projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1965aae3 PA |
1 | #ifndef _ASM_X86_TIMER_H |
| 2 | #define _ASM_X86_TIMER_H | |
| 1da177e4 | 3 | #include <linux/init.h> |
| c3c433e4 | 4 | #include <linux/pm.h> |
| 53d517cd | 5 | #include <linux/percpu.h> |
| 1da177e4 | 6 | |
| 1da177e4 | 7 | #define TICK_SIZE (tick_nsec / 1000) |
| 6cb9a835 | 8 | |
| 6cb9a835 | 9 | unsigned long long native_sched_clock(void); |
| e93ef949 | 10 | unsigned long native_calibrate_tsc(void); |
| 6cb9a835 | 11 | |
| cc038491 | 12 | #ifdef CONFIG_X86_32 |
| 1da177e4 | 13 | extern int timer_ack; |
| c5d28fb2 | 14 | extern int recalibrate_cpu_khz(void); |
| cc038491 JS |
15 | #endif /* CONFIG_X86_32 */ |
| 16 | ||
| 17 | extern int no_timer_check; | |
| 1da177e4 | 18 | |
| 6cb9a835 | 19 | #ifndef CONFIG_PARAVIRT |
| e93ef949 | 20 | #define calibrate_tsc() native_calibrate_tsc() |
| 6cb9a835 ZA |
21 | #endif |
| 22 | ||
| 53d517cd | 23 | /* Accelerators for sched_clock() |
| 688340ea JF |
24 | * convert from cycles(64bits) => nanoseconds (64bits) |
| 25 | * basic equation: | |
| 26 | * ns = cycles / (freq / ns_per_sec) | |
| 27 | * ns = cycles * (ns_per_sec / freq) | |
| 28 | * ns = cycles * (10^9 / (cpu_khz * 10^3)) | |
| 29 | * ns = cycles * (10^6 / cpu_khz) | |
| 30 | * | |
| 31 | * Then we use scaling math (suggested by george@mvista.com) to get: | |
| 32 | * ns = cycles * (10^6 * SC / cpu_khz) / SC | |
| 33 | * ns = cycles * cyc2ns_scale / SC | |
| 34 | * | |
| 35 | * And since SC is a constant power of two, we can convert the div | |
| 36 | * into a shift. | |
| 37 | * | |
| 53d517cd | 38 | * We can use khz divisor instead of mhz to keep a better precision, since |
| 688340ea JF |
39 | * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. |
| 40 | * (mathieu.desnoyers@polymtl.ca) | |
| 41 | * | |
| 42 | * -johnstul@us.ibm.com "math is hard, lets go shopping!" | |
| 43 | */ | |
| 53d517cd GC |
44 | |
| 45 | DECLARE_PER_CPU(unsigned long, cyc2ns); | |
| 688340ea JF |
46 | |
| 47 | #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */ | |
| 48 | ||
| 53d517cd | 49 | static inline unsigned long long __cycles_2_ns(unsigned long long cyc) |
| 688340ea | 50 | { |
| 53d517cd | 51 | return cyc * per_cpu(cyc2ns, smp_processor_id()) >> CYC2NS_SCALE_FACTOR; |
| 688340ea JF |
52 | } |
| 53 | ||
| 53d517cd GC |
54 | static inline unsigned long long cycles_2_ns(unsigned long long cyc) |
| 55 | { | |
| 56 | unsigned long long ns; | |
| 57 | unsigned long flags; | |
| 58 | ||
| 59 | local_irq_save(flags); | |
| 60 | ns = __cycles_2_ns(cyc); | |
| 61 | local_irq_restore(flags); | |
| 62 | ||
| 63 | return ns; | |
| 64 | } | |
| 688340ea | 65 | |
| 1965aae3 | 66 | #endif /* _ASM_X86_TIMER_H */ |