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Subject: Re: Why does the 2.6.37 scheduler hate RT tasks?
From: Peter Zijlstra <peterz@infradead.org>
To: paulmck@linux.vnet.ibm.com
Cc: linux-kernel@vger.kernel.org
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References: <20110202011049.GA15084@linux.vnet.ibm.com>
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Date: Wed, 02 Feb 2011 12:14:25 +0100
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On Tue, 2011-02-01 at 17:10 -0800, Paul E. McKenney wrote:
> Hello, Peter,
> 
> If I create an SCHED_FIFO-priority kthread in pre-2.6.37 kernels,
> things work nicely.  If I try in in later kernels, __disable_runtime()
> gets upset occasionally during CPU-hotplug calls when CPUs are inserted.
> If I make the exact same kthreads run SCHED_NORMAL, no problem.

> PS.  The code at kernel/sched_rt.c:466 is "BUG_ON(want);" in
>      __disable_runtime().  Config attached in case that helps.

Hrmm.. weird.. ok I'll have a look at that.