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Date: Tue, 24 Apr 2007 09:24:08 +0200
From: Ingo Molnar <mingo@elte.hu>
To: David Lang <david.lang@digitalinsight.com>
Cc: Gene Heskett <gene.heskett@gmail.com>,
       Peter Williams <pwil3058@bigpond.net.au>,
       Arjan van de Ven <arjan@infradead.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Nick Piggin <npiggin@suse.de>, Juliusz Chroboczek <jch@pps.jussieu.fr>,
       Con Kolivas <kernel@kolivas.org>, ck list <ck@vds.kolivas.org>,
       Bill Davidsen <davidsen@tmr.com>, Willy Tarreau <w@1wt.eu>,
       William Lee Irwin III <wli@holomorphy.com>,
       linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
       Mike Galbraith <efault@gmx.de>, Thomas Gleixner <tglx@linutronix.de>,
       caglar@pardus.org.tr
Subject: Re: [REPORT] cfs-v4 vs sd-0.44
Message-ID: <20070424072408.GA27769@elte.hu>
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* David Lang <david.lang@digitalinsight.com> wrote:

> > (Btw., to protect against such mishaps in the future i have changed 
> > the SysRq-N [SysRq-Nice] implementation in my tree to not only 
> > change real-time tasks to SCHED_OTHER, but to also renice negative 
> > nice levels back to 0 - this will show up in -v6. That way you'd 
> > only have had to hit SysRq-N to get the system out of the wedge.)
> 
> if you are trying to unwedge a system it may be a good idea to renice 
> all tasks to 0, it could be that a task at +19 is holding a lock that 
> something else is waiting for.

Yeah, that's possible too, but +19 tasks are getting a small but 
guaranteed share of the CPU so eventually it ought to release it. It's 
still a possibility, but i think i'll wait for a specific incident to 
happen first, and then react to that incident :-)

	Ingo