diff options
Diffstat (limited to 'kernel/time/timekeeping.c')
| -rw-r--r-- | kernel/time/timekeeping.c | 33 |
1 files changed, 19 insertions, 14 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 7af45cbf6b1..dfdab1cefe1 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -23,6 +23,8 @@ struct timekeeper { /* Current clocksource used for timekeeping. */ struct clocksource *clock; + /* The shift value of the current clocksource. */ + int shift; /* Number of clock cycles in one NTP interval. */ cycle_t cycle_interval; @@ -36,6 +38,9 @@ struct timekeeper { /* Difference between accumulated time and NTP time in ntp * shifted nano seconds. */ s64 ntp_error; + /* Shift conversion between clock shifted nano seconds and + * ntp shifted nano seconds. */ + int ntp_error_shift; }; struct timekeeper timekeeper; @@ -75,8 +80,10 @@ static void timekeeper_setup_internals(struct clocksource *clock) ((u64) interval * clock->mult_orig) >> clock->shift; timekeeper.xtime_nsec = 0; + timekeeper.shift = clock->shift; timekeeper.ntp_error = 0; + timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift; } /* @@ -641,8 +648,7 @@ static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval, * Now calculate the error in (1 << look_ahead) ticks, but first * remove the single look ahead already included in the error. */ - tick_error = tick_length >> - (NTP_SCALE_SHIFT - timekeeper.clock->shift + 1); + tick_error = tick_length >> (timekeeper.ntp_error_shift + 1); tick_error -= timekeeper.xtime_interval >> 1; error = ((error - tick_error) >> look_ahead) + tick_error; @@ -673,8 +679,7 @@ static void timekeeping_adjust(s64 offset) s64 error, interval = timekeeper.cycle_interval; int adj; - error = timekeeper.ntp_error >> - (NTP_SCALE_SHIFT - timekeeper.clock->shift - 1); + error = timekeeper.ntp_error >> (timekeeper.ntp_error_shift - 1); if (error > interval) { error >>= 2; if (likely(error <= interval)) @@ -696,7 +701,7 @@ static void timekeeping_adjust(s64 offset) timekeeper.xtime_interval += interval; timekeeper.xtime_nsec -= offset; timekeeper.ntp_error -= (interval - offset) << - (NTP_SCALE_SHIFT - timekeeper.clock->shift); + timekeeper.ntp_error_shift; } /** @@ -708,7 +713,7 @@ void update_wall_time(void) { struct clocksource *clock; cycle_t offset; - s64 nsecs; + u64 nsecs; /* Make sure we're fully resumed: */ if (unlikely(timekeeping_suspended)) @@ -720,13 +725,13 @@ void update_wall_time(void) #else offset = timekeeper.cycle_interval; #endif - timekeeper.xtime_nsec = (s64)xtime.tv_nsec << clock->shift; + timekeeper.xtime_nsec = (s64)xtime.tv_nsec << timekeeper.shift; /* normally this loop will run just once, however in the * case of lost or late ticks, it will accumulate correctly. */ while (offset >= timekeeper.cycle_interval) { - u64 nsecps = (u64)NSEC_PER_SEC << clock->shift; + u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift; /* accumulate one interval */ offset -= timekeeper.cycle_interval; @@ -748,7 +753,7 @@ void update_wall_time(void) /* accumulate error between NTP and clock interval */ timekeeper.ntp_error += tick_length; timekeeper.ntp_error -= timekeeper.xtime_interval << - (NTP_SCALE_SHIFT - clock->shift); + timekeeper.ntp_error_shift; } /* correct the clock when NTP error is too big */ @@ -773,16 +778,16 @@ void update_wall_time(void) if (unlikely((s64)timekeeper.xtime_nsec < 0)) { s64 neg = -(s64)timekeeper.xtime_nsec; timekeeper.xtime_nsec = 0; - timekeeper.ntp_error += neg << (NTP_SCALE_SHIFT - clock->shift); + timekeeper.ntp_error += neg << timekeeper.ntp_error_shift; } /* store full nanoseconds into xtime after rounding it up and * add the remainder to the error difference. */ - xtime.tv_nsec = ((s64)timekeeper.xtime_nsec >> clock->shift) + 1; - timekeeper.xtime_nsec -= (s64)xtime.tv_nsec << clock->shift; - timekeeper.ntp_error += timekeeper.xtime_nsec << - (NTP_SCALE_SHIFT - clock->shift); + xtime.tv_nsec = ((s64) timekeeper.xtime_nsec >> timekeeper.shift) + 1; + timekeeper.xtime_nsec -= (s64) xtime.tv_nsec << timekeeper.shift; + timekeeper.ntp_error += timekeeper.xtime_nsec << + timekeeper.ntp_error_shift; nsecs = clocksource_cyc2ns(offset, clock->mult, clock->shift); update_xtime_cache(nsecs); |