fs: use kmem_cache_zalloc instead
[pv_ops_mirror.git] / include / asm-x86 / timer.h
blob0db7e994fb8b4f40ad9a96ecf2258d7fd6dc57f6
1 #ifndef _ASMi386_TIMER_H
2 #define _ASMi386_TIMER_H
3 #include <linux/init.h>
4 #include <linux/pm.h>
6 #define TICK_SIZE (tick_nsec / 1000)
8 unsigned long long native_sched_clock(void);
9 unsigned long native_calculate_cpu_khz(void);
11 extern int timer_ack;
12 extern int no_timer_check;
13 extern int recalibrate_cpu_khz(void);
15 #ifndef CONFIG_PARAVIRT
16 #define calculate_cpu_khz() native_calculate_cpu_khz()
17 #endif
19 /* Accellerators for sched_clock()
20 * convert from cycles(64bits) => nanoseconds (64bits)
21 * basic equation:
22 * ns = cycles / (freq / ns_per_sec)
23 * ns = cycles * (ns_per_sec / freq)
24 * ns = cycles * (10^9 / (cpu_khz * 10^3))
25 * ns = cycles * (10^6 / cpu_khz)
27 * Then we use scaling math (suggested by george@mvista.com) to get:
28 * ns = cycles * (10^6 * SC / cpu_khz) / SC
29 * ns = cycles * cyc2ns_scale / SC
31 * And since SC is a constant power of two, we can convert the div
32 * into a shift.
34 * We can use khz divisor instead of mhz to keep a better percision, since
35 * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
36 * (mathieu.desnoyers@polymtl.ca)
38 * -johnstul@us.ibm.com "math is hard, lets go shopping!"
40 extern unsigned long cyc2ns_scale __read_mostly;
42 #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
44 static inline unsigned long long cycles_2_ns(unsigned long long cyc)
46 return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
50 #endif