linux-kernel - [tip:perf/core] tracing: Prevent wasting time evaluating parameters in trace_preempt

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Date:	Thu, 10 May 2012 01:55:41 -0700
From:	tip-bot for Minho Ban <mhban@...sung.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...hat.com, linux-kernel@...r.kernel.org, hpa@...or.com,
	mingo@...nel.org, seto.hidetoshi@...fujitsu.com,
	a.p.zijlstra@...llo.nl, pjt@...gle.com, paulmck@...ux.vnet.ibm.com,
	fweisbec@...il.com, rostedt@...dmis.org, mhban@...sung.com,
	josh@...htriplett.org, tglx@...utronix.de
Subject: [tip:perf/core] tracing:
  Prevent wasting time evaluating parameters in trace_preempt_on/off

Commit-ID:  b02ee9a33b65bcc4ad13c12a0b04afdaab3ddd8d
Gitweb:     http://git.kernel.org/tip/b02ee9a33b65bcc4ad13c12a0b04afdaab3ddd8d
Author:     Minho Ban <mhban@...sung.com>
AuthorDate: Mon, 7 May 2012 11:36:00 +0900
Committer:  Steven Rostedt <rostedt@...dmis.org>
CommitDate: Tue, 8 May 2012 09:33:52 -0400

tracing: Prevent wasting time evaluating parameters in trace_preempt_on/off

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@samsung.com

Cc: Ingo Molnar <mingo@...hat.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Turner <pjt@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Josh Triplett <josh@...htriplett.org>
Signed-off-by: Minho Ban <mhban@...sung.com>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
---
 include/linux/ftrace.h |    8 ++++++--
 1 files 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
--
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