]> git.baikalelectronics.ru Git - kernel.git/commit
timekeeping: Fix leapsecond triggered load spike issue
authorJohn Stultz <johnstul@us.ibm.com>
Tue, 10 Jul 2012 22:43:20 +0000 (18:43 -0400)
committerThomas Gleixner <tglx@linutronix.de>
Wed, 11 Jul 2012 21:34:37 +0000 (23:34 +0200)
commit2632ac3e0ee46668b2b25fda75f40c944b79867e
tree84479277770c3f02a3580f6d93965fb39f71e1c5
parent23d135673a7bc08e58dd8fae350b3e625289865f
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>
kernel/time/timekeeping.c