From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757219Ab2HOULq (ORCPT ); Wed, 15 Aug 2012 16:11:46 -0400 Received: from mail.windriver.com ([147.11.1.11]:37028 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756934Ab2HOTv5 (ORCPT ); Wed, 15 Aug 2012 15:51:57 -0400 From: Paul Gortmaker To: , CC: John Stultz , Thomas Gleixner , Prarit Bhargava , Paul Gortmaker Subject: [v2.6.34-stable 114/165] timekeeping: Fix leapsecond triggered load spike issue Date: Wed, 15 Aug 2012 15:47:38 -0400 Message-ID: <1345060109-9187-115-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.12.rc2 In-Reply-To: <1345060109-9187-1-git-send-email-paul.gortmaker@windriver.com> References: <1345060109-9187-1-git-send-email-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: John Stultz ------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. ------------------- commit 4873fa070ae84a4115f0b3c9dfabc224f1bc7c51 upstream. 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 Reported-by: Jan Engelhardt Reviewed-by: Ingo Molnar Acked-by: Peter Zijlstra Acked-by: Prarit Bhargava 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 Cc: Prarit Bhargava Cc: Thomas Gleixner Cc: Linux Kernel Signed-off-by: John Stultz Signed-off-by: Paul Gortmaker --- kernel/time/timekeeping.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index adfa89d..634c9ee 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -769,6 +769,8 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift) leap = second_overflow(xtime.tv_sec); xtime.tv_sec += leap; wall_to_monotonic.tv_sec -= leap; + if (leap) + clock_was_set_delayed(); } /* Accumulate into raw time */ -- 1.7.12.rc2