Re: [RFC] cgroup TODOs

From: Tejun Heo
Date: Thu Sep 20 2012 - 14:26:56 EST


Hello,

On Wed, Sep 19, 2012 at 06:33:15PM -0700, Andy Lutomirski wrote:
> [grr. why does gmane scramble addresses?]

You can append /raw to the message url and see the raw mssage.

http://article.gmane.org/gmane.linux.kernel.containers/23802/raw

> > I think this level of flexibility should be enough for most use
> > cases. If someone disagrees, please voice your objections now.
>
> OK, I'll bite.
>
> I have a server that has a whole bunch of cores. A small fraction of
> those cores are general purpose and run whatever they like. The rest
> are tightly controlled.
>
> For simplicity, we have two cpusets that we use. The root allows all
> cpus. The other one only allows the general purpose cpus. We shove
> everything into the general-purpose-only cpuset, and then we move
> special stuff back to root. (We also shove some kernel threads into a
> non-root cpuset using the 'cset' tool.)

Using root for special stuff probably isn't a good idea and moving
bound kthreads into !root cgroups is already disallowed.

> Enter systemd, which wants a hierarchy corresponding to services. If we
> were to use it, we might end up violating its hierarchy.
>
> Alternatively, if we started using memcg, then we might have some tasks
> to have more restrictive memory usage but less restrictive cpu usage.
>
> As long as we can still pull this off, I'm happy.

IIUC, you basically want just two groups w/ cpuset and use it for
loose cpu ioslation for high priority jobs. Structure-wise, I don't
think it's gonna be a problem although using root for special stuff
would need to change.

Thanks.

--
tejun
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