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Subject: Re: [PATCH] timekeeping: drop irq-context clocksource polling
From: Thomas Gleixner <tglx@linutronix.de>
Reply-To: tglx@linutronix.de
To: Daniel Walker <dwalker@mvista.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
       johnstul@us.ibm.com, mingo@elte.hu
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Date: Sat, 07 Apr 2007 22:50:19 +0200
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On Sat, 2007-04-07 at 10:43 -0700, Daniel Walker wrote:
> Looks like this path ,
> 
> arch/i386/kernel/tsc.c: time_cpufreq_notifier(); <-- takes xtime_lock
> 			 mark_tsc_unstable();
>             		  clocksource_change_rating(&clocksource_tsc, 0);
> 			   timekeeping_change_clocksource(); <-- takes xtime_lock
> 
> 
> I'm not sure why the time_cpufreq_notifier is taking the xtime_lock tho .

Simply because it fiddles with variables which are relevant for
timekeeping.

	tglx