[PATCH v2 14/15] perf ftrace: add support for trace option tracing_thresh

[Changbin Du <changbin.du@gmail.com>]

This adds an option '--graph-thresh' to setup trace duration threshold
for funcgraph tracer.

$ sudo ./perf ftrace -G --graph-thresh 100
 3) ! 184.060 us  |    } /* schedule */
 3) ! 185.600 us  |  } /* exit_to_usermode_loop */
 2) ! 225.989 us  |    } /* schedule_idle */
 2) # 4140.051 us |  } /* do_idle */

Signed-off-by: Changbin Du <changbin.du@gmail.com>
---
 tools/perf/Documentation/perf-ftrace.txt |  3 +++
 tools/perf/builtin-ftrace.c              | 25 ++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt
index cc770fc0a1e8..64843d0cdc45 100644
--- a/tools/perf/Documentation/perf-ftrace.txt
+++ b/tools/perf/Documentation/perf-ftrace.txt
@@ -116,6 +116,9 @@ OPTIONS
 --graph-verbose::
 	Show process names, PIDs, timestamps for function_graph tracer.
 
+--graph-thresh::
+	Setup trace duration threshold for funcgraph tracer.
+
 SEE ALSO
 --------
 linkperf:perf-record[1], linkperf:perf-trace[1]
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index e037fe7abd47..0f8716ea0da4 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -46,6 +46,7 @@ struct perf_ftrace {
 	bool			graph_nosleep_time;
 	bool			graph_noirqs;
 	bool			graph_verbose;
+	unsigned		graph_thresh;
 };
 
 struct filter_entry {
@@ -229,6 +230,9 @@ static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
 	if (write_tracing_file("max_graph_depth", "0") < 0)
 		return -1;
 
+	if (write_tracing_file("tracing_thresh", "0") < 0)
+		return -1;
+
 	reset_tracing_filters();
 	reset_tracing_options(ftrace);
 	return 0;
@@ -440,6 +444,20 @@ static int set_tracing_funcgraph_verbose(struct perf_ftrace *ftrace)
 	return 0;
 }
 
+static int set_tracing_thresh(struct perf_ftrace *ftrace)
+{
+	int ret;
+
+	if (ftrace->graph_thresh == 0)
+		return 0;
+
+	ret = write_tracing_file_int("tracing_thresh", ftrace->graph_thresh);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
 static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
 {
 	char *trace_file;
@@ -539,6 +557,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
 		goto out_reset;
 	}
 
+	if (set_tracing_thresh(ftrace) < 0) {
+		pr_err("failed to set tracing thresh\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;
@@ -726,6 +749,8 @@ int cmd_ftrace(int argc, const char **argv)
 		    "ignore functions that happen inside interrupt for function_graph tracer"),
 	OPT_BOOLEAN(0, "graph-verbose", &ftrace.graph_verbose,
 		    "show process names, PIDs, timestamps for function_graph tracer"),
+	OPT_UINTEGER(0, "graph-thresh", &ftrace.graph_thresh,
+		     "only show functions of which the duration is greater than <n>µs"),
 	OPT_END()
 	};
 
-- 
2.25.1