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>

5 files changed, 29 insertions, 8 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 015a3d22cf74..9e0a8d245e55 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -365,6 +365,7 @@ struct ftrace_ret_stack {
         unsigned long ret;
         unsigned long func;
         unsigned long long calltime;
+        unsigned long long subtime;
 };
 
 /*
@@ -376,8 +377,6 @@ extern void return_to_handler(void);
 
 extern int
 ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth);
-extern void
-ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret);
 
 /*
  * Sometimes we don't want to trace a function with the function
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);
 }
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 821bf49771d4..5d1a16cae376 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -255,7 +255,8 @@ static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
 
 /* trace_flags holds trace_options default values */
 unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
-        TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME;
+        TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
+        TRACE_ITER_GRAPH_TIME;
 
 /**
  * trace_wake_up - wake up tasks waiting for trace input
@@ -317,6 +318,7 @@ static const char *trace_options[] = {
         "latency-format",
         "global-clock",
         "sleep-time",
+        "graph-time",
         NULL
 };
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index c66ca3b66050..e3429a8ab059 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -685,6 +685,7 @@ enum trace_iterator_flags {
         TRACE_ITER_LATENCY_FMT          = 0x40000,
         TRACE_ITER_GLOBAL_CLK           = 0x80000,
         TRACE_ITER_SLEEP_TIME           = 0x100000,
+        TRACE_ITER_GRAPH_TIME           = 0x200000,
 };
 
 /*
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 85bba0f018b0..10f6ad7d85f6 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -78,13 +78,14 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth)
         current->ret_stack[index].ret = ret;
         current->ret_stack[index].func = func;
         current->ret_stack[index].calltime = calltime;
+        current->ret_stack[index].subtime = 0;
         *depth = index;
 
         return 0;
 }
 
 /* Retrieve a function return address to the trace stack on thread info.*/
-void
+static void
 ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
 {
         int index;
@@ -104,9 +105,6 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
         trace->calltime = current->ret_stack[index].calltime;
         trace->overrun = atomic_read(&current->trace_overrun);
         trace->depth = index;
-        barrier();
-        current->curr_ret_stack--;
-
 }
 
 /*
@@ -121,6 +119,8 @@ unsigned long ftrace_return_to_handler(void)
         ftrace_pop_return_trace(&trace, &ret);
         trace.rettime = trace_clock_local();
         ftrace_graph_return(&trace);
+        barrier();
+        current->curr_ret_stack--;
 
         if (unlikely(!ret)) {
                 ftrace_graph_stop();