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Date: Wed, 22 Jun 2011 18:38:36 +0900
From: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
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To: Paul Turner <pjt@google.com>
CC: linux-kernel@vger.kernel.org, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Bharata B Rao <bharata@linux.vnet.ibm.com>,
        Dhaval Giani <dhaval.giani@gmail.com>,
        Balbir Singh <balbir@linux.vnet.ibm.com>,
        Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
        Srivatsa Vaddagiri <vatsa@in.ibm.com>,
        Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
        Ingo Molnar <mingo@elte.hu>, Pavel Emelyanov <xemul@openvz.org>
Subject: Re: [patch 06/16] sched: add a timer to handle CFS bandwidth refresh
References: <20110621071649.862846205@google.com> <20110621071700.284687900@google.com>
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(2011/06/21 16:16), Paul Turner wrote:
> This patch adds a per-task_group timer which handles the refresh of the global
> CFS bandwidth pool.
> 
> Since the RT pool is using a similar timer there's some small refactoring to
> share this support.
> 
> Signed-off-by: Paul Turner <pjt@google.com>
> Reviewed-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
> 
> ---
(snip)
> @@ -413,8 +444,26 @@ static void init_cfs_rq_runtime(struct c
>  	cfs_rq->runtime_enabled = 0;
>  }
>  
> +/* requires cfs_b->lock */
> +static void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
> +{
> +	/*
> +	 * Handle the extremely unlikely case of trying to start the period
> +	 * timer, while that timer is in the tear-down path from having
> +	 * decided to no longer run.  In this case we must wait for the
> +	 * (tail of the) callback to terminate so that we can re-enqueue it.
> +	 */
> +	if (unlikely(hrtimer_active(&cfs_b->period_timer)))
> +		hrtimer_cancel(&cfs_b->period_timer);
> +
> +	cfs_b->timer_active = 1;
> +	start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period);
> +}
> +

Nice trick :-)

(Again,)
Reviewed-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>


Thanks,
H.Seto