tracing/function-graph-tracer: use the more lightweight local clock

Impact: decrease hangs risks with the graph tracer on slow systems

Since the function graph tracer can spend too much time on timer
interrupts, it's better now to use the more lightweight local
clock. Anyway, the function graph traces are more reliable on a
per cpu trace.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <49af243d.06e9300a.53ad.ffff840c@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 9 insertions, 8 deletions

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 3925ec0184b1..a85da1764b1c 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -436,7 +436,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
                 return;
         }
 
-        calltime = cpu_clock(raw_smp_processor_id());
+        calltime = trace_clock_local();
 
         if (ftrace_push_return_trace(old, calltime,
                                 self_addr, &trace.depth) == -EBUSY) {
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 1f69ac7c1587..6ea62acbe4b6 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1,15 +1,16 @@
 #ifndef _LINUX_FTRACE_H
 #define _LINUX_FTRACE_H
 
-#include <linux/linkage.h>
-#include <linux/fs.h>
-#include <linux/ktime.h>
-#include <linux/init.h>
-#include <linux/types.h>
-#include <linux/module.h>
+#include <linux/trace_clock.h>
 #include <linux/kallsyms.h>
+#include <linux/linkage.h>
 #include <linux/bitops.h>
+#include <linux/module.h>
+#include <linux/ktime.h>
 #include <linux/sched.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/fs.h>
 
 #include <asm/ftrace.h>
 
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index c009553a8e81..e527f2f66c73 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -112,7 +112,7 @@ unsigned long ftrace_return_to_handler(void)
         unsigned long ret;
 
         ftrace_pop_return_trace(&trace, &ret);
-        trace.rettime = cpu_clock(raw_smp_processor_id());
+        trace.rettime = trace_clock_local();
         ftrace_graph_return(&trace);
 
         if (unlikely(!ret)) {