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Commit 6e6b44e8 authored by Milton Miller's avatar Milton Miller Committed by Paul Mackerras
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[POWERPC] Timer interrupt: use a struct for two per_cpu varables 



timer_interrupt() was calculating per_cpu_offset several times, having to
start from the toc because of potential aliasing issues.

Placing both decrementer per_cpu varables in a struct and calculating
the address once with __get_cpu_var results in better code on both 32
and 64 bit.

Signed-off-by: default avatarMilton Miller <miltonm@bga.com>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 8b5621f1

arch/powerpc/kernel/time.c

+12 −8
Original line number Diff line number Diff line
@@ -116,8 +116,12 @@ static struct clock_event_device decrementer_clockevent = { 
       .features       = CLOCK_EVT_FEAT_ONESHOT,

};



static DEFINE_PER_CPU(struct clock_event_device, decrementers);

static DEFINE_PER_CPU(u64, decrementer_next_tb);

struct decrementer_clock {

	struct clock_event_device event;

	u64 next_tb;

};



static DEFINE_PER_CPU(struct decrementer_clock, decrementers);



#ifdef CONFIG_PPC_ISERIES

static unsigned long __initdata iSeries_recal_titan;
@@ -555,8 +559,8 @@ void __init iSeries_time_init_early(void) 
void timer_interrupt(struct pt_regs * regs)

{

	struct pt_regs *old_regs;

	int cpu = smp_processor_id();

	struct clock_event_device *evt = &per_cpu(decrementers, cpu);

	struct decrementer_clock *decrementer =  &__get_cpu_var(decrementers);

	struct clock_event_device *evt = &decrementer->event;

	u64 now;



	/* Ensure a positive value is written to the decrementer, or else
@@ -569,9 +573,9 @@ void timer_interrupt(struct pt_regs * regs) 
#endif



	now = get_tb_or_rtc();

	if (now < per_cpu(decrementer_next_tb, cpu)) {

	if (now < decrementer->next_tb) {

		/* not time for this event yet */

		now = per_cpu(decrementer_next_tb, cpu) - now;

		now = decrementer->next_tb - now;

		if (now <= DECREMENTER_MAX)

			set_dec((int)now);

		return;
@@ -810,7 +814,7 @@ void __init clocksource_init(void) 
static int decrementer_set_next_event(unsigned long evt,

				      struct clock_event_device *dev)

{

	__get_cpu_var(decrementer_next_tb) = get_tb_or_rtc() + evt;

	__get_cpu_var(decrementers).next_tb = get_tb_or_rtc() + evt;

	set_dec(evt);

	return 0;

}
@@ -824,7 +828,7 @@ static void decrementer_set_mode(enum clock_event_mode mode, 


static void register_decrementer_clockevent(int cpu)

{

	struct clock_event_device *dec = &per_cpu(decrementers, cpu);

	struct clock_event_device *dec = &per_cpu(decrementers, cpu).event;



	*dec = decrementer_clockevent;

	dec->cpumask = cpumask_of_cpu(cpu);