[PATCH 21/23] perf ftrace: Add -D option for depth filter

Arnaldo Carvalho de Melo
2017-06-20T01:58:33Z

From: Namhyung Kim <namhyung@kernel.org>

The -D/--graph-depth option is to set max graph depth. The following
example traces max 2-depth of page fault handler.

$ sudo perf ftrace -G __do_page_fault -D 2 -- hello
...
0) | __do_page_fault() {
0) 0.063 us | down_read_trylock();
0) 0.251 us | find_vma();
0) 5.374 us | handle_mm_fault();
0) 0.054 us | up_read();
0) 7.463 us | }
...

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: kernel-team@lge.com
Link: http://lkml.kernel.org/r/20170618142302.25390-4-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Documentation/perf-ftrace.txt | 3 +++
tools/perf/builtin-ftrace.c | 31 +++++++++++++++++++++++++++++++
2 files changed, 34 insertions(+)

diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt
index 78d6126ca485..721a447f046e 100644
--- a/tools/perf/Documentation/perf-ftrace.txt
+++ b/tools/perf/Documentation/perf-ftrace.txt
@@ -78,6 +78,9 @@ OPTIONS
This can be used more than once to specify multiple functions.
It will be passed to 'set_graph_notrace' in tracefs.

+-D::
+--graph-depth=::
+ Set max depth for function graph tracer to follow

SEE ALSO
--------
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 3285375ce3c2..dd26c62c9893 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -35,6 +35,7 @@ struct perf_ftrace {
struct list_head notrace;
struct list_head graph_funcs;
struct list_head nograph_funcs;
+ int graph_depth;
};

struct filter_entry {
@@ -129,6 +130,9 @@ static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
if (reset_tracing_cpu() < 0)
return -1;

+ if (write_tracing_file("max_graph_depth", "0") < 0)
+ return -1;
+
reset_tracing_filters();
return 0;
}
@@ -237,6 +241,26 @@ static void reset_tracing_filters(void)
write_tracing_file("set_graph_notrace", " ");
}

+static int set_tracing_depth(struct perf_ftrace *ftrace)
+{
+ char buf[16];
+
+ if (ftrace->graph_depth == 0)
+ return 0;
+
+ if (ftrace->graph_depth < 0) {
+ pr_err("invalid graph depth: %d\n", ftrace->graph_depth);
+ return -1;
+ }
+
+ snprintf(buf, sizeof(buf), "%d", ftrace->graph_depth);
+
+ if (write_tracing_file("max_graph_depth", buf) < 0)
+ return -1;
+
+ return 0;
+}
+
static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
{
char *trace_file;
@@ -284,6 +308,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
goto out_reset;
}

+ if (set_tracing_depth(ftrace) < 0) {
+ pr_err("failed to set graph depth\n");
+ goto out_reset;
+ }
+
if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
pr_err("failed to set current_tracer to %s\n", ftrace->tracer);
goto out_reset;
@@ -425,6 +454,8 @@ int cmd_ftrace(int argc, const char **argv)
"Set graph filter on given functions", 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,
+ "Max depth for function graph tracer"),
OPT_END()
};

--
2.9.4