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ftrace: Allow setting the number of cmdlines saved by ftrace

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While tracing, ftrace records a mapping of PIDs to cmdlines. By default, it will
only record up to 128 such entries, which is not enough for a typical android
system. The consequence is trace-cmd reporting "<...>" as cmdline.

Allow setting that number to a higher value, and default to a comfortable 4096
entries.

Signed-off-by: Douglas RAILLARD <douglas.raillard@arm.com>
This commit is contained in:
Douglas RAILLARD 2019-10-31 17:42:16 +00:00 committed by Marc Bonnici
parent def235064b
commit 56cdc2e6c3
1 changed files with 4 additions and 0 deletions
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4
devlib/trace/ftrace.py
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@ -64,6 +64,7 @@ class FtraceCollector(TraceCollector):
strict=False,
report_on_target=False,
trace_clock='local',
saved_cmdlines_nr=4096,
):
super(FtraceCollector, self).__init__(target)
self.events = events if events is not None else DEFAULT_EVENTS
@ -85,6 +86,7 @@ class FtraceCollector(TraceCollector):
self.event_string = None
self.function_string = None
self.trace_clock = trace_clock
self.saved_cmdlines_nr = saved_cmdlines_nr
self._reset_needed = True
# pylint: disable=bad-whitespace
@ -97,6 +99,7 @@ class FtraceCollector(TraceCollector):
self.marker_file = self.target.path.join(self.tracing_path, 'trace_marker')
self.ftrace_filter_file = self.target.path.join(self.tracing_path, 'set_ftrace_filter')
self.trace_clock_file = self.target.path.join(self.tracing_path, 'trace_clock')
self.save_cmdlines_size_file = self.target.path.join(self.tracing_path, 'saved_cmdlines_size')
self.host_binary = which('trace-cmd')
self.kernelshark = which('kernelshark')
@ -175,6 +178,7 @@ class FtraceCollector(TraceCollector):
self.reset()
self.target.write_value(self.trace_clock_file, self.trace_clock, verify=False)
self.target.write_value(self.save_cmdlines_size_file, self.saved_cmdlines_nr)
self.target.execute('{} start {}'.format(self.target_binary, self.event_string),
as_root=True)
if self.automark: