From: Andi Kleen <ak@suse.de>
Date: Sat, 25 Mar 2006 15:32:04 +0000 (+0100)
Subject: [PATCH] x86_64: Add cpu_relax() to busy loops in PM timer code
X-Git-Tag: v3.12-rc1~37490
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c36cd16f78a5dd740a619ef8445e35a73484d58b;p=kernel%2Fkernel-generic.git

[PATCH] x86_64: Add cpu_relax() to busy loops in PM timer code

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/arch/x86_64/kernel/pmtimer.c b/arch/x86_64/kernel/pmtimer.c
index 5c51d10..ee5ee48 100644
--- a/arch/x86_64/kernel/pmtimer.c
+++ b/arch/x86_64/kernel/pmtimer.c
@@ -86,7 +86,7 @@ static unsigned pmtimer_wait_tick(void)
 	for (a = b = inl(pmtmr_ioport) & ACPI_PM_MASK;
 	     a == b;
 	     b = inl(pmtmr_ioport) & ACPI_PM_MASK)
-		;
+		cpu_relax();
 	return b;
 }
 
@@ -97,6 +97,7 @@ void pmtimer_wait(unsigned us)
 	a = pmtimer_wait_tick();
 	do {
 		b = inl(pmtmr_ioport);
+		cpu_relax();
 	} while (cyc2us(b - a) < us);
 }