Currently simpletrace assumes that events are given IDs starting from 0, based on the order in which they appear in the trace-events file, with no gaps. When the trace-events file is split up, this assumption becomes problematic. To deal with this, extend the simpletrace format so that it outputs a table of event name <-> ID mappings. That will allow QEMU to assign arbitrary IDs to events without breaking simpletrace parsing. The v3 simple trace format was FILE HEADER EVENT TRACE RECORD 0 EVENT TRACE RECORD 1 ... EVENT TRACE RECORD N The v4 simple trace format is now FILE HEADER EVENT MAPPING RECORD 0 EVENT MAPPING RECORD 1 ... EVENT MAPPING RECORD M EVENT TRACE RECORD RECORD 0 EVENT TRACE RECORD RECORD 1 ... EVENT TRACE RECORD N Although this shows all the mapping records being emitted upfront, this is not required by the format. While the main simpletrace backend will emit all mappings at startup, the systemtap simpletrace.stp script will emit the mappings at first use. eg FILE HEADER ... EVENT MAPPING RECORD 0 EVENT TRACE RECORD RECORD 0 EVENT TRACE RECORD RECORD 1 EVENT MAPPING RECORD 1 EVENT TRACE RECORD RECORD 2 ... EVENT TRACE RECORD N This is more space efficient given that most trace records only include a subset of events. In modifying the systemtap simpletrace code, a 'begin' probe was added to emit the trace event header, so you no longer need to add '--no-header' when running simpletrace.py for systemtap generated trace files. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 1475588159-30598-12-git-send-email-berrange@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
218 lines
6.8 KiB
Python
Executable file
218 lines
6.8 KiB
Python
Executable file
#!/usr/bin/env python
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#
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# Pretty-printer for simple trace backend binary trace files
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#
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# Copyright IBM, Corp. 2010
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#
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# This work is licensed under the terms of the GNU GPL, version 2. See
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# the COPYING file in the top-level directory.
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#
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# For help see docs/tracing.txt
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import struct
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import re
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import inspect
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from tracetool import _read_events, Event
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from tracetool.backend.simple import is_string
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header_event_id = 0xffffffffffffffff
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header_magic = 0xf2b177cb0aa429b4
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dropped_event_id = 0xfffffffffffffffe
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record_type_mapping = 0
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record_type_event = 1
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log_header_fmt = '=QQQ'
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rec_header_fmt = '=QQII'
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def read_header(fobj, hfmt):
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'''Read a trace record header'''
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hlen = struct.calcsize(hfmt)
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hdr = fobj.read(hlen)
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if len(hdr) != hlen:
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return None
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return struct.unpack(hfmt, hdr)
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def get_record(edict, idtoname, rechdr, fobj):
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"""Deserialize a trace record from a file into a tuple
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(name, timestamp, pid, arg1, ..., arg6)."""
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if rechdr is None:
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return None
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if rechdr[0] != dropped_event_id:
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event_id = rechdr[0]
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name = idtoname[event_id]
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rec = (name, rechdr[1], rechdr[3])
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event = edict[name]
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for type, name in event.args:
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if is_string(type):
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l = fobj.read(4)
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(len,) = struct.unpack('=L', l)
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s = fobj.read(len)
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rec = rec + (s,)
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else:
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(value,) = struct.unpack('=Q', fobj.read(8))
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rec = rec + (value,)
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else:
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rec = ("dropped", rechdr[1], rechdr[3])
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(value,) = struct.unpack('=Q', fobj.read(8))
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rec = rec + (value,)
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return rec
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def get_mapping(fobj):
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(event_id, ) = struct.unpack('=Q', fobj.read(8))
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(len, ) = struct.unpack('=L', fobj.read(4))
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name = fobj.read(len)
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return (event_id, name)
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def read_record(edict, idtoname, fobj):
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"""Deserialize a trace record from a file into a tuple (event_num, timestamp, pid, arg1, ..., arg6)."""
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rechdr = read_header(fobj, rec_header_fmt)
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return get_record(edict, idtoname, rechdr, fobj)
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def read_trace_header(fobj):
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"""Read and verify trace file header"""
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header = read_header(fobj, log_header_fmt)
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if header is None or \
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header[0] != header_event_id or \
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header[1] != header_magic:
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raise ValueError('Not a valid trace file!')
