linux-kernel - Re: [PATCH 0/2][RFC] Potential fix for leapsecond caused futex issue (v2)

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Date:	Sun, 1 Jul 2012 20:47:33 +0200 (CEST)
From:	Jan Engelhardt <jengelh@...i.de>
To:	John Stultz <johnstul@...ibm.com>
cc:	Linux Kernel <linux-kernel@...r.kernel.org>,
	John Stultz <john.stultz@...aro.org>,
	Prarit Bhargava <prarit@...hat.com>, stable@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 0/2][RFC] Potential fix for leapsecond caused futex issue
 (v2)


On Sunday 2012-07-01 20:29, John Stultz wrote:
>
>An apparent  workaround for this issue is running:
>$ date -s "`date`"
>
>Credit: http://www.sheeri.com/content/mysql-and-leap-second-high-cpu-and-fix

One can run the date call even while ntpd keeps running.

>TODOs:
>* Chase down the futex/hrtimer interaction to see if this could
>be triggered in any other way.
>* Get Tglx's input/ack
>* Generate a backport for pre-v3.4 kernels

It looks like 2.6.37.6 is not affected (on a system where ntpd is 
running). That is to say, at least the mysqld instance on such a system 
did not jump to high CPU usage. I did not try your testcase.c there, 
since that would likely freak out the webapps - or the management.

Other reports on IRC include that 2.6.32-71.el6 (RHEL) is affected. 
(Backporting gone wrong, *snicker* ;)
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