[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, 7 insertions, 2 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index f06d059edef5..7d1027a4dd21 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -818,6 +818,11 @@ static void deactivate_task(struct task_struct *p, runqueue_t *rq)
  * the target CPU.
  */
 #ifdef CONFIG_SMP
+
+#ifndef tsk_is_polling
+#define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
+#endif
+
 static void resched_task(task_t *p)
 {
         int cpu;
@@ -833,9 +838,9 @@ static void resched_task(task_t *p)
         if (cpu == smp_processor_id())
                 return;
 
-        /* NEED_RESCHED must be visible before we test POLLING_NRFLAG */
+        /* NEED_RESCHED must be visible before we test polling */
         smp_mb();
-        if (!test_tsk_thread_flag(p, TIF_POLLING_NRFLAG))
+        if (!tsk_is_polling(p))
                 smp_send_reschedule(cpu);
 }
 #else