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x86: provide delay loop for x86_64.

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This is for consistency with i386. We call use_tsc_delay()
at tsc initialization for x86_64, so we'll be always using it.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Glauber Costa 2008-06-24 09:34:08 -03:00 committed by Ingo Molnar
parent ff1b15b646
commit 0a4d8a472f
2 changed files with 41 additions and 4 deletions
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1
arch/x86/kernel/tsc.c
View File

@ -513,6 +513,7 @@ void __init tsc_init(void)
*/ */
for_each_possible_cpu(cpu) for_each_possible_cpu(cpu)
set_cyc2ns_scale(cpu_khz, cpu); set_cyc2ns_scale(cpu_khz, cpu);
use_tsc_delay();
if (tsc_disabled > 0) if (tsc_disabled > 0)
return; return;

44
arch/x86/lib/delay_64.c
View File

@ -22,13 +22,28 @@
#include <asm/smp.h> #include <asm/smp.h>
#endif #endif
int __devinit read_current_timer(unsigned long *timer_value) /* simple loop based delay: */
static void delay_loop(unsigned long loops)
{ {
rdtscll(*timer_value); asm volatile(
return 0; " test %0,%0 \n"
" jz 3f \n"
" jmp 1f \n"
".align 16 \n"
"1: jmp 2f \n"
".align 16 \n"
"2: dec %0 \n"
" jnz 2b \n"
"3: dec %0 \n"
: /* we don't need output */
:"a" (loops)
);
} }
void __delay(unsigned long loops) static void delay_tsc(unsigned long loops)
{ {
unsigned bclock, now; unsigned bclock, now;
int cpu; int cpu;
@ -63,6 +78,27 @@ void __delay(unsigned long loops)
} }
preempt_enable(); preempt_enable();
} }
static void (*delay_fn)(unsigned long) = delay_loop;
void use_tsc_delay(void)
{
delay_fn = delay_tsc;
}
int __devinit read_current_timer(unsigned long *timer_value)
{
if (delay_fn == delay_tsc) {
rdtscll(*timer_value);
return 0;
}
return -1;
}
void __delay(unsigned long loops)
{
delay_fn(loops);
}
EXPORT_SYMBOL(__delay); EXPORT_SYMBOL(__delay);
inline void __const_udelay(unsigned long xloops) inline void __const_udelay(unsigned long xloops)