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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: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Pavel Tatashin 2017-06-12 16:41:42 -04:00 committed by David S. Miller
parent 68a792174d
commit b8a83fcb78
1 changed files with 16 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
arch/sparc/kernel/time_64.c
View File

@ -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;
}