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Subject: Re: [PATCH] x86: printk_time to use tsc before cpu_clock is ready
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Ingo Molnar <mingo@elte.hu>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>, Thomas Gleixner <tglx@linutronix.de>,
       "H. Peter Anvin" <hpa@zytor.com>,
       Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org
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Date: Wed, 27 Aug 2008 09:47:13 +0200
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On Wed, 2008-08-27 at 09:42 +0200, Ingo Molnar wrote:
> * Yinghai Lu <yhlu.kernel@gmail.com> wrote:
> 
> > +static unsigned long long tsc_clock(int cpu)
> > +{
> > +	unsigned long long t;
> > +
> > +	rdtscll(t);
> > +
> > +	return t;
> > +}
> 
> hm, i'm not sure i like the whole direction - this reintroduces 
> printk_clock in essence.
> 
> how about initializing cpu_clock() sooner, so that printk timestamps 
> start ticking as soon as possible?

which will make some archs quite unhappy iirc, see those arm and ia64
bugs I caused the other day.