Re: [PATCH v2 09/15] perf ftrace: add support for tracing option 'func_stack_trace'

[Namhyung Kim]

On Sat, Jun 27, 2020 at 10:38 PM Changbin Du <changbin.du@xxxxxxxxx> wrote:
>
> This adds support to display call trace for function tracer. To do this,
> just specify a '--func-call-graph' option.

What if it's used with -G option?  Also it might be used only with
the -T option..  How about showing a warning if it's missing.. ?

Thanks
Namhyung

>
> $ sudo perf ftrace -T vfs_read --func-call-graph
>  iio-sensor-prox-855   [003]   6168.369657: vfs_read <-ksys_read
>  iio-sensor-prox-855   [003]   6168.369677: <stack trace>
>  => vfs_read
>  => ksys_read
>  => __x64_sys_read
>  => do_syscall_64
>  => entry_SYSCALL_64_after_hwframe
>  ...
>
> Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>