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Subject: Re: [patch 12/16] sched: prevent interactions with throttled
 entities
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Paul Turner <pjt@google.com>
Cc: linux-kernel@vger.kernel.org, Bharata B Rao <bharata@linux.vnet.ibm.com>,
        Dhaval Giani <dhaval.giani@gmail.com>,
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        Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
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        Ingo Molnar <mingo@elte.hu>, Pavel Emelyanov <xemul@openvz.org>
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Date: Thu, 23 Jun 2011 13:49:19 +0200
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On Tue, 2011-06-21 at 00:17 -0700, Paul Turner wrote:
> @@ -2635,8 +2704,10 @@ static int update_shares_cpu(struct task
>  
>         raw_spin_lock_irqsave(&rq->lock, flags);
>  
> -       update_rq_clock(rq);
> -       update_cfs_load(cfs_rq, 1);
> +       if (!throttled_hierarchy(cfs_rq)) {
> +               update_rq_clock(rq);
> +               update_cfs_load(cfs_rq, 1);
> +       }
>  
>         /* 

OK, so we can't contribute to load since we're throttled, but
tg->load_weight might have changed meanwhile?

Also, update_cfs_shares()->reweight_entity() can dequeue/enqueue the
entity, doesn't that require an up-to-date rq->clock?