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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prev parent 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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