Commit eb6d31ae authored by Changbin Du's avatar Changbin Du Committed by Arnaldo Carvalho de Melo
Browse files

perf ftrace: Select function/function_graph tracer automatically 



The '-g/-G' options have already implied function_graph tracer should be
used instead of function tracer. So we don't need extra option
'--tracer' in this case.

This patch changes the behavior as below:

  - If '-g' or '-G' option is on, then function_graph tracer is used.
  - If '-T' or '-N' option is on, then function tracer is used.
  - The function_graph has priority over function tracer.
  - The option '--tracer' only take effect if neither -g/-G nor -T/-N
    is specified.

Here are some examples.

This will start tracing all functions using default tracer:

  $ sudo perf ftrace

This will trace all functions using function graph tracer:

  $ sudo perf ftrace -G '*'

This will trace function vfs_read using function graph tracer:

  $ sudo perf ftrace -G vfs_read

This will trace function vfs_read using function tracer:

  $ sudo perf ftrace -T vfs_read

Committer notes:

Using '-h -G' will tell what that option is about, so to further clarify
the above examples:

  # perf ftrace -h -G

    -G, --graph-funcs <func>	Set graph filter on given functions

  # perf ftrace -h -g

    -g, --nograph-funcs <func>	Set nograph filter on given functions

  # perf ftrace -h -T

    -T, --trace-funcs <func>	trace given functions only

  # perf ftrace -h -N

    -N, --notrace-funcs <func>	do not trace given functions

  #

Signed-off-by: default avatarChangbin Du <changbin.du@gmail.com>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: http://lore.kernel.org/lkml/20200808023141.14227-2-changbin.du@gmail.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 2db13a9b

tools/perf/Documentation/perf-config.txt

+3 −2
Original line number Diff line number Diff line
@@ -614,8 +614,9 @@ trace.*:: 


ftrace.*::

	ftrace.tracer::

		Can be used to select the default tracer. Possible values are

		'function' and 'function_graph'.

		Can be used to select the default tracer when neither -G nor

		-F option is not specified. Possible values are 'function' and

		'function_graph'.



llvm.*::

	llvm.clang-path::

tools/perf/Documentation/perf-ftrace.txt

+22 −19
Original line number Diff line number Diff line
@@ -24,7 +24,8 @@ OPTIONS 


-t::

--tracer=::

	Tracer to use: function_graph or function.

	Tracer to use when neither -G nor -F option is not

	specified: function_graph or function.



-v::

--verbose=::
@@ -50,33 +51,35 @@ OPTIONS 


-T::

--trace-funcs=::

	Only trace functions given by the argument.  Multiple functions

	can be given by using this option more than once.  The function

	argument also can be a glob pattern.  It will be passed to

	'set_ftrace_filter' in tracefs.

	Select function tracer and set function filter on the given

	function (or a glob pattern). Multiple functions can be given

	by using this option more than once. The function argument also

	can be a glob pattern. It will be passed to 'set_ftrace_filter'

	in tracefs.



-N::

--notrace-funcs=::

	Do not trace functions given by the argument.  Like -T option,

	this can be used more than once to specify multiple functions

	(or glob patterns).  It will be passed to 'set_ftrace_notrace'

	in tracefs.

	Select function tracer and do not trace functions given by the

	argument.  Like -T option, this can be used more than once to

	specify multiple functions (or glob patterns).  It will be

	passed to 'set_ftrace_notrace' in tracefs.



-G::

--graph-funcs=::

	Set graph filter on the given function (or a glob pattern).

	This is useful for the function_graph tracer only and enables

	tracing for functions executed from the given function.

	This can be used more than once to specify multiple functions.

	It will be passed to 'set_graph_function' in tracefs.

	Select function_graph tracer and set graph filter on the given

	function (or a glob pattern). This is useful to trace for

	functions executed from the given function. This can be used more

	than once to specify multiple functions. It will be passed to

	'set_graph_function' in tracefs.



-g::

--nograph-funcs=::

	Set graph notrace filter on the given function (or a glob pattern).

	Like -G option, this is useful for the function_graph tracer only

	and disables tracing for function executed from the given function.

	This can be used more than once to specify multiple functions.

	It will be passed to 'set_graph_notrace' in tracefs.

	Select function_graph tracer and set graph notrace filter on the

	given function (or a glob pattern). Like -G option, this is useful

	for the function_graph tracer only and disables tracing for function

	executed from the given function. This can be used more than once to

	specify multiple functions. It will be passed to 'set_graph_notrace'

	in tracefs.



-D::

--graph-depth=::

tools/perf/builtin-ftrace.c

+23 −2
Original line number Diff line number Diff line
@@ -455,6 +455,23 @@ static void delete_filter_func(struct list_head *head) 
	}

}



static void select_tracer(struct perf_ftrace *ftrace)

{

	bool graph = !list_empty(&ftrace->graph_funcs) ||

		     !list_empty(&ftrace->nograph_funcs);

	bool func = !list_empty(&ftrace->filters) ||

		    !list_empty(&ftrace->notrace);



	/* The function_graph has priority over function tracer. */

	if (graph)

		ftrace->tracer = "function_graph";

	else if (func)

		ftrace->tracer = "function";

	/* Otherwise, the default tracer is used. */



	pr_debug("%s tracer is used\n", ftrace->tracer);

}



int cmd_ftrace(int argc, const char **argv)

{

	int ret;
@@ -479,11 +496,13 @@ int cmd_ftrace(int argc, const char **argv) 
	OPT_STRING('C', "cpu", &ftrace.target.cpu_list, "cpu",

		    "list of cpus to monitor"),

	OPT_CALLBACK('T', "trace-funcs", &ftrace.filters, "func",

		     "trace given functions only", parse_filter_func),

		     "trace given functions using function tracer",

		     parse_filter_func),

	OPT_CALLBACK('N', "notrace-funcs", &ftrace.notrace, "func",

		     "do not trace given functions", parse_filter_func),

	OPT_CALLBACK('G', "graph-funcs", &ftrace.graph_funcs, "func",

		     "Set graph filter on given functions", parse_filter_func),

		     "trace given functions using function_graph tracer",

		     parse_filter_func),

	OPT_CALLBACK('g', "nograph-funcs", &ftrace.nograph_funcs, "func",

		     "Set nograph filter on given functions", parse_filter_func),

	OPT_INTEGER('D', "graph-depth", &ftrace.graph_depth,
@@ -505,6 +524,8 @@ int cmd_ftrace(int argc, const char **argv) 
	if (!argc && target__none(&ftrace.target))

		ftrace.target.system_wide = true;



	select_tracer(&ftrace);



	ret = target__validate(&ftrace.target);

	if (ret) {

		char errbuf[512];

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