From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: John Stultz To: Linux Kernel Cc: John Stultz , Prarit Bhargava , stable@vger.kernel.org, Thomas Gleixner Subject: [PATCH 2/3] time: Fix leapsecond triggered hrtimer/futex load spike issue Date: Thu, 5 Jul 2012 15:12:17 -0400 Message-Id: <1341515538-5100-3-git-send-email-johnstul@us.ibm.com> In-Reply-To: <1341515538-5100-1-git-send-email-johnstul@us.ibm.com> References: <1341515538-5100-1-git-send-email-johnstul@us.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: As widely reported on the internet, some Linux systems after the leapsecond was inserted are experiencing futex related load spikes (usually connected to MySQL, Firefox, Thunderbird, Java, etc). An apparent for this issue workaround is running: $ date -s "`date`" Credit: http://www.sheeri.com/content/mysql-and-leap-second-high-cpu-and-fix I this issue is due to the leapsecond being added without calling clock_was_set() to notify the hrtimer subsystem of the change. The workaround functions as it forces a clock_was_set() call from settimeofday(). This fix adds the required clock_was_set() calls to where we adjust for leapseconds. NOTE: This fix *depends* on the previous fix, which allows clock_was_set to be called from atomic context. Do not try to apply just this patch. CC: Prarit Bhargava CC: stable@vger.kernel.org CC: Thomas Gleixner Acked-by: Prarit Bhargava Reported-by: Jan Engelhardt Signed-off-by: John Stultz --- kernel/time/timekeeping.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 6f46a00..cc2991d 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(); } /* 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(); } timekeeping_update(false); -- 1.7.9.5