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author | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2007-10-12 21:27:47 -0400 |
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committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2007-10-12 21:27:47 -0400 |
commit | b981d8b3f5e008ff10d993be633ad00564fc22cd (patch) | |
tree | e292dc07b22308912cf6a58354a608b9e5e8e1fd /include/asm-x86/timer.h | |
parent | b11d2127c4893a7315d1e16273bc8560049fa3ca (diff) | |
parent | 2b9e0aae1d50e880c58d46788e5e3ebd89d75d62 (diff) |
Merge master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6
Conflicts:
drivers/macintosh/adbhid.c
Diffstat (limited to 'include/asm-x86/timer.h')
-rw-r--r-- | include/asm-x86/timer.h | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/include/asm-x86/timer.h b/include/asm-x86/timer.h new file mode 100644 index 00000000000..0db7e994fb8 --- /dev/null +++ b/include/asm-x86/timer.h @@ -0,0 +1,50 @@ +#ifndef _ASMi386_TIMER_H +#define _ASMi386_TIMER_H +#include <linux/init.h> +#include <linux/pm.h> + +#define TICK_SIZE (tick_nsec / 1000) + +unsigned long long native_sched_clock(void); +unsigned long native_calculate_cpu_khz(void); + +extern int timer_ack; +extern int no_timer_check; +extern int recalibrate_cpu_khz(void); + +#ifndef CONFIG_PARAVIRT +#define calculate_cpu_khz() native_calculate_cpu_khz() +#endif + +/* Accellerators for sched_clock() + * convert from cycles(64bits) => nanoseconds (64bits) + * basic equation: + * ns = cycles / (freq / ns_per_sec) + * ns = cycles * (ns_per_sec / freq) + * ns = cycles * (10^9 / (cpu_khz * 10^3)) + * ns = cycles * (10^6 / cpu_khz) + * + * Then we use scaling math (suggested by george@mvista.com) to get: + * ns = cycles * (10^6 * SC / cpu_khz) / SC + * ns = cycles * cyc2ns_scale / SC + * + * And since SC is a constant power of two, we can convert the div + * into a shift. + * + * We can use khz divisor instead of mhz to keep a better percision, since + * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. + * (mathieu.desnoyers@polymtl.ca) + * + * -johnstul@us.ibm.com "math is hard, lets go shopping!" + */ +extern unsigned long cyc2ns_scale __read_mostly; + +#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */ + +static inline unsigned long long cycles_2_ns(unsigned long long cyc) +{ + return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR; +} + + +#endif |