linux-kernel - Re: [patch 11/15] sched: prevent interactions between throttled entities and load-balance

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Message-ID: <4DC8E8BA.3010106@jp.fujitsu.com>
Date:	Tue, 10 May 2011 16:26:50 +0900
From:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
To:	Paul Turner <pjt@...gle.com>
CC:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Bharata B Rao <bharata@...ux.vnet.ibm.com>,
	Dhaval Giani <dhaval.giani@...il.com>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
	Srivatsa Vaddagiri <vatsa@...ibm.com>,
	Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...e.hu>, Pavel Emelyanov <xemul@...nvz.org>
Subject: Re: [patch 11/15] sched: prevent interactions between throttled entities
 and load-balance

(2011/05/03 18:28), Paul Turner wrote:
>>>From the perspective of load-balance and shares distribution, throttled
> entities should be invisible.
> 
> However, both of these operations work on 'active' lists and are not
> inherently aware of what group hierarchies may be present.  In some cases this
> may be side-stepped (e.g. we could sideload via tg_load_down in load balance) 
> while in others (e.g. update_shares()) it is more difficult to compute without
> incurring some O(n^2) costs.
> 
> Instead, track hierarchal throttled state at time of transition.  This allows

                 hierarchical

> us to easily identify whether an entity belongs to a throttled hierarchy and
> avoid incorrect interactions with it.
> 
> Also, when an entity leaves a throttled hierarchy we need to advance its
> time averaging for shares averaging so that the elapsed throttled time is not
> considered as part of the cfs_rq's operation.
> 
> Signed-off-by: Paul Turner <pjt@...gle.com>
> ---

Reviewed-by: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>

Thanks,
H.Seto

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