[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>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/x86_64/kernel/pmtimer.c b/arch/x86_64/kernel/pmtimer.c
index 5c51d10408a6..ee5ee4891f3d 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);
 }