[PATCH] i386/x86-64/ia64: Move polling flag into thread_info_status

During some profiling I noticed that default_idle causes a lot of
memory traffic. I think that is caused by the atomic operations
to clear/set the polling flag in thread_info. There is actually
no reason to make this atomic - only the idle thread does it
to itself, other CPUs only read it. So I moved it into ti->status.

Converted i386/x86-64/ia64 for now because that was the easiest
way to fix ACPI which also manipulates these flags in its idle
function.

Cc: Nick Piggin <npiggin@novell.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
index d6fa41459c80..b596837a1527 100644
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -110,7 +110,7 @@ static void default_idle(void)
 {
         local_irq_enable();
 
-        clear_thread_flag(TIF_POLLING_NRFLAG);
+        current_thread_info()->status &= ~TS_POLLING;
         smp_mb__after_clear_bit();
         while (!need_resched()) {
                 local_irq_disable();
@@ -119,7 +119,7 @@ static void default_idle(void)
                 else
                         local_irq_enable();
         }
-        set_thread_flag(TIF_POLLING_NRFLAG);
+        current_thread_info()->status |= TS_POLLING;
 }
 
 /*
@@ -202,8 +202,7 @@ static inline void play_dead(void)
  */
 void cpu_idle (void)
 {
-        set_thread_flag(TIF_POLLING_NRFLAG);
-
+        current_thread_info()->status |= TS_POLLING;
         /* endless idle loop with no priority at all */
         while (1) {
                 while (!need_resched()) {