linux-kernel - [tip:perfcounters/core] tracing, x86, cpuidle: Move the end point of a C state in the power tracer

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Message-ID: <tip-288f023e708efd89d77ce9acf977a33a623ae83d@git.kernel.org>
Date:	Sat, 19 Sep 2009 17:01:20 GMT
From:	tip-bot for Arjan van de Ven <arjan@...radead.org>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, paulus@...ba.org, hpa@...or.com,
	mingo@...hat.com, arjan@...ux.intel.com, arjan@...radead.org,
	tglx@...utronix.de, mingo@...e.hu, len.brown@...el.com
Subject: [tip:perfcounters/core] tracing, x86, cpuidle: Move the end point of a C state in the power tracer

Commit-ID:  288f023e708efd89d77ce9acf977a33a623ae83d
Gitweb:     http://git.kernel.org/tip/288f023e708efd89d77ce9acf977a33a623ae83d
Author:     Arjan van de Ven <arjan@...radead.org>
AuthorDate: Sat, 19 Sep 2009 13:35:33 +0200
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Sat, 19 Sep 2009 18:57:52 +0200

tracing, x86, cpuidle: Move the end point of a C state in the power tracer

The "end of a C state" trace point currently happens before
the code runs that corrects the TSC for having stopped during idle.

The result of this is that the timestamp of the end-of-C-state event
is garbage on cpus where the TSC stops during idle.

This patch moves the end point of the C state to after the timekeeping
engine of the kernel has been corrected.

Signed-off-by: Arjan van de Ven <arjan@...ux.intel.com>
Cc: Len Brown <len.brown@...el.com>
Cc: fweisbec@...il.com
Cc: peterz@...radead.org
Cc: Paul Mackerras <paulus@...ba.org>
LKML-Reference: <20090919133533.139c2a46@...radead.org>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 arch/x86/kernel/process.c |    3 ---
 drivers/cpuidle/cpuidle.c |    2 ++
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 7b60e39..847ab41 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -309,7 +309,6 @@ void default_idle(void)
 		else
 			local_irq_enable();
 		current_thread_info()->status |= TS_POLLING;
-		trace_power_end(0);
 	} else {
 		local_irq_enable();
 		/* loop is done by the caller */
@@ -377,7 +376,6 @@ void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
 		if (!need_resched())
 			__mwait(ax, cx);
 	}
-	trace_power_end(0);
 }
 
 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
@@ -394,7 +392,6 @@ static void mwait_idle(void)
 			__sti_mwait(0, 0);
 		else
 			local_irq_enable();
-		trace_power_end(0);
 	} else
 		local_irq_enable();
 }
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 8504a21..ad41f19 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -17,6 +17,7 @@
 #include <linux/cpuidle.h>
 #include <linux/ktime.h>
 #include <linux/hrtimer.h>
+#include <trace/events/power.h>
 
 #include "cpuidle.h"
 
@@ -91,6 +92,7 @@ static void cpuidle_idle_call(void)
 	/* give the governor an opportunity to reflect on the outcome */
 	if (cpuidle_curr_governor->reflect)
 		cpuidle_curr_governor->reflect(dev);
+	trace_power_end(0);
 }
 
 /**
--
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