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

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Message-ID: <47FDD947.8020600@linux.vnet.ibm.com>
Date:	Thu, 10 Apr 2008 14:39:27 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	Paul Menage <menage@...gle.com>
CC:	Pavel Emelianov <xemul@...nvz.org>,
	Hugh Dickins <hugh@...itas.com>,
	Sudhir Kumar <skumar@...ux.vnet.ibm.com>,
	YAMAMOTO Takashi <yamamoto@...inux.co.jp>,
	linux-kernel@...r.kernel.org, taka@...inux.co.jp,
	linux-mm@...ck.org, David Rientjes <rientjes@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [-mm] Add an owner to the mm_struct (v8)

Paul Menage wrote:
> On Tue, Apr 8, 2008 at 12:05 AM, Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
>> Paul Menage wrote:
>>  > On Mon, Apr 7, 2008 at 11:52 PM, Balbir Singh <balbir@...ux.vnet.ibm.com> wrote:
>>  >>  I agree, but like I said earlier, this was the easily available ready made
>>  >>  application I found. Do you know of any other highly threaded micro benchmark?
>>  >>
>>  >
>>  > How about a simple program that creates N threads that just sleep,
>>  > then has the main thread exit?
>>  >
>>
>>  That is not really representative of anything. I have that program handy. How do
>>  we measure the impact on throughput?
> 
> It's very representative of how much additional overhead in terms of
> mm->owner churn there is in a large multi-threaded application
> exiting, which is the thing that you're trying to optimize with the
> delayed thread group leader checks.
> 

I see almost no overhead after the notification change optimization (notify only
if owner belongs to a different cgroup).

My program creates n processes with k threads each and forces the thread group
leader to exit. For my experiment I created 10 processes with 800 threads each
(NOTE: you need to change ulimit -s for this to work).

I am going to remove the delay_group_leader() optimization and submit v9.

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