linux-kernel - Re: cpu_clock confusion (was: printk time confusion?)

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Message-Id: <1209028912.3357.52.camel@johannes.berg>
Date:	Thu, 24 Apr 2008 11:21:52 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Benjamin Herrenschmidt <benh@...abs.org>,
	linuxppc-dev list <linuxppc-dev@...abs.org>,
	Arnd Bergmann <arndb@...ibm.com>,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: cpu_clock confusion (was: printk time confusion?)


> > [    2.764009 (3/3)]
> > [    4.272241 (2/2)]
> > [    4.272322 (2/2)]
> > [    4.272375 (2/2)]
> > [    2.948002 (3/3)]
> > 
> > As you can see, I added printk_cpu and smp_processor_id() to the 
> > printk timestamp output and thus it is obvious that the different 
> > times come from different CPUs.
> 
> the fixes are queued for v2.6.26. You can pick them up from 
> sched-devel/latest as well:
> 
>   http://people.redhat.com/mingo/sched-devel.git/README

Hmm. Why is that whole cpu_clock stuff in place anyway? powerpc has
perfectly synchronised time across processors with dirt cheap access to
it as well, so why build all this code that only messes it up on top of
it?

johannes

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