tracing: adding function timings to function profiler

If the function graph trace is enabled, the function profiler will
use it to take the timing of the functions.

 cat /debug/tracing/trace_stat/functions

  Function                               Hit    Time
  --------                               ---    ----
  mwait_idle                             127    183028.4 us
  schedule                                26    151997.7 us
  __schedule                              31    151975.1 us
  sys_wait4                                2    74080.53 us
  do_wait                                  2    74077.80 us
  sys_newlstat                           138    39929.16 us
  do_path_lookup                         179    39845.79 us
  vfs_lstat_fd                           138    39761.97 us
  user_path_at                           153    39469.58 us
  path_walk                              179    39435.76 us
  __link_path_walk                       189    39143.73 us
[...]

Note the times are skewed due to the function graph tracer not taking
into account schedules.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

1 files changed, 14 insertions, 3 deletions

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index d28687e7b3a7..85bba0f018b0 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -426,8 +426,8 @@ print_graph_irq(struct trace_iterator *iter, unsigned long addr,
         return TRACE_TYPE_HANDLED;
 }
 
-static enum print_line_t
-print_graph_duration(unsigned long long duration, struct trace_seq *s)
+enum print_line_t
+trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
 {
         unsigned long nsecs_rem = do_div(duration, 1000);
         /* log10(ULONG_MAX) + '\0' */
@@ -464,12 +464,23 @@ print_graph_duration(unsigned long long duration, struct trace_seq *s)
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
         }
+        return TRACE_TYPE_HANDLED;
+}
+
+static enum print_line_t
+print_graph_duration(unsigned long long duration, struct trace_seq *s)
+{
+        int ret;
+
+        ret = trace_print_graph_duration(duration, s);
+        if (ret != TRACE_TYPE_HANDLED)
+                return ret;
 
         ret = trace_seq_printf(s, "|  ");
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;
-        return TRACE_TYPE_HANDLED;
 
+        return TRACE_TYPE_HANDLED;
 }
 
 /* Case of a leaf function on its call entry */