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>

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 8061963..8dde9c1 100644 (file)
--- a/include/linux/ftrace.h
+++ b/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*/

diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
index 18c4a58..ceafe2d 100644 (file)
--- a/kernel/trace/trace_entries.h
+++ b/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",

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 60d6627..d874dec 100644 (file)
--- a/kernel/trace/trace_functions_graph.c
+++ b/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,