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Subject: Re: [PATCH 2.6.27-rc5 resubmit] Fix itimer/many thread hang.
From: Frank Mayhar <fmayhar@google.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
       Roland McGrath <roland@redhat.com>,
       Thomas Gleixner <tglx@linutronix.de>,
       Alexey Dobriyan <adobriyan@gmail.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Oleg Nesterov <oleg@tv-sign.ru>
In-Reply-To: <20080914150923.GB26984@elte.hu>
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	 <20080914150651.GK12522@elte.hu>  <20080914150923.GB26984@elte.hu>
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Date: Mon, 15 Sep 2008 11:09:02 -0700
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On Sun, 2008-09-14 at 17:09 +0200, Ingo Molnar wrote:
> the patch wasnt built on UP i guess - see the fix below.

Yeah, I've been focusing so much on getting the SMP case right that I've
been neglecting UP a bit.

> the wider question is, shouldnt the UP case be just the same as the SMP 
> case? Especially the type assymetry struct thread_group_cputime looks 
> ugly. (and assymetries like that tend to be a constant source of 
> breakage like the one below.)

I'm not overly fond of this one, either; I did it at Roland's suggestion
(it's all _his_ fault, yeah, _that's_ the ticket! :-); his opinion IIRC
was that the UP case will perform better without the extra pointer
dereferences.  I agree that it's a potential source of pain such as the
one you point out.
-- 
Frank Mayhar <fmayhar@google.com>
Google, Inc.