Commit fdcedf7b authored Feb 18, 2009 by john stultz Committed by Ingo Molnar Feb 19, 2009

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 <johnstul@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent ba95fd47

kernel/time/ntp.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -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)

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