From fdcedf7b75808dd72c3cc0b931be11b04d75c60a Mon Sep 17 00:00:00 2001 From: john stultz Date: Wed, 18 Feb 2009 16:02:22 -0800 Subject: time: apply NTP frequency/tick changes immediately Since the GENERIC_TIME changes landed, the adjtimex behavior changed for struct timex.tick and .freq changed. When the tick or freq value is set, we adjust the tick_length_base in ntp_update_frequency(). However, this new value doesn't get applied to tick_length until the next second (via second_overflow). This means some applications that do quick time tweaking do not see the requested change made as quickly as expected. I've run a few tests with this change, and ntpd still functions fine. Signed-off-by: John Stultz Signed-off-by: Ingo Molnar --- kernel/time/ntp.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel/time/ntp.c') diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index f5f793d9241..e1fa3689a90 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -51,6 +51,7 @@ static long ntp_tick_adj; static void ntp_update_frequency(void) { + u64 old_tick_length_base = tick_length_base; u64 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << NTP_SCALE_SHIFT; second_length += (s64)ntp_tick_adj << NTP_SCALE_SHIFT; @@ -60,6 +61,12 @@ static void ntp_update_frequency(void) tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT; tick_length_base = div_u64(tick_length_base, NTP_INTERVAL_FREQ); + + /* + * Don't wait for the next second_overflow, apply + * the change to the tick length immediately + */ + tick_length += tick_length_base - old_tick_length_base; } static void ntp_update_offset(long offset) -- cgit v1.2.3-70-g09d2