function-graph: add option to calculate graph time or not

graph time is the time that a function is executing another function.
Thus if function A calls B, if graph-time is set, then the time for
A includes B. This is the default behavior. But if graph-time is off,
then the time spent executing B is subtracted from A.

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

1 files changed, 20 insertions, 1 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index ed1fc5021d44..71e5faef12ab 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -604,6 +604,7 @@ static int profile_graph_entry(struct ftrace_graph_ent *trace)
 static void profile_graph_return(struct ftrace_graph_ret *trace)
 {
         struct ftrace_profile_stat *stat;
+        unsigned long long calltime;
         struct ftrace_profile *rec;
         unsigned long flags;
 
@@ -612,9 +613,27 @@ static void profile_graph_return(struct ftrace_graph_ret *trace)
         if (!stat->hash)
                 goto out;
 
+        calltime = trace->rettime - trace->calltime;
+
+        if (!(trace_flags & TRACE_ITER_GRAPH_TIME)) {
+                int index;
+
+                index = trace->depth;
+
+                /* Append this call time to the parent time to subtract */
+                if (index)
+                        current->ret_stack[index - 1].subtime += calltime;
+
+                if (current->ret_stack[index].subtime < calltime)
+                        calltime -= current->ret_stack[index].subtime;
+                else
+                        calltime = 0;
+        }
+
         rec = ftrace_find_profiled_func(stat, trace->func);
         if (rec)
-                rec->time += trace->rettime - trace->calltime;
+                rec->time += calltime;
+
  out:
         local_irq_restore(flags);
 }