trace: Add simple built-in tracing backend

This patch adds a simple tracer which produces binary trace files.  To
try out the simple backend:

$ ./configure --trace-backend=simple
$ make

After running QEMU you can pretty-print the trace:

$ ./simpletrace.py trace-events trace.log

The output of simpletrace.py looks like this:

  qemu_realloc 0.699 ptr=0x24363f0 size=0x3 newptr=0x24363f0
  qemu_free 0.768 ptr=0x24363f0
  ^           ^---- timestamp delta (us)
  |____ trace event name

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

trace: Make trace record fields 64-bit

Explicitly use 64-bit fields in trace records so that timestamps and
magic numbers work for 32-bit host builds.

Includes fixes from Prerna Saxena <prerna@linux.vnet.ibm.com>.

Signed-off-by: Prerna Saxena <prerna@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

1 files changed, 93 insertions, 0 deletions

diff --git a/simpletrace.py b/simpletrace.py
new file mode 100755
index 0000000000..c2cf1682d0
--- /dev/null
+++ b/simpletrace.py
@@ -0,0 +1,93 @@
+#!/usr/bin/env python
+#
+# Pretty-printer for simple trace backend binary trace files
+#
+# Copyright IBM, Corp. 2010
+#
+# This work is licensed under the terms of the GNU GPL, version 2.  See
+# the COPYING file in the top-level directory.
+#
+# For help see docs/tracing.txt
+
+import sys
+import struct
+import re
+
+header_event_id = 0xffffffffffffffff
+header_magic    = 0xf2b177cb0aa429b4
+header_version  = 0
+
+trace_fmt = '=QQQQQQQQ'
+trace_len = struct.calcsize(trace_fmt)
+event_re  = re.compile(r'(disable\s+)?([a-zA-Z0-9_]+)\(([^)]*)\)\s+"([^"]*)"')
+
+def err(msg):
+    sys.stderr.write(msg + '\n')
+    sys.exit(1)
+
+def parse_events(fobj):
+    """Parse a trace-events file."""
+
+    def get_argnames(args):
+        """Extract argument names from a parameter list."""
+        return tuple(arg.split()[-1].lstrip('*') for arg in args.split(','))
+
+    events = {}
+    event_num = 0
+    for line in fobj:
+        m = event_re.match(line.strip())
+        if m is None:
+            continue
+
+        disable, name, args, fmt = m.groups()
+        events[event_num] = (name,) + get_argnames(args)
+        event_num += 1
+    return events
+
+def read_record(fobj):
+    """Deserialize a trace record from a file."""
+    s = fobj.read(trace_len)
+    if len(s) != trace_len:
+        return None
+    return struct.unpack(trace_fmt, s)
+
+def read_trace_file(fobj):
+    """Deserialize trace records from a file."""
+    header = read_record(fobj)
+    if header is None or \
+       header[0] != header_event_id or \
+       header[1] != header_magic or \
+       header[2] != header_version:
+        err('not a trace file or incompatible version')
+
+    while True:
+        rec = read_record(fobj)
+        if rec is None:
+            break
+
+        yield rec
+
+class Formatter(object):
+    def __init__(self, events):
+        self.events = events
+        self.last_timestamp = None
+
+    def format_record(self, rec):
+        if self.last_timestamp is None:
+            self.last_timestamp = rec[1]
+        delta_ns = rec[1] - self.last_timestamp
+        self.last_timestamp = rec[1]
+
+        event = self.events[rec[0]]
+        fields = [event[0], '%0.3f' % (delta_ns / 1000.0)]
+        for i in xrange(1, len(event)):
+            fields.append('%s=0x%x' % (event[i], rec[i + 1]))
+        return ' '.join(fields)
+
+if len(sys.argv) != 3:
+    err('usage: %s <trace-events> <trace-file>' % sys.argv[0])
+
+events = parse_events(open(sys.argv[1], 'r'))
+formatter = Formatter(events)
+for rec in read_trace_file(open(sys.argv[2], 'rb')):
+    print formatter.format_record(rec)