I've tried these, but all of them produce "empty" output files:
trace-cmd record -p function_graph -g munmap -F ls
trace-cmd record -p function_graph -g sys_enter_munmap -F ls
trace-cmd record -p function_graph -g sys_enter -F ls
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Are you sure ftrace is enabled?em_and_m– em_and_m2011-04-09 17:49:01 +00:00Commented Apr 9, 2011 at 17:49
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Yeah, it works if I just tell it to dump all events.Robin Green– Robin Green2011-04-09 19:09:48 +00:00Commented Apr 9, 2011 at 19:09
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Well, I tried these and they work here (Ubuntu 2.6.35-28,trace-cmd version 1.0.3 ) so I would guess the problem lies in your specific kernel or ftrace-cmd version and/or config.em_and_m– em_and_m2011-04-10 06:58:11 +00:00Commented Apr 10, 2011 at 6:58
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What command did you use to view the output? What kind of output did you get?Robin Green– Robin Green2011-04-10 07:05:28 +00:00Commented Apr 10, 2011 at 7:05
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1hmm... seems something is fishy indeed. I tried now the command: " trace-cmd record -p function_graph -g xxx -F ls " And it seems to produce the same output. I don't think the filtering works... :-)em_and_m– em_and_m2011-04-10 07:37:36 +00:00Commented Apr 10, 2011 at 7:37
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1 Answer
First you need to get the function name right - e.g. the function name to use for tracing open syscalls is sys_open.
To do this the "proper" way, it's necessary to have function_graph support in the kernel. On the x86 architecture this depends on CC_OPTIMIZE_FOR_SIZE being disabled, but on x86_64 it doesn't.
In my case I didn't bother to compile a custom kernel to disable CC_OPTIMIZE_FOR_SIZE, I just did
trace-cmd record -p function --func-stack
and included various functions that looked like they might be called by adding several -l options. This was enough to figure out what I wanted to know.