mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

[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: Milton Miller <miltonm@bga.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Milton Miller 2007-12-14 15:52:15 +11:00 committed by Paul Mackerras
parent 8b5621f183
commit 6e6b44e822
1 changed files with 12 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
arch/powerpc/kernel/time.c
View File

@ -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);