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From: Minchan Kim <minchan.kim@gmail.com>
To: Ying Han <yinghan@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>,
	Balbir Singh <balbir@linux.vnet.ibm.com>,
	Tejun Heo <tj@kernel.org>, Pavel Emelyanov <xemul@openvz.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Li Zefan <lizf@cn.fujitsu.com>, Mel Gorman <mel@csn.ul.ie>,
	Christoph Lameter <cl@linux.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Rik van Riel <riel@redhat.com>, Hugh Dickins <hughd@google.com>,
	Michal Hocko <mhocko@suse.cz>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	Zhu Yanhai <zhu.yanhai@gmail.com>,
	linux-mm@kvack.org
Subject: Re: [PATCH 1/3] memcg kswapd thread pool (Was Re: [PATCH V6 00/10] memcg: per cgroup background reclaim
Date: Fri, 22 Apr 2011 10:02:47 +0900	[thread overview]
Message-ID: <BANLkTimnesg21xvoHbP=fC8KJOS0jrxSiA@mail.gmail.com> (raw)
In-Reply-To: <BANLkTi=_-rTst9OH0CSmk=n9LW2jGY5whQ@mail.gmail.com>

On Fri, Apr 22, 2011 at 1:56 AM, Ying Han <yinghan@google.com> wrote:
>
>
> On Thu, Apr 21, 2011 at 2:05 AM, Minchan Kim <minchan.kim@gmail.com> wrote:
>>
>> On Thu, Apr 21, 2011 at 5:46 PM, KAMEZAWA Hiroyuki
>> <kamezawa.hiroyu@jp.fujitsu.com> wrote:
>> > On Thu, 21 Apr 2011 17:10:23 +0900
>> > Minchan Kim <minchan.kim@gmail.com> wrote:
>> >
>> >> Hi Kame,
>> >>
>> >> On Thu, Apr 21, 2011 at 12:43 PM, KAMEZAWA Hiroyuki
>> >> <kamezawa.hiroyu@jp.fujitsu.com> wrote:
>> >> > Ying, please take this just a hint, you don't need to implement this
>> >> > as is.
>> >> > ==
>> >> > Now, memcg-kswapd is created per a cgroup. Considering there are
>> >> > users
>> >> > who creates hundreds on cgroup on a system, it consumes too much
>> >> > resources, memory, cputime.
>> >> >
>> >> > This patch creates a thread pool for memcg-kswapd. All memcg which
>> >> > needs background recalim are linked to a list and memcg-kswapd
>> >> > picks up a memcg from the list and run reclaim. This reclaimes
>> >> > SWAP_CLUSTER_MAX of pages and putback the memcg to the lail of
>> >> > list. memcg-kswapd will visit memcgs in round-robin manner and
>> >> > reduce usages.
>> >> >
>> >>
>> >> I didn't look at code yet but as I just look over the description, I
>> >> have a concern.
>> >> We have discussed LRU separation between global and memcg.
>> >
>> > Please discuss global LRU in other thread. memcg-kswapd is not related
>> > to global LRU _at all_.
>> >
>> > And this patch set is independent from the things we discussed at LSF.
>> >
>> >
>> >> The clear goal is that how to keep _fairness_.
>> >>
>> >> For example,
>> >>
>> >> memcg-1 : # pages of LRU : 64
>> >> memcg-2 : # pages of LRU : 128
>> >> memcg-3 : # pages of LRU : 256
>> >>
>> >> If we have to reclaim 96 pages, memcg-1 would be lost half of pages.
>> >> It's much greater than others so memcg 1's page LRU rotation cycle
>> >> would be very fast, then working set pages in memcg-1 don't have a
>> >> chance to promote.
>> >> Is it fair?
>> >>
>> >> I think we should consider memcg-LRU size as doing round-robin.
>> >>
>> >
>> > This set doesn't implement a feature to handle your example case, at
>> > all.
>>
>> Sure. Sorry for the confusing.
>> I don't mean global LRU but it a fairness although this series is
>> based on per-memcg targeting.
>>
>> >
>> > This patch set handles
>> >
>> > memcg-1: # pages of over watermark : 64
>> > memcg-2: # pages of over watermark : 128
>> > memcg-3: # pages of over watermark : 256
>> >
>> > And finally reclaim all pages over watermarks which user requested.
>> > Considering fairness, what we consider is in what order we reclaim
>> > memory memcg-1, memcg-2, memcg-3 and how to avoid unnecessary cpu
>> > hogging at reclaiming memory all (64+128+256)
>> >
>> > This thread pool reclaim 32 pages per iteration with patch-1 and visit
>> > all
>> > in round-robin.
>> > With patch-2, reclaim 32*weight pages per iteration on each memcg.
>> >
>>
>> I should have seen the patch [2/3] before posting the comment.
>> Maybe you seem consider my concern.
>> Okay. I will look the idea.
>
> For any ideas on global kswapd and soft_limit reclaim based on round-robin (
> discussed in LSF), please move the discussion to :
>
> [RFC no patch yet] memcg: revisit soft_limit reclaim on contention:
>
> http://permalink.gmane.org/gmane.linux.kernel.mm/60966"
>
> I already started with the patch and hopefully to post some result soon.

