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[PATCH 1/3] tracing: Prevent wasting time evaluating parameters in trace_preempt_on/off

 

 

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rostedt at goodmis

May 9, 2012, 9:57 AM

Post #1 of 1 (60 views)
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[PATCH 1/3] tracing: Prevent wasting time evaluating parameters in trace_preempt_on/off

From: Minho Ban <mhban [at] samsung>

This fixes spending time for evaluating parameters in trace_preempt_on/off when
the tracer config is off.

The patch mainly inspired by Steven Rostedt, thanks Steven.

Link: http://lkml.kernel.org/r/4FA73510.7070705 [at] samsung

Cc: Ingo Molnar <mingo [at] redhat>
Cc: Frederic Weisbecker <fweisbec [at] gmail>
Cc: Peter Zijlstra <a.p.zijlstra [at] chello>
Cc: Paul Turner <pjt [at] google>
Cc: Thomas Gleixner <tglx [at] linutronix>
Cc: Hidetoshi Seto <seto.hidetoshi [at] jp>
Cc: Paul E. McKenney <paulmck [at] linux>
Cc: Josh Triplett <josh [at] joshtriplett>
Signed-off-by: Minho Ban <mhban [at] samsung>
Signed-off-by: Steven Rostedt <rostedt [at] goodmis>
---
include/linux/ftrace.h | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 0b55903..d32cc5e 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -491,8 +491,12 @@ static inline void __ftrace_enabled_restore(int enabled)
extern void trace_preempt_on(unsigned long a0, unsigned long a1);
extern void trace_preempt_off(unsigned long a0, unsigned long a1);
#else
- static inline void trace_preempt_on(unsigned long a0, unsigned long a1) { }
- static inline void trace_preempt_off(unsigned long a0, unsigned long a1) { }
+/*
+ * Use defines instead of static inlines because some arches will make code out
+ * of the CALLER_ADDR, when we really want these to be a real nop.
+ */
+# define trace_preempt_on(a0, a1) do { } while (0)
+# define trace_preempt_off(a0, a1) do { } while (0)
#endif

#ifdef CONFIG_FTRACE_MCOUNT_RECORD
--
1.7.10
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