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Subject[PATCH] trace: Move the end point of a C state in the power tracer
From c1ffb79a8e87501ccaf269517566f438220f1c49 Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <arjan@linux.intel.com>
Date: Sat, 19 Sep 2009 13:09:16 +0200
Subject: [PATCH] trace: 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@linux.intel.com>
---
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 98e9cac..230d054 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -299,7 +299,6 @@ 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 */
@@ -367,7 +366,6 @@ 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 */
@@ -384,7 +382,6 @@ 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);
}

/**
--
1.6.0.6



--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org


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