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Commit 495ab9c0 authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
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[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: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent d9005b52

arch/i386/kernel/apm.c

+3 −3
Original line number Diff line number Diff line
@@ -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;

arch/i386/kernel/process.c

+3 −3
Original line number Diff line number Diff line
@@ -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) {

arch/ia64/kernel/process.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

arch/x86_64/kernel/process.c

+3 −4
Original line number Diff line number Diff line
@@ -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()) {

drivers/acpi/processor_idle.c

+6 −6
Original line number Diff line number Diff line
@@ -206,11 +206,11 @@ acpi_processor_power_activate(struct acpi_processor *pr, 


static void acpi_safe_halt(void)

{

	clear_thread_flag(TIF_POLLING_NRFLAG);

	current_thread_info()->status &= ~TS_POLLING;

	smp_mb__after_clear_bit();

	if (!need_resched())

		safe_halt();

	set_thread_flag(TIF_POLLING_NRFLAG);

	current_thread_info()->status |= TS_POLLING;

}



static atomic_t c3_cpu_count;
@@ -330,10 +330,10 @@ static void acpi_processor_idle(void) 
	 * Invoke the current Cx state to put the processor to sleep.

	 */

	if (cx->type == ACPI_STATE_C2 || cx->type == ACPI_STATE_C3) {

		clear_thread_flag(TIF_POLLING_NRFLAG);

		current_thread_info()->status &= ~TS_POLLING;

		smp_mb__after_clear_bit();

		if (need_resched()) {

			set_thread_flag(TIF_POLLING_NRFLAG);

			current_thread_info()->status |= TS_POLLING;

			local_irq_enable();

			return;

		}
@@ -371,7 +371,7 @@ static void acpi_processor_idle(void) 
		t2 = inl(acpi_fadt.xpm_tmr_blk.address);

		/* Re-enable interrupts */

		local_irq_enable();

		set_thread_flag(TIF_POLLING_NRFLAG);

		current_thread_info()->status |= TS_POLLING;

		/* Compute time (ticks) that we were actually asleep */

		sleep_ticks =

		    ticks_elapsed(t1, t2) - cx->latency_ticks - C2_OVERHEAD;
@@ -411,7 +411,7 @@ static void acpi_processor_idle(void) 


		/* Re-enable interrupts */

		local_irq_enable();

		set_thread_flag(TIF_POLLING_NRFLAG);

		current_thread_info()->status |= TS_POLLING;

		/* Compute time (ticks) that we were actually asleep */

		sleep_ticks =

		    ticks_elapsed(t1, t2) - cx->latency_ticks - C3_OVERHEAD;