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| author | john stultz <johnstul@us.ibm.com> | 2009-02-18 16:02:22 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-02-19 10:10:08 +0100 |
| commit | fdcedf7b75808dd72c3cc0b931be11b04d75c60a (patch) | |
| tree | c64743890ffa9722f8705ce0c214f0f08ffe4d9a /kernel/time | |
| parent | ba95fd47d177d46743ad94055908d22840370e06 (diff) | |
| download | lwn-fdcedf7b75808dd72c3cc0b931be11b04d75c60a.tar.gz lwn-fdcedf7b75808dd72c3cc0b931be11b04d75c60a.zip | |
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>
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/ntp.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index f5f793d92415..e1fa3689a903 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) |