Home Home > GIT Browse
summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJohn Stultz <johnstul@us.ibm.com>2012-07-10 18:43:20 -0400
committerThomas Gleixner <tglx@linutronix.de>2012-07-11 23:34:37 +0200
commit4873fa070ae84a4115f0b3c9dfabc224f1bc7c51 (patch)
tree84479277770c3f02a3580f6d93965fb39f71e1c5
parentf55a6faa384304c89cfef162768e88374d3312cb (diff)
timekeeping: Fix leapsecond triggered load spike issue
The timekeeping code misses an update of the hrtimer subsystem after a leap second happened. Due to that timers based on CLOCK_REALTIME are either expiring a second early or late depending on whether a leap second has been inserted or deleted until an operation is initiated which causes that update. Unless the update happens by some other means this discrepancy between the timekeeping and the hrtimer data stays forever and timers are expired either early or late. The reported immediate workaround - $ data -s "`date`" - is causing a call to clock_was_set() which updates the hrtimer data structures. See: http://www.sheeri.com/content/mysql-and-leap-second-high-cpu-and-fix Add the missing clock_was_set() call to update_wall_time() in case of a leap second event. The actual update is deferred to softirq context as the necessary smp function call cannot be invoked from hard interrupt context. Signed-off-by: John Stultz <johnstul@us.ibm.com> Reported-by: Jan Engelhardt <jengelh@inai.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Prarit Bhargava <prarit@redhat.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1341960205-56738-3-git-send-email-johnstul@us.ibm.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-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 6f46a00a1e8a..a413e5940e06 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -963,6 +963,8 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
leap = second_overflow(timekeeper.xtime.tv_sec);
timekeeper.xtime.tv_sec += leap;
timekeeper.wall_to_monotonic.tv_sec -= leap;
+ if (leap)
+ clock_was_set_delayed();
}
/* Accumulate raw time */
@@ -1079,6 +1081,8 @@ static void update_wall_time(void)
leap = second_overflow(timekeeper.xtime.tv_sec);
timekeeper.xtime.tv_sec += leap;
timekeeper.wall_to_monotonic.tv_sec -= leap;
+ if (leap)
+ clock_was_set_delayed();
}
timekeeping_update(false);