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ftrace: disable trace events not available in the target kernel

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In general we could be interested to define a common configuration to use
across different kernels. Thus, for a given set of experiments, some
trace events can be present only on some kernels and not others.

This patch introduces a check for the availability of trace events by
ensuring that we consider only those available in the kernel in use
in the target. In case of a trace event is not supported in the target
kernel we still log a warning.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
This commit is contained in:
Patrick Bellasi 2016-02-25 18:46:04 +00:00
parent d7bbad3aac
commit 78aa774e25
1 changed files with 28 additions and 1 deletions
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29
devlib/trace/ftrace.py
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@ -75,11 +75,12 @@ class FtraceCollector(TraceCollector):
self.host_binary = None
self.start_time = None
self.stop_time = None
self.event_string = _build_trace_events(self.events)
self.event_string = None
self.function_string = None
self._reset_needed = True
# Setup tracing paths
self.available_events_file = self.target.path.join(self.tracing_path, 'available_events')
self.available_functions_file = self.target.path.join(self.tracing_path, 'available_filter_functions')
self.buffer_size_file = self.target.path.join(self.tracing_path, 'buffer_size_kb')
self.current_tracer_file = self.target.path.join(self.tracing_path, 'current_tracer')
@ -104,6 +105,32 @@ class FtraceCollector(TraceCollector):
raise TargetError('No trace-cmd found on device and no_install=True is specified.')
self.target_binary = 'trace-cmd'
# Validate required events to be traced
available_events = self.target.execute(
'cat {}'.format(self.available_events_file)).splitlines()
selected_events = []
for event in self.events:
# Convert globs supported by FTrace into valid regexp globs
_event = event
if event[0] != '*':
_event = '*' + event
event_re = re.compile(_event.replace('*', '.*'))
# Select events matching the required ones
if len(filter(event_re.match, available_events)) == 0:
message = 'Event [{}] not available for tracing'.format(event)
if strict:
raise TargetError(message)
self.target.logger.warning(message)
else:
selected_events.append(event)
# If function profiling is enabled we always need at least one event.
# Thus, if not other events have been specified, try to add at least
# a tracepoint which is always available and possibly triggered few
# times.
if self.functions and len(selected_events) == 0:
selected_events = ['sched_wakeup_new']
self.event_string = _build_trace_events(selected_events)
# Check for function tracing support
if self.functions:
if not self.target.file_exists(self.function_profile_file):