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ftrace: add initial support for function profiling

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FTrace allows to collect profiling stats for kernel functions.
This patch adds the initial support which allows to specify a list of
kernel function we would like to profile.

If a list of functions to profile is specified, for each specified function
we check for that function to be actually one of the available instrumented
functions which can be monitored by FTrace.
If a function is not supported, we throw an expection so that the user
is aware about the analysis which is going to do.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
This commit is contained in:
Patrick Bellasi 2016-01-26 15:05:58 +00:00
parent bda7a16656
commit c5bc987226
1 changed files with 20 additions and 0 deletions
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20
devlib/trace/ftrace.py
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@ -45,6 +45,7 @@ class FtraceCollector(TraceCollector):
def __init__(self, target,
events=None,
functions=None,
buffer_size=None,
buffer_size_step=1000,
tracing_path='/sys/kernel/debug/tracing',
@ -55,6 +56,7 @@ class FtraceCollector(TraceCollector):
):
super(FtraceCollector, self).__init__(target)
self.events = events if events is not None else DEFAULT_EVENTS
self.functions = functions
self.buffer_size = buffer_size
self.buffer_size_step = buffer_size_step
self.tracing_path = tracing_path
@ -67,10 +69,13 @@ class FtraceCollector(TraceCollector):
self.start_time = None
self.stop_time = None
self.event_string = _build_trace_events(self.events)
self.function_string = _build_trace_functions(self.functions)
self._reset_needed = True
# Setup tracing paths
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.function_profile_file = self.target.path.join(self.tracing_path, 'function_profile_enabled')
self.marker_file = self.target.path.join(self.tracing_path, 'trace_marker')
self.host_binary = which('trace-cmd')
@ -90,6 +95,18 @@ class FtraceCollector(TraceCollector):
raise TargetError('No trace-cmd found on device and no_install=True is specified.')
self.target_binary = 'trace-cmd'
# Check for function tracing support
if self.functions:
if not self.target.file_exists(self.function_profile_file):
raise TargetError('Function profiling not supported. '\
'A kernel build with CONFIG_FUNCTION_PROFILER enable is required')
# Validate required functions to be traced
available_functions = self.target.execute(
'cat {}'.format(self.available_functions_file)).splitlines()
for function in self.functions:
if function not in available_functions:
raise TargetError('Function [{}] not available for filtering'.format(function))
def reset(self):
if self.buffer_size:
self._set_buffer_size()
@ -205,3 +222,6 @@ def _build_trace_events(events):
event_string = ' '.join(['-e {}'.format(e) for e in events])
return event_string
def _build_trace_functions(functions):
function_string = " ".join(functions)
return function_string