2 * linux/include/asm-i386/timex.h
4 * i386 architecture timex specifications
6 #ifndef _ASMi386_TIMEX_H
7 #define _ASMi386_TIMEX_H
9 #include <asm/processor.h>
11 #ifdef CONFIG_X86_ELAN
12 # define CLOCK_TICK_RATE 1189200 /* AMD Elan has different frequency! */
14 # define CLOCK_TICK_RATE 1193182 /* Underlying HZ */
19 * Standard way to access the cycle counter on i586+ CPUs.
20 * Currently only used on SMP.
22 * If you really have a SMP machine with i486 chips or older,
23 * compile for that, and this will just always return zero.
24 * That's ok, it just means that the nicer scheduling heuristics
27 * We only use the low 32 bits, and we'd simply better make sure
28 * that we reschedule before that wraps. Scheduling at least every
29 * four billion cycles just basically sounds like a good idea,
30 * regardless of how fast the machine is.
32 typedef unsigned long long cycles_t;
34 static inline cycles_t get_cycles (void)
36 unsigned long long ret=0;
38 #ifndef CONFIG_X86_TSC
43 #if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC)
49 extern unsigned int cpu_khz;
51 extern int read_current_timer(unsigned long *timer_value);
52 #define ARCH_HAS_READ_CURRENT_TIMER 1