From 5ee613b6751cd91db4b6bd7c1dc9d2f9cf65cde2 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Wed, 30 Jan 2008 13:30:06 +0100
Subject: [PATCH] x86: idle wakeup event in the HLT loop

do a proper idle-wakeup event on HLT as well - some CPUs stop the TSC
in HLT too, not just when going through the ACPI methods.

(the ACPI idle code already does this.)

[ update the 64-bit side too, as noticed by Jiri Slaby. ]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/process_32.c | 15 ++++++++++++---
 arch/x86/kernel/process_64.c | 13 ++++++++++---
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 46d391d49de8..a63d2d2556ee 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -113,10 +113,19 @@ void default_idle(void)
 		smp_mb();
 
 		local_irq_disable();
-		if (!need_resched())
+		if (!need_resched()) {
+			ktime_t t0, t1;
+			u64 t0n, t1n;
+
+			t0 = ktime_get();
+			t0n = ktime_to_ns(t0);
 			safe_halt();	/* enables interrupts racelessly */
-		else
-			local_irq_enable();
+			local_irq_disable();
+			t1 = ktime_get();
+			t1n = ktime_to_ns(t1);
+			sched_clock_idle_wakeup_event(t1n - t0n);
+		}
+		local_irq_enable();
 		current_thread_info()->status |= TS_POLLING;
 	} else {
 		/* loop is done by the caller */
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index c2db7ef93565..40fed477f3e5 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -116,9 +116,16 @@ static void default_idle(void)
 	smp_mb();
 	local_irq_disable();
 	if (!need_resched()) {
-		/* Enables interrupts one instruction before HLT.
-		   x86 special cases this so there is no race. */
-		safe_halt();
+		ktime_t t0, t1;
+		u64 t0n, t1n;
+
+		t0 = ktime_get();
+		t0n = ktime_to_ns(t0);
+		safe_halt();	/* enables interrupts racelessly */
+		local_irq_disable();
+		t1 = ktime_get();
+		t1n = ktime_to_ns(t1);
+		sched_clock_idle_wakeup_event(t1n - t0n);
 	} else
 		local_irq_enable();
 	current_thread_info()->status |= TS_POLLING;
-- 
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