linux-stable/include/asm-x86_64/timex.h
Andi Kleen c818a18146 [PATCH] x86_64: On Intel CPUs don't do an additional CPU sync before RDTSC
RDTSC serialization using cpuid is not needed for Intel platforms.
This increases gettimeofday performance.

Cc: vojtech@suse.cz
Cc: rohit.seth@intel.com

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-11 19:04:58 -08:00

49 lines
1.1 KiB
C

/*
* linux/include/asm-x86_64/timex.h
*
* x86-64 architecture timex specifications
*/
#ifndef _ASMx8664_TIMEX_H
#define _ASMx8664_TIMEX_H
#include <asm/8253pit.h>
#include <asm/msr.h>
#include <asm/vsyscall.h>
#include <asm/hpet.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <linux/compiler.h>
#define CLOCK_TICK_RATE PIT_TICK_RATE /* Underlying HZ */
typedef unsigned long long cycles_t;
static inline cycles_t get_cycles (void)
{
unsigned long long ret;
rdtscll(ret);
return ret;
}
/* Like get_cycles, but make sure the CPU is synchronized. */
static __always_inline cycles_t get_cycles_sync(void)
{
unsigned long long ret;
unsigned eax;
/* Don't do an additional sync on CPUs where we know
RDTSC is already synchronous. */
alternative_io(ASM_NOP2, "cpuid", X86_FEATURE_SYNC_RDTSC,
"=a" (eax), "0" (1) : "ebx","ecx","edx","memory");
rdtscll(ret);
return ret;
}
extern unsigned int cpu_khz;
extern int read_current_timer(unsigned long *timer_value);
#define ARCH_HAS_READ_CURRENT_TIMER 1
extern struct vxtime_data vxtime;
#endif