This introduces ntp_update_frequency() and deinlines ntp_clear() (as it's not performance critical). ntp_update_frequency() calculates the base tick length using tick_usec and adds a base adjustment, in case the frequency doesn't divide evenly by HZ. Signed-off-by: Roman Zippel --- include/linux/timex.h | 14 ++------------ kernel/time/ntp.c | 50 ++++++++++++++++++++++++++++++++++++++++++++------ kernel/timer.c | 11 ++++------- 3 files changed, 50 insertions(+), 25 deletions(-) Index: linux-2.6-mm/include/linux/timex.h =================================================================== --- linux-2.6-mm.orig/include/linux/timex.h +++ linux-2.6-mm/include/linux/timex.h @@ -218,18 +218,8 @@ extern long time_reftime; /* time at las extern long time_adjust; /* The amount of adjtime left */ extern long time_next_adjust; /* Value for time_adjust at next tick */ -/** - * ntp_clear - Clears the NTP state variables - * - * Must be called while holding a write on the xtime_lock - */ -static inline void ntp_clear(void) -{ - time_adjust = 0; /* stop active adjtime() */ - time_status |= STA_UNSYNC; - time_maxerror = NTP_PHASE_LIMIT; - time_esterror = NTP_PHASE_LIMIT; -} +extern void ntp_clear(void); +extern void ntp_update_frequency(void); /** * ntp_synced - Returns 1 if the NTP status is not UNSYNC Index: linux-2.6-mm/kernel/time/ntp.c =================================================================== --- linux-2.6-mm.orig/kernel/time/ntp.c +++ linux-2.6-mm/kernel/time/ntp.c @@ -21,6 +21,13 @@ void time_interpolator_update(long delta #define time_interpolator_update(x) #endif +/* + * Timekeeping variables + */ +unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */ +unsigned long tick_nsec; /* ACTHZ period (nsec) */ +static u64 tick_length, tick_length_base; + /* Don't completely fail for HZ > 500. */ int tickadj = 500/HZ ? : 1; /* microsecs */ @@ -43,6 +50,36 @@ long time_reftime; /* time at last adj long time_adjust; long time_next_adjust; +/** + * ntp_clear - Clears the NTP state variables + * + * Must be called while holding a write on the xtime_lock + */ +void ntp_clear(void) +{ + time_adjust = 0; /* stop active adjtime() */ + time_status |= STA_UNSYNC; + time_maxerror = NTP_PHASE_LIMIT; + time_esterror = NTP_PHASE_LIMIT; + + ntp_update_frequency(); + + tick_length = tick_length_base; +} + +#define CLOCK_TICK_OVERFLOW (LATCH * HZ - CLOCK_TICK_RATE) +#define CLOCK_TICK_ADJUST (((s64)CLOCK_TICK_OVERFLOW * NSEC_PER_SEC) / CLOCK_TICK_RATE) + +void ntp_update_frequency(void) +{ + tick_length_base = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << TICK_LENGTH_SHIFT; + tick_length_base += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT; + + do_div(tick_length_base, HZ); + + tick_nsec = tick_length_base >> TICK_LENGTH_SHIFT; +} + /* * this routine handles the overflow of the microsecond field * @@ -157,6 +194,7 @@ void second_overflow(void) */ time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7); #endif + tick_length = tick_length_base; } /* @@ -210,14 +248,13 @@ void update_ntp_one_tick(void) */ u64 current_tick_length(void) { - long delta_nsec; u64 ret; /* calculate the finest interval NTP will allow. * ie: nanosecond value shifted by (SHIFT_SCALE - 10) */ - delta_nsec = tick_nsec + adjtime_adjustment() * 1000; - ret = (u64)delta_nsec << TICK_LENGTH_SHIFT; + ret = tick_length; + ret += (u64)(adjtime_adjustment() * 1000) << TICK_LENGTH_SHIFT; ret += (s64)time_adj << (TICK_LENGTH_SHIFT - (SHIFT_SCALE - 10)); return ret; @@ -357,10 +394,11 @@ int do_adjtimex(struct timex *txc) time_freq = max(time_freq, -time_tolerance); } /* STA_PLL */ } /* txc->modes & ADJ_OFFSET */ - if (txc->modes & ADJ_TICK) { + if (txc->modes & ADJ_TICK) tick_usec = txc->tick; - tick_nsec = TICK_USEC_TO_NSEC(tick_usec); - } + + if (txc->modes & ADJ_TICK) + ntp_update_frequency(); } /* txc->modes */ leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0) result = TIME_ERROR; Index: linux-2.6-mm/kernel/timer.c =================================================================== --- linux-2.6-mm.orig/kernel/timer.c +++ linux-2.6-mm/kernel/timer.c @@ -568,12 +568,6 @@ found: /******************************************************************/ -/* - * Timekeeping variables - */ -unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */ -unsigned long tick_nsec = TICK_NSEC; /* ACTHZ period (nsec) */ - /* * The current time * wall_to_monotonic is what we need to add to xtime (or xtime corrected @@ -763,10 +757,13 @@ void __init timekeeping_init(void) unsigned long flags; write_seqlock_irqsave(&xtime_lock, flags); + + ntp_clear(); + clock = clocksource_get_next(); clocksource_calculate_interval(clock, tick_nsec); clock->cycle_last = clocksource_read(clock); - ntp_clear(); + write_sequnlock_irqrestore(&xtime_lock, flags); } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/