Commit b8a83fcb authored by Pavel Tatashin's avatar Pavel Tatashin Committed by David S. Miller
Browse files

sparc64: access tick function from variable 



In timer_64.c tick functions are access via pointer (tick_ops), every time
clock is read, there is one extra load to get to the function.

This patch optimizes it, by accessing functions pointer from value.

Current ched_clock():
sethi  %hi(0xb9b400), %g1
ldx  [ %g1 + 0x250 ], %g1  ! <tick_ops>
ldx  [ %g1 ], %g1
call  %g1
nop
sethi  %hi(0xb9b400), %g1
ldx  [ %g1 + 0x300 ], %g1  ! <timer_ticks_per_nsec_quotient>
mulx  %o0, %g1, %g1
rett  %i7 + 8
srlx  %g1, 0xa, %o0

New sched_clock():
sethi  %hi(0xb9b400), %g1
ldx  [ %g1 + 0x340 ], %g1
call  %g1
nop
sethi  %hi(0xb9b400), %g1
ldx  [ %g1 + 0x378 ], %g1
mulx  %o0, %g1, %g1
rett  %i7 + 8
srlx  %g1, 0xa, %o0

Before three loads, now two loads.

Signed-off-by: default avatarPavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: default avatarShannon Nelson <shannon.nelson@oracle.com>
Reviewed-by: default avatarSteven Sistare <steven.sistare@oracle.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 68a79217

arch/sparc/kernel/time_64.c

+16 −14
Original line number Diff line number Diff line
@@ -585,6 +585,7 @@ fs_initcall(clock_init); 
/* This is gets the master TICK_INT timer going. */

static unsigned long sparc64_init_timers(void)

{

	struct sparc64_tick_ops *ops = NULL;

	struct device_node *dp;

	unsigned long freq;
@@ -598,16 +599,17 @@ static unsigned long sparc64_init_timers(void) 
		impl = ((ver >> 32) & 0xffff);

		if (manuf == 0x17 && impl == 0x13) {

			/* Hummingbird, aka Ultra-IIe */

			tick_ops = &hbtick_operations;

			ops = &hbtick_operations;

			freq = of_getintprop_default(dp, "stick-frequency", 0);

		} else {

			tick_ops = &tick_operations;

			freq = local_cpu_data().clock_tick;

		}

	} else {

		tick_ops = &stick_operations;

		ops = &stick_operations;

		freq = of_getintprop_default(dp, "stick-frequency", 0);

	}

	if (ops)

		memcpy(&tick_operations, ops, sizeof(struct sparc64_tick_ops));



	return freq;

}
@@ -671,12 +673,12 @@ core_initcall(register_sparc64_cpufreq_notifier); 
static int sparc64_next_event(unsigned long delta,

			      struct clock_event_device *evt)

{

	return tick_ops->add_compare(delta) ? -ETIME : 0;

	return tick_operations.add_compare(delta) ? -ETIME : 0;

}



static int sparc64_timer_shutdown(struct clock_event_device *evt)

{

	tick_ops->disable_irq();

	tick_operations.disable_irq();

	return 0;

}
@@ -693,7 +695,7 @@ static DEFINE_PER_CPU(struct clock_event_device, sparc64_events); 
void __irq_entry timer_interrupt(int irq, struct pt_regs *regs)

{

	struct pt_regs *old_regs = set_irq_regs(regs);

	unsigned long tick_mask = tick_ops->softint_mask;

	unsigned long tick_mask = tick_operations.softint_mask;

	int cpu = smp_processor_id();

	struct clock_event_device *evt = &per_cpu(sparc64_events, cpu);
@@ -728,7 +730,7 @@ void setup_sparc64_timer(void) 
			     : "=r" (pstate)

			     : "i" (PSTATE_IE));



	tick_ops->init_tick();

	tick_operations.init_tick();



	/* Restore PSTATE_IE. */

	__asm__ __volatile__("wrpr	%0, 0x0, %%pstate"
@@ -757,9 +759,9 @@ void __delay(unsigned long loops) 
{

	unsigned long bclock, now;



	bclock = tick_ops->get_tick();

	bclock = tick_operations.get_tick();

	do {

		now = tick_ops->get_tick();

		now = tick_operations.get_tick();

	} while ((now-bclock) < loops);

}

EXPORT_SYMBOL(__delay);
@@ -772,7 +774,7 @@ EXPORT_SYMBOL(udelay); 


static u64 clocksource_tick_read(struct clocksource *cs)

{

	return tick_ops->get_tick();

	return tick_operations.get_tick();

}



void __init time_init(void)
@@ -784,14 +786,14 @@ void __init time_init(void) 
	timer_ticks_per_nsec_quotient =

		clocksource_hz2mult(freq, SPARC64_NSEC_PER_CYC_SHIFT);



	clocksource_tick.name = tick_ops->name;

	clocksource_tick.name = tick_operations.name;

	clocksource_tick.read = clocksource_tick_read;



	clocksource_register_hz(&clocksource_tick, freq);

	printk("clocksource: mult[%x] shift[%d]\n",

	       clocksource_tick.mult, clocksource_tick.shift);



	sparc64_clockevent.name = tick_ops->name;

	sparc64_clockevent.name = tick_operations.name;

	clockevents_calc_mult_shift(&sparc64_clockevent, freq, 4);



	sparc64_clockevent.max_delta_ns =
@@ -809,7 +811,7 @@ void __init time_init(void) 


unsigned long long sched_clock(void)

{

	unsigned long ticks = tick_ops->get_tick();

	unsigned long ticks = tick_operations.get_tick();



	return (ticks * timer_ticks_per_nsec_quotient)

		>> SPARC64_NSEC_PER_CYC_SHIFT;
@@ -817,6 +819,6 @@ unsigned long long sched_clock(void) 


int read_current_timer(unsigned long *timer_val)

{

	*timer_val = tick_ops->get_tick();

	*timer_val = tick_operations.get_tick();

	return 0;

}

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