2 * linux/include/asm-i386/timex.h
4 * i386 architecture timex specifications
6 #ifndef _ASMi386_TIMEX_H
7 #define _ASMi386_TIMEX_H
9 #include <linux/config.h>
12 #ifdef CONFIG_X86_ELAN
13 # define CLOCK_TICK_RATE 1189200 /* AMD Elan has different frequency! */
15 # define CLOCK_TICK_RATE 1193182 /* Underlying HZ */
18 #define CLOCK_TICK_FACTOR 20 /* Factor of both 1000000 and CLOCK_TICK_RATE */
19 #define FINETUNE ((((((long)LATCH * HZ - CLOCK_TICK_RATE) << SHIFT_HZ) * \
20 (1000000/CLOCK_TICK_FACTOR) / (CLOCK_TICK_RATE/CLOCK_TICK_FACTOR)) \
21 << (SHIFT_SCALE-SHIFT_HZ)) / HZ)
24 * Standard way to access the cycle counter on i586+ CPUs.
25 * Currently only used on SMP.
27 * If you really have a SMP machine with i486 chips or older,
28 * compile for that, and this will just always return zero.
29 * That's ok, it just means that the nicer scheduling heuristics
32 * We only use the low 32 bits, and we'd simply better make sure
33 * that we reschedule before that wraps. Scheduling at least every
34 * four billion cycles just basically sounds like a good idea,
35 * regardless of how fast the machine is.
37 typedef unsigned long long cycles_t;
39 extern cycles_t cacheflush_time;
41 static inline cycles_t get_cycles (void)
43 #ifndef CONFIG_X86_TSC
46 unsigned long long ret;
53 extern unsigned long cpu_khz;