fgraph: Make overruns 4 bytes in graph stack structure

Inspecting the data structures of the function graph tracer, I found that
the overrun value is unsigned long, which is 8 bytes on a 64 bit machine,
and not only that, the depth is an int (4 bytes). The overrun can be simply
an unsigned int (4 bytes) and pack the ftrace_graph_ret structure better.

The depth is moved up next to the func, as it is used more often with func,
and improves cache locality.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

include/linux/ftrace.h

@@ -864,11 +864,11 @@ struct ftrace_graph_ent {
  */
 struct ftrace_graph_ret {
 	unsigned long func; /* Current function */
+	int depth;
 	/* Number of functions that overran the depth limit for current task */
-	unsigned long overrun;
+	unsigned int overrun;
 	unsigned long long calltime;
 	unsigned long long rettime;
-	int depth;
 } __packed;
 
 /* Type of the callback handlers for tracing function graph*/

kernel/trace/trace_entries.h

@@ -93,10 +93,10 @@ FTRACE_ENTRY_PACKED(funcgraph_exit, ftrace_graph_ret_entry,
 	F_STRUCT(
 		__field_struct(	struct ftrace_graph_ret,	ret	)
 		__field_packed(	unsigned long,	ret,		func	)
-		__field_packed(	unsigned long,	ret,		overrun	)
+		__field_packed(	int,		ret,		depth	)
+		__field_packed(	unsigned int,	ret,		overrun	)
 		__field_packed(	unsigned long long, ret,	calltime)
 		__field_packed(	unsigned long long, ret,	rettime	)
-		__field_packed(	int,		ret,		depth	)
 	),
 
 	F_printk("<-- %ps (%d) (start: %llx  end: %llx) over: %d",

kernel/trace/trace_functions_graph.c

@@ -957,7 +957,7 @@ print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
 
 	/* Overrun */
 	if (flags & TRACE_GRAPH_PRINT_OVERRUN)
-		trace_seq_printf(s, " (Overruns: %lu)\n",
+		trace_seq_printf(s, " (Overruns: %u)\n",
 				 trace->overrun);
 
 	print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,