tracing/function-graph-tracer: implement a print_headers function

Impact: provide trace headers to explain a bit the output

This patch implements the print_headers callback for the function graph
tracer. These headers are output according to the current trace options.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 29 insertions, 4 deletions

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 32b7fb9a19df..af60eef4cbcc 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -570,11 +570,36 @@ print_graph_function(struct trace_iterator *iter)
         }
 }
 
+static void print_graph_headers(struct seq_file *s)
+{
+        /* 1st line */
+        seq_printf(s, "# ");
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
+                seq_printf(s, "CPU ");
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
+                seq_printf(s, "TASK/PID     ");
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD)
+                seq_printf(s, "OVERHEAD/");
+        seq_printf(s, "DURATION            FUNCTION CALLS\n");
+
+        /* 2nd line */
+        seq_printf(s, "# ");
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
+                seq_printf(s, "|   ");
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
+                seq_printf(s, "|      |     ");
+        if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
+                seq_printf(s, "|        ");
+                seq_printf(s, "|                   |   |   |   |\n");
+        } else
+                seq_printf(s, "    |               |   |   |   |\n");
+}
 static struct tracer graph_trace __read_mostly = {
-        .name        = "function_graph",
-        .init        = graph_trace_init,
-        .reset       = graph_trace_reset,
-        .print_line = print_graph_function,
+        .name           = "function_graph",
+        .init           = graph_trace_init,
+        .reset          = graph_trace_reset,
+        .print_line     = print_graph_function,
+        .print_header   = print_graph_headers,
         .flags          = &tracer_flags,
 };