Re: [LSF/MM TOPIC ATTEND]

[Vladimir Davydov <vdavydov@parallels.com>]

On Tue, Jan 06, 2015 at 05:14:35PM +0100, Michal Hocko wrote:
[...]
> And as a memcg co-maintainer I would like to also discuss the following
> topics.
> - We should finally settle down with a set of core knobs exported with
>   the new unified hierarchy cgroups API. I have proposed this already
>   http://marc.info/?l=linux-mm&m=140552160325228&w=2 but there is no
>   clear consensus and the discussion has died later on. I feel it would
>   be more productive to sit together and come up with a reasonable
>   compromise between - let's start from the begining and keep useful and
>   reasonable features.
>   
> - kmem accounting is seeing a lot of activity mainly thanks to Vladimir.
>   He is basically the only active developer in this area. I would be
>   happy if he can attend as well and discuss his future plans in the
>   area. The work overlaps with slab allocators and slab shrinkers so
>   having people familiar with these areas would be more than welcome

One more memcg related topic that is worth discussing IMO:

 - On global memory pressure we walk over all memory cgroups and scan
   pages from each of them. Since there can be hundreds or even
   thousands of memory cgroups, such a walk can be quite expensive,
   especially if the cgroups are small so that to reclaim anything from
   them we have to descend to a lower scan priority. The problem is
   augmented by offline memory cgroups, which now can be dangling for
   indefinitely long time.

   That's why I think we should work out a better algorithm for the
   memory reclaimer. May be, we could rank memory cgroups somehow (by
   their age, memory consumption?) and try to scan only the top ranked
   cgroup during a reclaimer run. This topic is also very close to the
   soft limit reclaim improvements, which Michal has been working on for
   a while.

Thanks,
Vladimir

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