Re: [PATCH v3 00/27] function_graph: Allow multiple users for function graph tracing

Steven Rostedt
2024-06-04T18:57:45Z

On Tue, 4 Jun 2024 18:04:22 +0100
Mark Rutland <mark.rutland@arm.com> wrote:

> > There may have been something arch specific that I'm unaware about. I'll
> > look at that deeper.
>
> It looks like e are lines in the trace that it doesn't expect:
>
> + cat trace
> + grep -v ^#
> + grep 970
> + wc -l
> + count_pid=0
> + cat trace
> + grep -v ^#
> + grep -v 970
> + wc -l
> + count_other=3
> + [ 0 -eq 0 -o 3 -ne 0 ]
> + fail PID filtering not working?
>
> ... where we expect that count_other to be 0.
>
> I hacked in a 'cat trace' just before the 'fail' and that shows:
>
> + cat trace
> # tracer: function_graph
> #
> # CPU DURATION FUNCTION CALLS
> # | | | | | | |
> 3) ! 143.685 us | kernel_clone();
> 3) ! 127.055 us | kernel_clone();
> 1) ! 127.170 us | kernel_clone();
> 3) ! 126.840 us | kernel_clone();
>
> I'm not sure if that's legitimate output the test is failing to account
> for or if that indicates a kernel-side issue.

Bah, I just ran the test.d/ftrace/func-filter-pid.tc and it fails too. This
did pass my other tests that do run ftracetests. Hmm, I just ran it on my
test box that does the tests and it passes there. I wonder if there's some
config option that makes it fail :-/

Well, now that I see it fail, I can investigate.

-- Steve