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Commit 288f023e authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Ingo Molnar
Browse files

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: default avatarArjan van de Ven <arjan@linux.intel.com>
Cc: Len Brown <len.brown@intel.com>
Cc: fweisbec@gmail.com
Cc: peterz@infradead.org
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20090919133533.139c2a46@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 964a0b3d

arch/x86/kernel/process.c

+0 −3
Original line number Diff line number Diff line
@@ -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();

}

drivers/cpuidle/cpuidle.c

+2 −0
Original line number Diff line number Diff line
@@ -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);

}



/**