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log_version = header[2]
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if log_version not in [0, 2, 3, 4]:
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raise ValueError('Unknown version of tracelog format!')
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if log_version != 4:
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raise ValueError('Log format %d not supported with this QEMU release!'
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% log_version)
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def read_trace_records(edict, fobj):
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"""Deserialize trace records from a file, yielding record tuples (event_num, timestamp, pid, arg1, ..., arg6)."""
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idtoname = {
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dropped_event_id: "dropped"
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}
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while True:
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t = fobj.read(8)
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if len(t) == 0:
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break
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(rectype, ) = struct.unpack('=Q', t)
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if rectype == record_type_mapping:
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event_id, name = get_mapping(fobj)
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idtoname[event_id] = name
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else:
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rec = read_record(edict, idtoname, fobj)
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yield rec
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class Analyzer(object):
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"""A trace file analyzer which processes trace records.
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An analyzer can be passed to run() or process(). The begin() method is
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invoked, then each trace record is processed, and finally the end() method
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is invoked.
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If a method matching a trace event name exists, it is invoked to process
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that trace record. Otherwise the catchall() method is invoked."""
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def begin(self):
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"""Called at the start of the trace."""
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pass
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def catchall(self, event, rec):
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"""Called if no specific method for processing a trace event has been found."""
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pass
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def end(self):
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"""Called at the end of the trace."""
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pass
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def process(events, log, analyzer, read_header=True):
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"""Invoke an analyzer on each event in a log."""
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if isinstance(events, str):
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events = _read_events(open(events, 'r'))
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if isinstance(log, str):
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log = open(log, 'rb')
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if read_header:
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read_trace_header(log)
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dropped_event = Event.build("Dropped_Event(uint64_t num_events_dropped)")
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edict = {"dropped": dropped_event}
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for event in events:
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edict[event.name] = event
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def build_fn(analyzer, event):
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if isinstance(event, str):
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return analyzer.catchall
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fn = getattr(analyzer, event.name, None)
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if fn is None:
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return analyzer.catchall
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event_argcount = len(event.args)
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fn_argcount = len(inspect.getargspec(fn)[0]) - 1
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if fn_argcount == event_argcount + 1:
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# Include timestamp as first argument
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return lambda _, rec: fn(*((rec[1:2],) + rec[3:3 + event_argcount]))
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elif fn_argcount == event_argcount + 2:
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# Include timestamp and pid
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return lambda _, rec: fn(*rec[1:3 + event_argcount])
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else:
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# Just arguments, no timestamp or pid
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return lambda _, rec: fn(*rec[3:3 + event_argcount])
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analyzer.begin()
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fn_cache = {}
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for rec in read_trace_records(edict, log):
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event_num = rec[0]
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event = edict[event_num]
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if event_num not in fn_cache:
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fn_cache[event_num] = build_fn(analyzer, event)
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fn_cache[event_num](event, rec)
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analyzer.end()
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def run(analyzer):
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"""Execute an analyzer on a trace file given on the command-line.
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This function is useful as a driver for simple analysis scripts. More
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advanced scripts will want to call process() instead."""
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import sys
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read_header = True
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if len(sys.argv) == 4 and sys.argv[1] == '--no-header':
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read_header = False
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del sys.argv[1]
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elif len(sys.argv) != 3:
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sys.stderr.write('usage: %s [--no-header] <trace-events> ' \
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'<trace-file>\n' % sys.argv[0])
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sys.exit(1)
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events = _read_events(open(sys.argv[1], 'r'))
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process(events, sys.argv[2], analyzer, read_header=read_header)
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if __name__ == '__main__':
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class Formatter(Analyzer):
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def __init__(self):
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self.last_timestamp = None
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def catchall(self, event, rec):
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timestamp = rec[1]
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if self.last_timestamp is None:
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self.last_timestamp = timestamp
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delta_ns = timestamp - self.last_timestamp
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self.last_timestamp = timestamp
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fields = [event.name, '%0.3f' % (delta_ns / 1000.0),
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'pid=%d' % rec[2]]
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i = 3
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for type, name in event.args:
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if is_string(type):
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fields.append('%s=%s' % (name, rec[i]))
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else:
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fields.append('%s=0x%x' % (name, rec[i]))
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i += 1
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print ' '.join(fields)
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run(Formatter())
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