Steven Rostedt (Red Hat) 951dbf500a ftrace/scripts: Add helper script to bisect function tracing problem functions ... Every so often, with a special config or a architecture change, running function or function_graph tracing can cause the machien to hard reboot, crash, or simply hard lockup. There's some functions in the function graph tracer that can not be traced otherwise it causes the function tracer to recurse before the recursion protection mechanisms are in place. When this occurs, using the dynamic ftrace featuer that allows limiting what actually gets traced can be used to bisect down to the problem function. This adds a script that helps with this process in the scripts/tracing directory, called ftrace-bisect.sh The set up is to read all the functions that can be traced from available_filter_functions into a file (full_file). Then run this script passing it the full_file and a "test_file" and "non_test_file", where the test_file will be add to set_ftrace_filter. What ftarce_bisect.sh does, is to copy half of the functions in full_file into the test_file and the other half into the non_test_file. This way, one can cat the test_file into the set_ftrace_filter functions and only test the functions that are in that file. If it works, then we run the process again after copying non_test_file to full_file and repeating the process. If the system crashed, then the bad function is in the test_file and after a reboot, the test_file becomes the new full_file in the next iteration. When we get down to a single function in the full_file, then ftrace_bisect.sh will report that as the bad function. Full documentation of how to use this simple script is within the script file itself. Link: http://lkml.kernel.org/r/20160920100716.131d3647@gandalf.local.home Signed-off-by: Steven Rostedt <rostedt@goodmis.org>		2016-09-21 13:56:55 -04:00
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draw_functrace.py
ftrace-bisect.sh	ftrace/scripts: Add helper script to bisect function tracing problem functions	2016-09-21 13:56:55 -04:00