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authorJohn Stultz <john.stultz@linaro.org>2012-08-22 04:30:49 +0400
committerThomas Gleixner <tglx@linutronix.de>2012-08-22 12:42:13 +0400
commitbf2ac312195155511a0f79325515cbb61929898a (patch)
tree514057045cf52d3da13f551661131fd102f67376 /kernel/time
parent6ea565a9be32a3c8d1092017686f183b6d8c4514 (diff)
downloadlinux-bf2ac312195155511a0f79325515cbb61929898a.tar.xz
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@linaro.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1345595449-34965-5-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/timekeeping.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index a5a9389c4c30..0c1485e42be6 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,