Commit-ID: bf2ac312195155511a0f79325515cbb61929898a Gitweb: http://git.kernel.org/tip/bf2ac312195155511a0f79325515cbb61929898a Author: John Stultz <john.stultz@xxxxxxxxxx> AuthorDate: Tue, 21 Aug 2012 20:30:49 -0400 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Wed, 22 Aug 2012 10:42:13 +0200 time: Avoid making adjustments if we haven't accumulated anything If update_wall_time() is called and the current offset isn't large enough to accumulate, avoid re-calling timekeeping_adjust which may change the clock freq and can cause 1ns inconsistencies with CLOCK_REALTIME_COARSE/CLOCK_MONOTONIC_COARSE. Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> Cc: Prarit Bhargava <prarit@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/1345595449-34965-5-git-send-email-john.stultz@xxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- kernel/time/timekeeping.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index a5a9389..0c1485e 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1152,6 +1152,10 @@ static void update_wall_time(void) offset = (clock->read(clock) - clock->cycle_last) & clock->mask; #endif + /* Check if there's really nothing to do */ + if (offset < tk->cycle_interval) + goto out; + /* * With NO_HZ we may have to accumulate many cycle_intervals * (think "ticks") worth of time at once. To do this efficiently, -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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