X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=include%2Flinux%2Ftimex.h;h=94f8faecdcbc75bc9a10ffc9fb2a97465480b76e;hb=5ad6468801d28c4d4ac9f48ec19297817c915f6a;hp=fc6035d29d568a018e5c43f6575e5b860379fa96;hpb=7dffa3c673fbcf835cd7be80bb4aec8ad3f51168;p=safe%2Fjmp%2Flinux-2.6 diff --git a/include/linux/timex.h b/include/linux/timex.h index fc6035d..94f8fae 100644 --- a/include/linux/timex.h +++ b/include/linux/timex.h @@ -53,47 +53,11 @@ #ifndef _LINUX_TIMEX_H #define _LINUX_TIMEX_H -#include #include -#include - #define NTP_API 4 /* NTP API version */ /* - * SHIFT_KG and SHIFT_KF establish the damping of the PLL and are chosen - * for a slightly underdamped convergence characteristic. SHIFT_KH - * establishes the damping of the FLL and is chosen by wisdom and black - * art. - * - * MAXTC establishes the maximum time constant of the PLL. With the - * SHIFT_KG and SHIFT_KF values given and a time constant range from - * zero to MAXTC, the PLL will converge in 15 minutes to 16 hours, - * respectively. - */ -#define SHIFT_PLL 4 /* PLL frequency factor (shift) */ -#define SHIFT_FLL 2 /* FLL frequency factor (shift) */ -#define MAXTC 10 /* maximum time constant (shift) */ - -/* - * SHIFT_USEC defines the scaling (shift) of the time_freq and - * time_tolerance variables, which represent the current frequency - * offset and maximum frequency tolerance. - */ -#define SHIFT_USEC 16 /* frequency offset scale (shift) */ -#define PPM_SCALE (NSEC_PER_USEC << (NTP_SCALE_SHIFT - SHIFT_USEC)) -#define PPM_SCALE_INV_SHIFT 20 -#define PPM_SCALE_INV ((1ll << (PPM_SCALE_INV_SHIFT + NTP_SCALE_SHIFT)) / \ - PPM_SCALE + 1) - -#define MAXPHASE 500000000l /* max phase error (ns) */ -#define MAXFREQ 500000 /* max frequency error (ns/s) */ -#define MAXFREQ_SCALED ((s64)MAXFREQ << NTP_SCALE_SHIFT) -#define MINSEC 256 /* min interval between updates (s) */ -#define MAXSEC 2048 /* max interval between updates (s) */ -#define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_USEC) << 5) /* beyond max. dispersion */ - -/* * syscall interface - used (mainly by NTP daemon) * to discipline kernel clock oscillator */ @@ -141,16 +105,26 @@ struct timex { #define ADJ_MICRO 0x1000 /* select microsecond resolution */ #define ADJ_NANO 0x2000 /* select nanosecond resolution */ #define ADJ_TICK 0x4000 /* tick value */ + +#ifdef __KERNEL__ +#define ADJ_ADJTIME 0x8000 /* switch between adjtime/adjtimex modes */ +#define ADJ_OFFSET_SINGLESHOT 0x0001 /* old-fashioned adjtime */ +#define ADJ_OFFSET_READONLY 0x2000 /* read-only adjtime */ +#else #define ADJ_OFFSET_SINGLESHOT 0x8001 /* old-fashioned adjtime */ -#define ADJ_OFFSET_SS_READ 0xa001 /* read-only adjtime */ +#define ADJ_OFFSET_SS_READ 0xa001 /* read-only adjtime */ +#endif -/* xntp 3.4 compatibility names */ +/* NTP userland likes the MOD_ prefix better */ #define MOD_OFFSET ADJ_OFFSET #define MOD_FREQUENCY ADJ_FREQUENCY #define MOD_MAXERROR ADJ_MAXERROR #define MOD_ESTERROR ADJ_ESTERROR #define MOD_STATUS ADJ_STATUS #define MOD_TIMECONST ADJ_TIMECONST +#define MOD_TAI ADJ_TAI +#define MOD_MICRO ADJ_MICRO +#define MOD_NANO ADJ_NANO /* @@ -192,9 +166,66 @@ struct timex { #define TIME_BAD TIME_ERROR /* bw compat */ #ifdef __KERNEL__ +#include +#include +#include + #include /* + * SHIFT_PLL is used as a dampening factor to define how much we + * adjust the frequency correction for a given offset in PLL mode. + * It also used in dampening the offset correction, to define how + * much of the current value in time_offset we correct for each + * second. Changing this value changes the stiffness of the ntp + * adjustment code. A lower value makes it more flexible, reducing + * NTP convergence time. A higher value makes it stiffer, increasing + * convergence time, but making the clock more stable. + * + * In David Mills' nanokernel reference implementation SHIFT_PLL is 4. + * However this seems to increase convergence time much too long. + * + * https://lists.ntp.org/pipermail/hackers/2008-January/003487.html + * + * In the above mailing list discussion, it seems the value of 4 + * was appropriate for other Unix systems with HZ=100, and that + * SHIFT_PLL should be decreased as HZ increases. However, Linux's + * clock steering implementation is HZ independent. + * + * Through experimentation, a SHIFT_PLL value of 2 was found to allow + * for fast convergence (very similar to the NTPv3 code used prior to + * v2.6.19), with good clock stability. + * + * + * SHIFT_FLL is used as a dampening factor to define how much we + * adjust the frequency correction for a given offset in FLL mode. + * In David Mills' nanokernel reference implementation SHIFT_FLL is 2. + * + * MAXTC establishes the maximum time constant of the PLL. + */ +#define SHIFT_PLL 2 /* PLL frequency factor (shift) */ +#define SHIFT_FLL 2 /* FLL frequency factor (shift) */ +#define MAXTC 10 /* maximum time constant (shift) */ + +/* + * SHIFT_USEC defines the scaling (shift) of the time_freq and + * time_tolerance variables, which represent the current frequency + * offset and maximum frequency tolerance. + */ +#define SHIFT_USEC 16 /* frequency offset scale (shift) */ +#define PPM_SCALE ((s64)NSEC_PER_USEC << (NTP_SCALE_SHIFT - SHIFT_USEC)) +#define PPM_SCALE_INV_SHIFT 19 +#define PPM_SCALE_INV ((1LL << (PPM_SCALE_INV_SHIFT + NTP_SCALE_SHIFT)) / \ + PPM_SCALE + 1) + +#define MAXPHASE 500000000L /* max phase error (ns) */ +#define MAXFREQ 500000 /* max frequency error (ns/s) */ +#define MAXFREQ_SCALED ((s64)MAXFREQ << NTP_SCALE_SHIFT) +#define MINSEC 256 /* min interval between updates (s) */ +#define MAXSEC 2048 /* max interval between updates (s) */ +#define NTP_PHASE_LIMIT ((MAXPHASE / NSEC_PER_USEC) << 5) /* beyond max. dispersion */ + +/* * kernel variables * Note: maximum error = NTP synch distance = dispersion + delay / 2; * estimated error = NTP dispersion. @@ -233,11 +264,7 @@ static inline int ntp_synced(void) #define NTP_SCALE_SHIFT 32 -#ifdef CONFIG_NO_HZ -#define NTP_INTERVAL_FREQ (2) -#else #define NTP_INTERVAL_FREQ (HZ) -#endif #define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ) /* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */ @@ -252,6 +279,9 @@ extern int do_adjtimex(struct timex *); int read_current_timer(unsigned long *timer_val); +/* The clock frequency of the i8253/i8254 PIT */ +#define PIT_TICK_RATE 1193182ul + #endif /* KERNEL */ #endif /* LINUX_TIMEX_H */