linux-kernel - Re: [RFC] cgroup TODOs

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: <5056E1FC.1090508@parallels.com>
Date:	Mon, 17 Sep 2012 12:40:28 +0400
From:	Glauber Costa <glommer@...allels.com>
To:	Tejun Heo <tj@...nel.org>
CC:	Vivek Goyal <vgoyal@...hat.com>,
	<containers@...ts.linux-foundation.org>, <cgroups@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Li Zefan <lizefan@...wei.com>,
	Michal Hocko <mhocko@...e.cz>,
	Peter Zijlstra <peterz@...radead.org>,
	Paul Turner <pjt@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Thomas Graf <tgraf@...g.ch>, Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Neil Horman <nhorman@...driver.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Serge Hallyn <serge.hallyn@...ntu.com>
Subject: Re: [RFC] cgroup TODOs

On 09/15/2012 12:39 AM, Tejun Heo wrote:
> Hello, again.
> 
> On Fri, Sep 14, 2012 at 12:49:50PM -0700, Tejun Heo wrote:
>> That said, if someone can think of a better solution, I'm all ears.
>> One thing that *has* to be maintained is that it should be able to tag
>> a resource in such way that its associated controllers are
>> identifiable regardless of which task is looking at it.
> 
> So, I thought about it more.  How about we do "consider / ignore this
> node" instead of "(don't) nest beyond this level".  For example, let's
> assume a tree like the following.
> 
>         R
>      /  |  \
>     A   B   C
>    / \
>   AA AB
> 
> If we want to differentiate between AA and AB, we'll have to consider
> the whole tree with the previous sheme - A needs to nest, so R needs
> to nest and we end up with the whole tree.  Instead, if we have honor
> / ignore this node.  We can set the honor bit on A, AA and AB and see
> the tree as
> 
>         R
>      /
>     A
>    / \
>   AA AB
> 
> We still see the intermediate A node but can ignore the other
> branches.  Implementation and concept-wise, it's fairly simple too.
> For any given node and controller, you travel upwards until you meet a
> node which has the controller enabled and that's the cgroup the
> controller considers.
> 
> Thanks.
> 

That is exactly what I proposed in our previous discussions around
memcg, with files like "available_controllers" , "current_controllers".
Name chosen to match what other subsystems already do.

if memcg is not in "available_controllers" for a node, it cannot be seen
by anyone bellow that level.


--
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/