Date: Tue, 11 Dec 2007 00:04:25 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: rjw@sisk.pl, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
       Stefano Brivio <stefano.brivio@polimi.it>,
       Guillaume Chazarain <guichaz@yahoo.fr>
Subject: Re: 2.6.24-rc4-git5: Reported regressions from 2.6.23
Message-ID: <20071210230425.GA641@elte.hu>
References: <200712080340.49546.rjw@sisk.pl> <20071210204212.GA5502@elte.hu> <20071210125923.37bd2f10.akpm@linux-foundation.org> <20071210224508.GB27178@elte.hu>
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* Ingo Molnar <mingo@elte.hu> wrote:

> * Andrew Morton <akpm@linux-foundation.org> wrote:
> 
> > > what do you think? Right now i've got them queued up for 2.6.25 in 
> > > both the scheduler-devel and the x86-devel git trees - but can 
> > > submit them for 2.6.24 if it's better if we did them there. I've got 
> > > no strong opinion either way.
> > 
> > printk_clock() doesn't seem terribly important but what's this stuff 
> > about effects on udelay/mdelay?  That can be serious if they're 
> > getting shortened.
> 
> since udelay depends on loops_per_jiffy, which is fixed up 
> time_cpufreq_notifier(), i dont see how it could be affected by 
> frequency changes. (but that's the theory - practice might be 
> different)

Stefano Brivio reported udelay()/mdelay() effects in the b43 driver. 
(and it caused driver failures for him.)

Stefano, could you please try to sum up your experiences with that 
issue? Is it reproducable, and the 5 patches i did fix it? (if yes, 
could you try to re-do the mdelay verifications perhaps, to make sure 
it's not some other effect interacting here. In theory sched-clock 
scaling has no effect on udelay behavior.)

	Ingo
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