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

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Message-ID: <5458F5C8.1030405@arm.com>
Date:	Tue, 04 Nov 2014 15:50:32 +0000
From:	Juri Lelli <juri.lelli@....com>
To:	Peter Zijlstra <peterz@...radead.org>,
	Wanpeng Li <kernellwp@...il.com>
CC:	Wanpeng Li <wanpeng.li@...ux.intel.com>,
	Ingo Molnar <mingo@...hat.com>,
	Kirill Tkhai <ktkhai@...allels.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"juri.lelli@...il.com" <juri.lelli@...il.com>
Subject: Re: [PATCH RFC] sched/deadline: support dl task migrate during cpu
 hotplug

Hi,

On 04/11/14 15:46, Peter Zijlstra wrote:
> On Tue, Nov 04, 2014 at 09:30:46PM +0800, Wanpeng Li wrote:
> 
> 
>> + if (!rq->online) {
>> + struct rq *latest_rq = NULL;
>> + int cpu;
>> + u64 dmin = LONG_MAX;
>> +
>> + for_each_cpu(cpu, &p->cpus_allowed)
>> + if (cpu_online(cpu) &&
>> + cpu_rq(cpu)->dl.earliest_dl.curr < dmin) {
>> + latest_rq = cpu_rq(cpu);
>> + dmin = latest_rq->dl.earliest_dl.curr;
>> + }
> 
> I would have expected something using find_later_rq(), but I might be
> mistaken, I'll let Juri suggest something.
> 

Yeah, we should be able to reuse something that we already have. I'm
actually sorry that I'm not responsive on this, but I'm really busy on
other things this week. I hope to be able to find some time soon to test
this all.

Thanks,

- Juri

>> +
>> + if (!latest_rq)
>> + goto unlock;
>> +
>> + raw_spin_lock(&latest_rq->lock);
>> +
>> + deactivate_task(rq, p, 0);
>> + set_task_cpu(p, latest_rq->cpu);
>> + activate_task(latest_rq, p, 0);
>> +
>> + raw_spin_unlock(&latest_rq->lock);
>> + }
>> +
>> unlock:
>> raw_spin_unlock(&rq->lock);
> 

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