linux-kernel - Re: [PATCH v5] sched/deadline: support dl task migration during cpu hotplug

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Message-ID: <20141120084932.GA3818@kernel>
Date:	Thu, 20 Nov 2014 16:49:32 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@....com>
Cc:	Kirill Tkhai <ktkhai@...allels.com>,
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
	Wanpeng Li <wanpeng.li@...ux.intel.com>
Subject: Re: [PATCH v5] sched/deadline: support dl task migration during cpu
 hotplug

Hi Peterz, Juri,
On Thu, Nov 13, 2014 at 01:21:31PM +0300, Kirill Tkhai wrote:
>> > Also, we should think about the following situation.
>> >
>> > DL task is left on dead rq. In your scheme it will be moved by the timer.
>> > But what will be if somebody changes the class of the task (before timer)?
>> 
>> I think timer will be cancelled in switched_from_dl().
>
>Yeah, but nobody will move this task to alive rq.
>
>> > In this case the task still remains on dead rq.
>> >
>> > We should handle this situation in some way.

I think pang's patch handle the exclusive cpusets rd->span issue, the concern 
which Kirill mentioned above maybe the last one block the patch merged, is 
there any idea or proposal from you experts?

Regards,
Wanpeng Li 

>> >
>> > Kirill
>> >
>> >
>> > --
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