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ftrace: force report CPU frequencies at trace start and stop

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When the cpufreq module is loaded, quite likely we want to run experiments
which involve an analysis of frequencies transitions. However, if during
an experiment there are not cpu_frequency events, the generated trace
does not allows to know at which frequency the experiment has been executed.
This happens for example when we are running at constant frequency or just
because the workload is not generating a variable capacity request in the
system.

This path ensure the a "cpu_frequency" events is always generated at the
beginning and at the end of a collected trace. This support is required
for example to properly plot CPUs frequencies event when there are not
CPUFreq generated changes of OPP.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
This commit is contained in:
Patrick Bellasi 2015-11-16 17:45:33 +00:00
parent 701e6adf7a
commit a7cfd28bd0
1 changed files with 6 additions and 0 deletions
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6
devlib/trace/ftrace.py
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@ -101,8 +101,14 @@ class FtraceCollector(TraceCollector):
if self.automark:
self.mark_start()
self.target.execute('{} start {}'.format(self.target_binary, self.event_string), as_root=True)
if 'cpufreq' in self.target.modules:
self.logger.debug('Trace CPUFreq frequencies')
self.target.cpufreq.trace_frequencies()
def stop(self):
if 'cpufreq' in self.target.modules:
self.logger.debug('Trace CPUFreq frequencies')
self.target.cpufreq.trace_frequencies()
self.stop_time = time.time()
if self.automark:
self.mark_stop()