linux-kernel - Re: [PATCH 2/3] [RFC] time: Fix leapsecond triggered hrtimer/futex load spike issue

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Date:	Thu, 05 Jul 2012 10:29:32 -0400
From:	Prarit Bhargava <prarit@...hat.com>
To:	John Stultz <johnstul@...ibm.com>
CC:	Linux Kernel <linux-kernel@...r.kernel.org>,
	stable@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	linux@...nhuawei.org
Subject: Re: [PATCH 2/3] [RFC] time: Fix leapsecond triggered hrtimer/futex
 load spike issue



On 07/04/2012 02:21 AM, John Stultz wrote:
> 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 <prarit@...hat.com>
> CC: stable@...r.kernel.org
> CC: Thomas Gleixner <tglx@...utronix.de>
> CC: linux@...nhuawei.org
> Reported-by: Jan Engelhardt <jengelh@...i.de>
> Signed-off-by: John Stultz <johnstul@...ibm.com>


Acked-by: Prarit Bhargava <prarit@...hat.com>

P.
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