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simpletrace: add simpletrace.py --no-header option

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It can be useful to read simpletrace files that have no header.  For
example, a ring buffer may not have a header record but can still be
processed if the user is sure the file format version is compatible.

  $ scripts/simpletrace.py --no-header trace-events trace-file

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2014-06-22 21:46:06 +08:00
parent 3f8b112d6b
commit 15327c3df0
1 changed files with 17 additions and 7 deletions
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24
scripts/simpletrace.py
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@ -58,8 +58,8 @@ def read_record(edict, fobj):
rechdr = read_header(fobj, rec_header_fmt) rechdr = read_header(fobj, rec_header_fmt)
return get_record(edict, rechdr, fobj) # return tuple of record elements return get_record(edict, rechdr, fobj) # return tuple of record elements
def read_trace_file(edict, fobj): def read_trace_header(fobj):
"""Deserialize trace records from a file, yielding record tuples (event_num, timestamp, pid, arg1, ..., arg6).""" """Read and verify trace file header"""
header = read_header(fobj, log_header_fmt) header = read_header(fobj, log_header_fmt)
if header is None or \ if header is None or \
header[0] != header_event_id or \ header[0] != header_event_id or \
@ -73,6 +73,8 @@ def read_trace_file(edict, fobj):
raise ValueError('Log format %d not supported with this QEMU release!' raise ValueError('Log format %d not supported with this QEMU release!'
% log_version) % log_version)
def read_trace_records(edict, fobj):
"""Deserialize trace records from a file, yielding record tuples (event_num, timestamp, pid, arg1, ..., arg6)."""
while True: while True:
rec = read_record(edict, fobj) rec = read_record(edict, fobj)
if rec is None: if rec is None:
@ -102,13 +104,16 @@ class Analyzer(object):
"""Called at the end of the trace.""" """Called at the end of the trace."""
pass pass
def process(events, log, analyzer): def process(events, log, analyzer, read_header=True):
"""Invoke an analyzer on each event in a log.""" """Invoke an analyzer on each event in a log."""
if isinstance(events, str): if isinstance(events, str):
events = _read_events(open(events, 'r')) events = _read_events(open(events, 'r'))
if isinstance(log, str): if isinstance(log, str):
log = open(log, 'rb') log = open(log, 'rb')
if read_header:
read_trace_header(log)
dropped_event = Event.build("Dropped_Event(uint64_t num_events_dropped)") dropped_event = Event.build("Dropped_Event(uint64_t num_events_dropped)")
edict = {dropped_event_id: dropped_event} edict = {dropped_event_id: dropped_event}
@ -137,7 +142,7 @@ def process(events, log, analyzer):
analyzer.begin() analyzer.begin()
fn_cache = {} fn_cache = {}
for rec in read_trace_file(edict, log): for rec in read_trace_records(edict, log):
event_num = rec[0] event_num = rec[0]
event = edict[event_num] event = edict[event_num]
if event_num not in fn_cache: if event_num not in fn_cache:
@ -152,12 +157,17 @@ def run(analyzer):
advanced scripts will want to call process() instead.""" advanced scripts will want to call process() instead."""
import sys import sys
if len(sys.argv) != 3: read_header = True
sys.stderr.write('usage: %s <trace-events> <trace-file>\n' % sys.argv[0]) if len(sys.argv) == 4 and sys.argv[1] == '--no-header':
read_header = False
del sys.argv[1]
elif len(sys.argv) != 3:
sys.stderr.write('usage: %s [--no-header] <trace-events> ' \
'<trace-file>\n' % sys.argv[0])
sys.exit(1) sys.exit(1)
events = _read_events(open(sys.argv[1], 'r')) events = _read_events(open(sys.argv[1], 'r'))
process(events, sys.argv[2], analyzer) process(events, sys.argv[2], analyzer, read_header=read_header)
if __name__ == '__main__': if __name__ == '__main__':
class Formatter(Analyzer): class Formatter(Analyzer):