On Sat, Jul 11, 2020 at 9:42 PM Changbin Du <changbin...@gmail.com> wrote:
>
> This adds an option '--inherit' to allow us trace children
> processes spawned by our target.
>
> Signed-off-by: Changbin Du <changbin...@gmail.com>
>
> ---
> v2: option name '--trace-children' -> '--inherit'.
> ---
> tools/perf/Documentation/perf-ftrace.txt | 3 ++
> tools/perf/builtin-ftrace.c | 38 ++++++++++++++++++++++++
> 2 files changed, 41 insertions(+)
>
> diff --git a/tools/perf/Documentation/perf-ftrace.txt
> b/tools/perf/Documentation/perf-ftrace.txt
> index 98fe01d354d1..fd632bd9b2c1 100644
> --- a/tools/perf/Documentation/perf-ftrace.txt
> +++ b/tools/perf/Documentation/perf-ftrace.txt
> @@ -61,6 +61,9 @@ OPTIONS
> Set the size of per-cpu tracing buffer, <size> is expected to
> be a number with appended unit character - B/K/M/G.
>
> +--inherit::
> + Trace children processes spawned by our target.
> +
> -T::
> --trace-funcs=::
> Only trace functions given by the argument. Multiple functions
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index 887e78b23a82..4efaa7b6a906 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -39,6 +39,7 @@ struct perf_ftrace {
> struct list_head nograph_funcs;
> int graph_depth;
> unsigned long percpu_buffer_size;
> + bool inherit;
> };
>
> struct filter_entry {
> @@ -177,9 +178,27 @@ static int write_tracing_file_int(const char *name, int
> value)
> return 0;
> }
>
> +static int write_tracing_option_file(const char *name, const char *val)
> +{
> + char *file;
> + int ret;
> +
> + if (asprintf(&file, "options/%s", name) < 0)
> + return -1;
> +
> + ret = __write_tracing_file(file, val, false);
> + free(file);
> + return ret;
> +}
> +
> static int reset_tracing_cpu(void);
> static void reset_tracing_filters(void);
>
> +static void reset_tracing_options(struct perf_ftrace *ftrace __maybe_unused)
> +{
> + write_tracing_option_file("function-fork", "0");
> +}
> +
> static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
> {
> if (write_tracing_file("tracing_on", "0") < 0)
> @@ -198,6 +217,7 @@ static int reset_tracing_files(struct perf_ftrace *ftrace
> __maybe_unused)
> return -1;
>
> reset_tracing_filters();
> + reset_tracing_options(ftrace);
> return 0;
> }
>
> @@ -336,6 +356,17 @@ static int set_tracing_percpu_buffer_size(struct
> perf_ftrace *ftrace)
> return 0;
> }
>
> +static int set_tracing_trace_inherit(struct perf_ftrace *ftrace)
> +{
> + if (!ftrace->inherit)
> + return 0;
> +
> + if (write_tracing_option_file("function-fork", "1") < 0)
> + return -1;
> +
> + return 0;
> +}
> +
> static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char
> **argv)
> {
> char *trace_file;
> @@ -405,6 +436,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int
> argc, const char **argv)
> goto out_reset;
> }
>
> + if (set_tracing_trace_inherit(ftrace) < 0) {
> + pr_err("failed to set tracing option function-fork\n");
> + goto out_reset;
> + }
Can we have set_tracing_options() here instead to make
the __cmd_ftrace() shorter? It'd set other options added later.
It's also symmetric to reset_tracing_options().
Thanks
Namhyung
> +
> if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
> pr_err("failed to set current_tracer to %s\n",
> ftrace->tracer);
> goto out_reset;
> @@ -599,6 +635,8 @@ int cmd_ftrace(int argc, const char **argv)
> "Max depth for function graph tracer"),
> OPT_CALLBACK('m', "buffer-size", &ftrace.percpu_buffer_size, "size",
> "size of per cpu buffer", parse_buffer_size),
> + OPT_BOOLEAN(0, "inherit", &ftrace.inherit,
> + "trace children processes"),
> OPT_END()
> };
>
> --
> 2.25.1
>
