[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>

4 files changed, 11 insertions, 12 deletions

diff --git a/arch/i386/kernel/apm.c b/arch/i386/kernel/apm.c
index 9e819eb68229..7c5729d1fd06 100644
--- a/arch/i386/kernel/apm.c
+++ b/arch/i386/kernel/apm.c
@@ -764,9 +764,9 @@ static int apm_do_idle(void)
 	int	idled = 0;
 	int	polling;
 
-	polling = test_thread_flag(TIF_POLLING_NRFLAG);
+	polling = !!(current_thread_info()->status & TS_POLLING);
 	if (polling) {
-		clear_thread_flag(TIF_POLLING_NRFLAG);
+		current_thread_info()->status &= ~TS_POLLING;
 		smp_mb__after_clear_bit();
 	}
 	if (!need_resched()) {
@@ -774,7 +774,7 @@ static int apm_do_idle(void)
 		ret = apm_bios_call_simple(APM_FUNC_IDLE, 0, 0, &eax);
 	}
 	if (polling)
-		set_thread_flag(TIF_POLLING_NRFLAG);
+		current_thread_info()->status |= TS_POLLING;
 
 	if (!idled)
 		return 0;
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index 525432e3fef7..6946b06e2784 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -102,7 +102,7 @@ void default_idle(void)
 	local_irq_enable();
 
 	if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
-		clear_thread_flag(TIF_POLLING_NRFLAG);
+		current_thread_info()->status &= ~TS_POLLING;
 		smp_mb__after_clear_bit();
 		while (!need_resched()) {
 			local_irq_disable();
@@ -111,7 +111,7 @@ void default_idle(void)
 			else
 				local_irq_enable();
 		}
-		set_thread_flag(TIF_POLLING_NRFLAG);
+		current_thread_info()->status |= TS_POLLING;
 	} else {
 		while (!need_resched())
 			cpu_relax();
@@ -174,7 +174,7 @@ void cpu_idle(void)
 {
 	int cpu = smp_processor_id();
 
-	set_thread_flag(TIF_POLLING_NRFLAG);
+	current_thread_info()->status |= TS_POLLING;
 
 	/* endless idle loop with no priority at all */
 	while (1) {
diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index 355d57970ba3..b045c279136c 100644
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -272,9 +272,9 @@ cpu_idle (void)
 	/* endless idle loop with no priority at all */
 	while (1) {
 		if (can_do_pal_halt)
-			clear_thread_flag(TIF_POLLING_NRFLAG);
+			current_thread_info()->status &= ~TS_POLLING;
 		else
-			set_thread_flag(TIF_POLLING_NRFLAG);
+			current_thread_info()->status |= TS_POLLING;
 
 		if (!need_resched()) {
 			void (*idle)(void);
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()) {