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Commit eae3fc98 authored by Pavel Tatashin's avatar Pavel Tatashin Committed by David S. Miller
Browse files

sparc64: optimize functions that access tick 



Replace read tick function pointers with the new hot-patched get_tick().
This optimizes the performance of functions such as: sched_clock()

Signed-off-by: default avatarPavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: default avatarSteven Sistare <steven.sistare@oracle.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4929c83a

arch/sparc/kernel/time_64.c

+13 −9
Original line number Original line Diff line number Diff line
@@ -752,12 +752,10 @@ static unsigned long tb_ticks_per_usec __read_mostly; 




void __delay(unsigned long loops)

void __delay(unsigned long loops)

{

{

	unsigned long bclock, now;

	unsigned long bclock = get_tick();





	bclock = tick_operations.get_tick();

	while ((get_tick() - bclock) < loops)

	do {

		;

		now = tick_operations.get_tick();

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

}

}

EXPORT_SYMBOL(__delay);

EXPORT_SYMBOL(__delay);
@@ -769,7 +767,7 @@ EXPORT_SYMBOL(udelay); 




static u64 clocksource_tick_read(struct clocksource *cs)

static u64 clocksource_tick_read(struct clocksource *cs)

{

{

	return tick_operations.get_tick();

	return get_tick();

}

}





static void __init get_tick_patch(void)

static void __init get_tick_patch(void)
@@ -853,13 +851,19 @@ unsigned long long sched_clock(void) 
{

{

	unsigned long quotient = tick_operations.ticks_per_nsec_quotient;

	unsigned long quotient = tick_operations.ticks_per_nsec_quotient;

	unsigned long offset = tick_operations.offset;

	unsigned long offset = tick_operations.offset;

	unsigned long ticks = tick_operations.get_tick();





	return ((ticks * quotient) >> SPARC64_NSEC_PER_CYC_SHIFT) - offset;

	/* Use barrier so the compiler emits the loads first and overlaps load

	 * latency with reading tick, because reading %tick/%stick is a

	 * post-sync instruction that will flush and restart subsequent

	 * instructions after it commits.

	 */

	barrier();



	return ((get_tick() * quotient) >> SPARC64_NSEC_PER_CYC_SHIFT) - offset;

}

}





int read_current_timer(unsigned long *timer_val)

int read_current_timer(unsigned long *timer_val)

{

{

	*timer_val = tick_operations.get_tick();

	*timer_val = get_tick();

	return 0;

	return 0;

}
 
}