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]

Date:	Mon, 17 Sep 2012 09:40:02 -0700
From:	Tejun Heo <tj@...nel.org>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	containers@...ts.linux-foundation.org, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org, Li Zefan <lizefan@...wei.com>,
	Michal Hocko <mhocko@...e.cz>,
	Glauber Costa <glommer@...allels.com>,
	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

Hello,

On Mon, Sep 17, 2012 at 11:05:18AM -0400, Vivek Goyal wrote:
> As a developer, I will be happy to support only one model and keep code
> simple. I am only concerned that for blkcg we have still not charted
> out a clear migration path. The warning message your patch is giving
> out will work only if we decide to not treat task and groups at same
> level.

It may not be enough but it still is in the right direction.

> > Another problem is that configuration isn't contained in cgroup
> > proper.  We need a way to assign weights to individual tasks which can
> > be somehow directly compared against group weights.  cpu cooks
> > priority for this and blkcg may be able to cook ioprio but it's nasty
> > and unobvious.  Also, let's say we grow network bandwidth controller
> > for whatever reason.  What value are we gonna use?
> 
> So if somebody cares about settting SO_PRIORITY for traffic originating
> from a tasks, move it into a cgroup. Otherwise they all get default
> priority.

I don't know.  Do we wanna add, say, prctl for memory weight too?

> So to me, leaving this decision to userspace based on their requirement
> makes sense.

Leaving too many decisions to userland is one of the reasons that got
us into this mess, so I'm not sold on flexibility for flexibility's
sake.

> Yes, creating a hidden group for tasks in current group should not be
> hard from implementation point of view. But again, I am concerned about
> configuration of hidden group and I also don't like the idea of taking
> flexibility away from user to treat tasks and group at same level.

I don't know.  Create a reserved directory for it?  I do like the idea
of taking flexibility away form user unless it's actually useful but
am a bit worried we might be too late for that. :(

Thanks.

-- 
tejun
--
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/