Subject: Re: [BUG] cpu-hotplug: Can't offline the CPU with
	naughty	realtime	processes
From: Rusty Russell <rusty@rustcorp.com.au>
To: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
       Srivatsa Vaddagiri <vatsa@in.ibm.com>,
       Zwane Mwaikambo <zwane@arm.linux.org.uk>,
       Nathan Lynch <nathanl@austin.ibm.com>,
       Joel Schopp <jschopp@austin.ibm.com>, Ashok Raj <ashok.raj@intel.com>,
       Heiko Carstens <heiko.carstens@de.ibm.com>,
       Gautham R Shenoy <ego@in.ibm.com>
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Date: Tue, 08 May 2007 14:04:06 +1000
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On Tue, 2007-05-08 at 12:29 +0900, Satoru Takeuchi wrote:
> At Tue, 08 May 2007 13:02:25 +1000,
> Rusty Russell wrote:
> > We used to be able to create kernel threads higher than any userspace
> > priority.  If this is no longer true, I think that's OK: equal priority
> > still means we'll get scheduled, right?
> 
> IF SCHED_RR, yes. However, if SCHED_FIFO, no. Such process doen't have timeslice
> and only relinquish CPU time voluntarily.
> 
> # Hence this problem is complicated ;-(

OK, well, I agree with "don't do that" then 8)

Thanks,
Rusty.

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