linux/include/asm-i386/timex.h
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00

53 lines
1.2 KiB
C

/*
* linux/include/asm-i386/timex.h
*
* i386 architecture timex specifications
*/
#ifndef _ASMi386_TIMEX_H
#define _ASMi386_TIMEX_H
#include <linux/config.h>
#include <asm/processor.h>
#ifdef CONFIG_X86_ELAN
# define CLOCK_TICK_RATE 1189200 /* AMD Elan has different frequency! */
#else
# define CLOCK_TICK_RATE 1193182 /* Underlying HZ */
#endif
/*
* Standard way to access the cycle counter on i586+ CPUs.
* Currently only used on SMP.
*
* If you really have a SMP machine with i486 chips or older,
* compile for that, and this will just always return zero.
* That's ok, it just means that the nicer scheduling heuristics
* won't work for you.
*
* We only use the low 32 bits, and we'd simply better make sure
* that we reschedule before that wraps. Scheduling at least every
* four billion cycles just basically sounds like a good idea,
* regardless of how fast the machine is.
*/
typedef unsigned long long cycles_t;
static inline cycles_t get_cycles (void)
{
unsigned long long ret=0;
#ifndef CONFIG_X86_TSC
if (!cpu_has_tsc)
return 0;
#endif
#if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC)
rdtscll(ret);
#endif
return ret;
}
extern unsigned long cpu_khz;
#endif