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>

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 3925ec0184b1dcd2fb1aa5b8af51567677a820be..a85da1764b1c3ff7eb10494b53694fd499683f78 100644 (file)
--- 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 1f69ac7c158778292a126ef4bae5ffad61375c47..6ea62acbe4b600f8cf6b3453b6e19207aa227f3a 100644 (file)
--- 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 c009553a8e815829cc47658744868d86d66e2d32..e527f2f66c73653cbe3c106e6a7b52a40074db00 100644 (file)
--- 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)) {