linux-kernel - Re: [RFC][-mm] Add an owner to the mm

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Message-ID: <47F32A6B.1070709@linux.vnet.ibm.com>
Date:	Wed, 02 Apr 2008 12:10:43 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
CC:	Paul Menage <menage@...gle.com>,
	Pavel Emelianov <xemul@...nvz.org>,
	Hugh Dickins <hugh@...itas.com>,
	Sudhir Kumar <skumar@...ux.vnet.ibm.com>,
	YAMAMOTO Takashi <yamamoto@...inux.co.jp>, lizf@...fujitsu.com,
	linux-kernel@...r.kernel.org, taka@...inux.co.jp,
	linux-mm@...ck.org, David Rientjes <rientjes@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC][-mm] Add an owner to the mm_struct (v4)

KAMEZAWA Hiroyuki wrote:
> On Wed, 02 Apr 2008 08:55:34 +0530
> Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
> 
>>>> +	/*
>>>> +	 * Search through everything else. We should not get
>>>> +	 * here often
>>>> +	 */
>>>> +	do_each_thread(g, c) {
>>>> +		if (c->mm == mm)
>>>> +			goto assign_new_owner;
>>>> +	} while_each_thread(g, c);
>>> Doing above in synchronized manner seems too heavy.
>>> When this happen ? or Can this be done in lazy "on-demand" manner ?
>>>
>> Do you mean under task_lock()?
>>
> No, scanning itself. 
> How rarely this scan happens under a server which has 10000- threads ?
> 

This routine will be called every time a thread exits, but will quickly exit
after checking mm_need_new_owner()


-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL
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