Okay. I am looking forward to seeing.
Thanks, Ying.

-- 
Kind regards,
Minchan Kim

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      reply	other threads:[~2011-04-22  1:02 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-19  3:57 [PATCH V6 00/10] memcg: per cgroup background reclaim Ying Han
2011-04-19  3:57 ` [PATCH V6 01/10] Add kswapd descriptor Ying Han
2011-04-19  3:57 ` [PATCH V6 02/10] Add per memcg reclaim watermarks Ying Han
2011-04-19  3:57 ` [PATCH V6 03/10] New APIs to adjust per-memcg wmarks Ying Han
2011-04-19  3:57 ` [PATCH V6 04/10] Infrastructure to support per-memcg reclaim Ying Han
2011-04-19  3:57 ` [PATCH V6 05/10] Implement the select_victim_node within memcg Ying Han
2011-04-19  3:57 ` [PATCH V6 06/10] Per-memcg background reclaim Ying Han
2011-04-20  1:03   ` KAMEZAWA Hiroyuki
2011-04-20  3:25     ` Ying Han
2011-04-20  4:20     ` Ying Han
2012-03-19  8:14   ` Zhu Yanhai
2012-03-20  5:37     ` Ying Han
2011-04-19  3:57 ` [PATCH V6 07/10] Add per-memcg zone "unreclaimable" Ying Han
2011-04-19  3:57 ` [PATCH V6 08/10] Enable per-memcg background reclaim Ying Han
2011-04-19  3:57 ` [PATCH V6 09/10] Add API to export per-memcg kswapd pid Ying Han
2011-04-20  1:15   ` KAMEZAWA Hiroyuki
2011-04-20  3:39     ` Ying Han
2011-04-19  3:57 ` [PATCH V6 10/10] Add some per-memcg stats Ying Han
2011-04-21  2:51 ` [PATCH V6 00/10] memcg: per cgroup background reclaim Johannes Weiner
2011-04-21  3:05   ` Ying Han
2011-04-21  3:53     ` Johannes Weiner
2011-04-21  4:00   ` KAMEZAWA Hiroyuki
2011-04-21  4:24     ` Ying Han
2011-04-21  4:46       ` KAMEZAWA Hiroyuki
2011-04-21  5:08     ` Johannes Weiner
2011-04-21  5:28       ` Ying Han
2011-04-23  1:35         ` Johannes Weiner
2011-04-23  2:10           ` Ying Han
2011-04-23  2:34             ` Johannes Weiner
2011-04-23  3:33               ` Ying Han
2011-04-23  3:41                 ` Rik van Riel
2011-04-23  3:49                   ` Ying Han
2011-04-27  7:36                 ` Johannes Weiner
2011-04-27 17:41                   ` Ying Han
2011-04-27 21:37                     ` Johannes Weiner
2011-04-21  5:41       ` KAMEZAWA Hiroyuki
2011-04-21  6:23         ` Ying Han
2011-04-23  2:02         ` Johannes Weiner
2011-04-21  3:40 ` KAMEZAWA Hiroyuki
2011-04-21  3:48   ` [PATCH 2/3] weight for memcg background reclaim (Was " KAMEZAWA Hiroyuki
2011-04-21  6:11     ` Ying Han
2011-04-21  6:38       ` KAMEZAWA Hiroyuki
2011-04-21  6:59         ` Ying Han
2011-04-21  7:01           ` KAMEZAWA Hiroyuki
2011-04-21  7:12             ` Ying Han
2011-04-21  3:50   ` [PATCH 3/3/] fix mem_cgroup_watemark_ok " KAMEZAWA Hiroyuki
2011-04-21  5:29     ` Ying Han
2011-04-21  4:22   ` Ying Han
2011-04-21  4:27     ` KAMEZAWA Hiroyuki
2011-04-21  4:31     ` Ying Han
2011-04-21  3:43 ` [PATCH 1/3] memcg kswapd thread pool (Was " KAMEZAWA Hiroyuki
2011-04-21  7:09   ` Ying Han
2011-04-21  7:14     ` KAMEZAWA Hiroyuki
2011-04-21  8:10   ` Minchan Kim
2011-04-21  8:46     ` KAMEZAWA Hiroyuki
2011-04-21  9:05       ` Minchan Kim
2011-04-21 16:56         ` Ying Han
2011-04-22  1:02           ` Minchan Kim [this message]

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