linux-kernel - Re: [patch v3 -mm 1/3] memcg: integrate soft reclaim tighter with zone shrinking code

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: <b4e0e499-b922-4e9c-a0f8-02318ddf3b9b@email.android.com>
Date:	Fri, 17 May 2013 13:27:09 -0400
From:	Johannes Weiner <hannes@...xchg.org>
To:	Tejun Heo <tj@...nel.org>
CC:	Michal Hocko <mhocko@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Ying Han <yinghan@...gle.com>, Hugh Dickins <hughd@...gle.com>,
	Glauber Costa <glommer@...allels.com>,
	Michel Lespinasse <walken@...gle.com>,
	Greg Thelen <gthelen@...gle.com>,
	Balbir Singh <bsingharora@...il.com>
Subject: Re: [patch v3 -mm 1/3] memcg: integrate soft reclaim tighter with zone shrinking code



Tejun Heo <tj@...nel.org> wrote:

>Hello, Johannes.
>
>On Fri, May 17, 2013 at 12:02:47PM -0400, Johannes Weiner wrote:
>> There are setups with thousands of groups that do not even use soft
>> limits.  Having them pointlessly iterate over all of them for every
>> couple of pages reclaimed is just not acceptable.
>
>Hmmm... if the iteration is the problem, it shouldn't be difficult to
>build list of children which should be iterated.  Would that make it
>acceptable?

You mean, a separate structure that tracks which groups are in excess of the limit?  Like the current tree? :)

Kidding aside, yes, that would be better, and an unsorted list would probably be enough for the global case.

To support target reclaim soft limits later on, we could maybe propagate tags upwards the cgroup tree when a group is in excess so that reclaim can be smarter about which subtrees to test for soft limits and which to skip during the soft limit pass.  The no-softlimit-set-anywhere case is then only a single tag test in the root cgroup.

But starting with the list would be simple enough, delete a bunch of code, come with the same performance improvements etc.
-- 
Sent from my Android phone with K-9 Mail. Please excuse my brevity.
--
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/