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authorDaniel P. Berrange <berrange@redhat.com>2016-10-04 14:35:50 +0100
committerStefan Hajnoczi <stefanha@redhat.com>2016-10-12 09:35:54 +0200
commit7f1b588f20d027730676e627713ae3bbf6baab04 (patch)
tree9b84c3d96793c3ea8ac31a3474dd3bc217621eb1 /scripts
parentef4c9fc8542e06b1d567172c04b0c0377c7ab0c5 (diff)
trace: emit name <-> ID mapping in simpletrace header
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>
Diffstat (limited to 'scripts')
-rwxr-xr-xscripts/simpletrace.py50
-rw-r--r--scripts/tracetool/format/simpletrace_stap.py24
2 files changed, 58 insertions, 16 deletions
diff --git a/scripts/simpletrace.py b/scripts/simpletrace.py
index 3916c6d14a..f40467a794 100755
--- a/scripts/simpletrace.py
+++ b/scripts/simpletrace.py
@@ -19,6 +19,9 @@ header_event_id = 0xffffffffffffffff
header_magic = 0xf2b177cb0aa429b4
dropped_event_id = 0xfffffffffffffffe
+record_type_mapping = 0
+record_type_event = 1
+
log_header_fmt = '=QQQ'
rec_header_fmt = '=QQII'
@@ -30,14 +33,16 @@ def read_header(fobj, hfmt):
return None
return struct.unpack(hfmt, hdr)
-def get_record(edict, rechdr, fobj):
- """Deserialize a trace record from a file into a tuple (event_num, timestamp, pid, arg1, ..., arg6)."""
+def get_record(edict, idtoname, rechdr, fobj):
+ """Deserialize a trace record from a file into a tuple
+ (name, timestamp, pid, arg1, ..., arg6)."""
if rechdr is None:
return None
- rec = (rechdr[0], rechdr[1], rechdr[3])
if rechdr[0] != dropped_event_id:
event_id = rechdr[0]
- event = edict[event_id]
+ name = idtoname[event_id]
+ rec = (name, rechdr[1], rechdr[3])
+ event = edict[name]
for type, name in event.args:
if is_string(type):
l = fobj.read(4)
@@ -48,15 +53,22 @@ def get_record(edict, rechdr, fobj):
(value,) = struct.unpack('=Q', fobj.read(8))
rec = rec + (value,)
else:
+ rec = ("dropped", rechdr[1], rechdr[3])
(value,) = struct.unpack('=Q', fobj.read(8))
rec = rec + (value,)
return rec
+def get_mapping(fobj):
+ (event_id, ) = struct.unpack('=Q', fobj.read(8))
+ (len, ) = struct.unpack('=L', fobj.read(4))
+ name = fobj.read(len)
+
+ return (event_id, name)
-def read_record(edict, fobj):
+def read_record(edict, idtoname, fobj):
"""Deserialize a trace record from a file into a tuple (event_num, timestamp, pid, arg1, ..., arg6)."""
rechdr = read_header(fobj, rec_header_fmt)
- return get_record(edict, rechdr, fobj) # return tuple of record elements
+ return get_record(edict, idtoname, rechdr, fobj)
def read_trace_header(fobj):
"""Read and verify trace file header"""
@@ -67,20 +79,30 @@ def read_trace_header(fobj):
raise ValueError('Not a valid trace file!')
log_version = header[2]
- if log_version not in [0, 2, 3]:
+ if log_version not in [0, 2, 3, 4]:
raise ValueError('Unknown version of tracelog format!')
- if log_version != 3:
+ if log_version != 4:
raise ValueError('Log format %d not supported with this QEMU release!'
% log_version)
def read_trace_records(edict, fobj):
"""Deserialize trace records from a file, yielding record tuples (event_num, timestamp, pid, arg1, ..., arg6)."""
+ idtoname = {
+ dropped_event_id: "dropped"
+ }
while True:
- rec = read_record(edict, fobj)
- if rec is None:
+ t = fobj.read(8)
+ if len(t) == 0:
break
- yield rec
+ (rectype, ) = struct.unpack('=Q', t)
+ if rectype == record_type_mapping:
+ event_id, name = get_mapping(fobj)
+ idtoname[event_id] = name
+ else:
+ rec = read_record(edict, idtoname, fobj)
+
+ yield rec
class Analyzer(object):
"""A trace file analyzer which processes trace records.
@@ -115,10 +137,10 @@ def process(events, log, analyzer, read_header=True):
read_trace_header(log)
dropped_event = Event.build("Dropped_Event(uint64_t num_events_dropped)")
- edict = {dropped_event_id: dropped_event}
+ edict = {"dropped": dropped_event}
- for num, event in enumerate(events):
- edict[num] = event
+ for event in events:
+ edict[event.name] = event
def build_fn(analyzer, event):
if isinstance(event, str):
diff --git a/scripts/tracetool/format/simpletrace_stap.py b/scripts/tracetool/format/simpletrace_stap.py
index 7e44bc1811..ac3580fbcc 100644
--- a/scripts/tracetool/format/simpletrace_stap.py
+++ b/scripts/tracetool/format/simpletrace_stap.py
@@ -21,6 +21,25 @@ from tracetool.format.stap import stap_escape
def generate(events, backend):
out('/* This file is autogenerated by tracetool, do not edit. */',
+ '',
+ 'global event_name_to_id_map',
+ 'global event_next_id',
+ 'function simple_trace_map_event(name)',
+ '',
+ '{',
+ ' if (!([name] in event_name_to_id_map)) {',
+ ' event_name_to_id_map[name] = event_next_id',
+ ' name_len = strlen(name)',
+ ' printf("%%8b%%8b%%4b%%.*s", 0, ',
+ ' event_next_id, name_len, name_len, name)',
+ ' event_next_id = event_next_id + 1',
+ ' }',
+ ' return event_name_to_id_map[name]',
+ '}',
+ 'probe begin',
+ '{',
+ ' printf("%%8b%%8b%%8b", 0xffffffffffffffff, 0xf2b177cb0aa429b4, 4)',
+ '}',
'')
for event_id, e in enumerate(events):
@@ -29,6 +48,7 @@ def generate(events, backend):
out('probe %(probeprefix)s.simpletrace.%(name)s = %(probeprefix)s.%(name)s ?',
'{',
+ ' id = simple_trace_map_event("%(name)s")',
probeprefix=probeprefix(),
name=e.name)
@@ -48,7 +68,7 @@ def generate(events, backend):
sizestr = ' + '.join(sizes)
# Generate format string and value pairs for record header and arguments
- fields = [('8b', str(event_id)),
+ fields = [('8b', 'id'),
('8b', 'gettimeofday_ns()'),
('4b', sizestr),
('4b', 'pid()')]
@@ -63,7 +83,7 @@ def generate(events, backend):
# Emit the entire record in a single SystemTap printf()
fmt_str = '%'.join(fmt for fmt, _ in fields)
arg_str = ', '.join(arg for _, arg in fields)
- out(' printf("%%%(fmt_str)s", %(arg_str)s)',
+ out(' printf("%%8b%%%(fmt_str)s", 1, %(arg_str)s)',
fmt_str=fmt_str, arg_str=arg_str)
out('}')