Commit-ID: bf2ac312195155511a0f79325515cbb61929898a Gitweb: http://git.kernel.org/tip/bf2ac312195155511a0f79325515cbb61929898a Author: John Stultz <[email protected]> AuthorDate: Tue, 21 Aug 2012 20:30:49 -0400 Committer: Thomas Gleixner <[email protected]> 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 <[email protected]> Cc: Prarit Bhargava <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Thomas Gleixner <[email protected]> --- 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-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
