_flags = False
+    packet = packet_pb2.Packet()
+
+    # Decode the packet messages until we hit the end of the file
+    while decodeMessage(proto_in, packet):
+        num_packets += 1
+        # ReadReq is 1 and WriteReq is 4 in src/mem/packet.hh Command enum
+        cmd = 'r' if packet.cmd == 1 else ('w' if packet.cmd == 4 else 'u')
+        if packet.HasField('flags'):
+            # Currently not printing flags
+            ignored_flags = True
+        ascii_out.write('%s,%s,%s,%s\n' % (cmd, packet.addr, packet.size,
+                                           packet.tick))
+
+    print "Parsed packets:", num_packets
+    if ignored_flags:
+        print "Encountered packet flags that were ignored"
+
+    # We're done
+    ascii_out.close()
+    proto_in.close()
+
+if __name__ == "__main__":
+    main()