[Devel] Re: [PATCH 08/10] memcg: Add CONFIG_CGROUP_MEM_RES_CTLR_KMEM_ACCT_ROOT.

[KAMEZAWA Hiroyuki]

On Tue, 28 Feb 2012 15:36:27 -0800
Suleiman Souhlal <suleiman at google.com> wrote:

> On Tue, Feb 28, 2012 at 5:34 AM, Glauber Costa <glommer at parallels.com> wrote:
> > On 02/27/2012 07:58 PM, Suleiman Souhlal wrote:
> >>
> >> This config option dictates whether or not kernel memory in the
> >> root cgroup should be accounted.
> >>
> >> This may be useful in an environment where everything is supposed to be
> >> in a cgroup and accounted for. Large amounts of kernel memory in the
> >> root cgroup would indicate problems with memory isolation or accounting.
> >
> >
> > I don't like accounting this stuff to the root memory cgroup. This causes
> > overhead for everybody, including people who couldn't care less about memcg.
> >
> > If it were up to me, we would simply not account it, and end of story.
> >
> > However, if this is terribly important for you, I think you need to at
> > least make it possible to enable it at runtime, and default it to disabled.
> 
> Yes, that is why I made it a config option. If the config option is
> disabled, that memory does not get accounted at all.
> 
> Making it configurable at runtime is not ideal, because we would
> prefer slab memory that was allocated before cgroups are created to
> still be counted toward root.
> 

I never like to do accounting in root cgroup.
If you want to do this, add config option to account _all_ memory in the root.
Accounting only slab seems very dirty hack.

Thanks,
-Kame