Subject: Re: [patch] sched_clock(): cleanups, #2
From: Daniel Walker <dwalker@mvista.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>, Ingo Molnar <mingo@elte.hu>,
       Satyam Sharma <satyam.sharma@gmail.com>, linux-kernel@vger.kernel.org,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>
In-Reply-To: <20070525091743.5fb569a8.akpm@linux-foundation.org>
References: <20070525015544.bce3cb99.akpm@linux-foundation.org>
	 <20070525090315.GK8094@one.firstfloor.org> <20070525091928.GA3177@elte.hu>
	 <20070525094640.GL8094@one.firstfloor.org> <20070525101248.GA7547@elte.hu>
	 <20070525112020.GN8094@one.firstfloor.org> <20070525112600.GA27007@elte.hu>
	 <20070525115004.GA4574@elte.hu> <20070525115544.GP8094@one.firstfloor.org>
	 <20070525120228.GA7186@elte.hu> <20070525121540.GA24083@one.firstfloor.org>
	 <20070525091743.5fb569a8.akpm@linux-foundation.org>
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Date: Fri, 25 May 2007 09:26:14 -0700
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On Fri, 2007-05-25 at 09:17 -0700, Andrew Morton wrote:
> On Fri, 25 May 2007 14:15:40 +0200 Andi Kleen <andi@firstfloor.org> wrote:
> 
> > -Andi (who hopes this thread will end soon now and we can all go
> > back to more important issues)
> 
> fyi, the thread has been damn useful for me.  If Ingo hadn't spotted that
> preempt_count() imbalance then there's a decent chance that I'd have been
> the first to hit it.
> 
> Time to bisect 1,000 patches: maybe an hour, if I choose the x86 tree as
> the first pivot point, which is likely.
> 
> Or I wouldn't have hit it, in which case a tester hits it, and someone
> (guess who) gets to enter into an intercontinental head-scratching session
> trying to work out who broke it this time, consuming the tester's time too.
> Plus we have a wrecked -mm and other people's code doesn't get as
> well-tested as it might.
> 
> All for one silly little mistake.

I wonder if this was the source of the lockdep selftest failures, or the
mystery hang this patch caused (IIRC)..

Daniel

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