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References: <20200627133654.64863-1-changbin.du@gmail.com> <20200627133654.64863-10-changbin.du@gmail.com>
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From:   Namhyung Kim <namhyung@kernel.org>
Date:   Fri, 3 Jul 2020 15:30:32 +0900
Message-ID: <CAM9d7ch7gPmen8TJ9PbiK-QnQ_ojGVGqbR3bGYT4AMNW3Odp+A@mail.gmail.com>
Subject: Re: [PATCH v2 09/15] perf ftrace: add support for tracing option 'func_stack_trace'
To:     Changbin Du <changbin.du@gmail.com>
Cc:     Jiri Olsa <jolsa@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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On Sat, Jun 27, 2020 at 10:38 PM Changbin Du <changbin.du@gmail.com> 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@gmail.com>