linux-kernel - Re: [RFC 0/4] memcg: Low-limit reclaim

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140129182259.GA6711@dhcp22.suse.cz>
Date:	Wed, 29 Jan 2014 19:22:59 +0100
From:	Michal Hocko <mhocko@...e.cz>
To:	Roman Gushchin <klamm@...dex-team.ru>
Cc:	linux-mm@...ck.org, Johannes Weiner <hannes@...xchg.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Ying Han <yinghan@...gle.com>, Hugh Dickins <hughd@...gle.com>,
	Michel Lespinasse <walken@...gle.com>,
	Greg Thelen <gthelen@...gle.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Tejun Heo <tj@...nel.org>
Subject: Re: [RFC 0/4] memcg: Low-limit reclaim

On Fri 24-01-14 15:07:02, Roman Gushchin wrote:
> Hi, Michal!

Hi,

> As you can remember, I've proposed to introduce low limits about a year ago.
> 
> We had a small discussion at that time: http://marc.info/?t=136195226600004 .

yes I remember that discussion and vaguely remember the proposed
approach. I really wanted to prevent from introduction of a new knob but
things evolved differently than I planned since then and it turned out
that the knew knob is unavoidable. That's why I came with this approach
which is quite different from yours AFAIR.
 
> Since that time we intensively use low limits in our production
> (on thousands of machines). So, I'm very interested to merge this
> functionality into upstream.

Have you tried to use this implementation? Would this work as well?
My very vague recollection of your patch is that it didn't cover both
global and target reclaims and it didn't fit into the reclaim very
naturally it used its own scaling method. I will have to refresh my
memory though.

> In my experience, low limits also require some changes in memcg page accounting
> policy. For instance, an application in protected cgroup should have a guarantee
> that it's filecache belongs to it's cgroup and is protected by low limit
> therefore. If the filecache was created by another application in other cgroup,
> it can be not so. I've solved this problem by implementing optional page
> reaccouting on pagefaults and read/writes.

Memory sharing is a separate issue and we should discuss that
separately. 

> I can prepare my current version of patchset, if someone is interested.

Sure, having something to compare with is always valuable.

> Regards,
> Roman
-- 
Michal Hocko
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/