linux-kernel - Re: [PATCH 11/19] perf ftrace: add option '-u/--userstacktrace' to show userspace stacktrace

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Date:   Wed, 20 May 2020 18:07:41 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Changbin Du <changbin.du@...il.com>
Cc:     Jiri Olsa <jolsa@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/19] perf ftrace: add option '-u/--userstacktrace' to
 show userspace stacktrace

Em Sun, May 10, 2020 at 11:06:20PM +0800, Changbin Du escreveu:
> This adds an option ''-u/--userstacktrace' for function tracer to display
> userspace back trace.

Probably we should have this as a term, an option to --call-graph?

For --call-graph the way to suppress this is to ask for the event to be
in the kernel only, i.e. something like:

	perf record -e cycles:k --call-graph

So perhaps we should have something like:

	perf ftrace --call-graph 

With some default, possibly a bit different than the other perf tools,
just including the kernel, and accepting:

	perf ftrace --call-graph
	perf ftrace --call-graph k
	perf ftrace --call-graph u
	perf ftrace --call-graph uk

- Arnaldo
 
> Signed-off-by: Changbin Du <changbin.du@...il.com>
> ---
>  tools/perf/builtin-ftrace.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index 2ef5d1c4b23c..ab76ba66bd9e 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -40,6 +40,7 @@ struct perf_ftrace {
>  	struct list_head	nograph_funcs;
>  	int			graph_depth;
>  	bool			func_stack_trace;
> +	bool			userstacktrace;
>  	bool			nosleep_time;
>  	bool			nofuncgraph_irqs;
>  	bool			funcgraph_tail;
> @@ -197,6 +198,8 @@ static void reset_tracing_options(struct perf_ftrace *ftrace __maybe_unused)
>  	write_tracing_option_file("funcgraph-proc", "0");
>  	write_tracing_option_file("funcgraph-abstime", "0");
>  	write_tracing_option_file("irq-info", "0");
> +	write_tracing_option_file("userstacktrace", "0");
> +	write_tracing_option_file("sym-userobj", "0");
>  }
>  
>  static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
> @@ -287,6 +290,20 @@ static int set_tracing_func_stack_trace(struct perf_ftrace *ftrace)
>  	return 0;
>  }
>  
> +static int set_tracing_userstacktrace(struct perf_ftrace *ftrace)
> +{
> +	if (!ftrace->userstacktrace)
> +		return 0;
> +
> +	if (write_tracing_option_file("userstacktrace", "1") < 0)
> +		return -1;
> +
> +	if (write_tracing_option_file("sym-userobj", "1") < 0)
> +		return -1;
> +
> +	return 0;
> +}
> +
>  static int reset_tracing_cpu(void)
>  {
>  	struct perf_cpu_map *cpumap = perf_cpu_map__new(NULL);
> @@ -482,6 +499,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
>  		goto out_reset;
>  	}
>  
> +	if (set_tracing_userstacktrace(ftrace) < 0) {
> +		pr_err("failed to set tracing option userstacktrace\n");
> +		goto out_reset;
> +	}
> +
>  	if (set_tracing_filters(ftrace) < 0) {
>  		pr_err("failed to set tracing filters\n");
>  		goto out_reset;
> @@ -644,6 +666,8 @@ int cmd_ftrace(int argc, const char **argv)
>  		     "do not trace given functions", parse_filter_func),
>  	OPT_BOOLEAN('s', "func-stack-trace", &ftrace.func_stack_trace,
>  		    "Show kernel stack trace for function tracer"),
> +	OPT_BOOLEAN('u', "userstacktrace", &ftrace.userstacktrace,
> +		    "Show stacktrace of the current user space thread"),
>  	OPT_CALLBACK_DEFAULT('G', "graph-funcs", &ftrace.graph_funcs, "func",
>  		     "Set graph filter on given functions (imply to use function_graph tracer)",
>  		     parse_filter_func, "*"),
> -- 
> 2.25.1
> 

-- 

- Arnaldo