Re: [PATCH v2 0/4] memcg: Low-limit reclaim

Roman Gushchin
2014-04-29T10:50:27Z

29.04.2014, 11:42, "Greg Thelen" <gthelen@google.com>:
> On Mon, Apr 28 2014, Roman Gushchin <klamm@yandex-team.ru> wrote:
>
>>  28.04.2014, 16:27, "Michal Hocko" <mhocko@suse.cz>:
>>>  The series is based on top of the current mmotm tree. Once the series
>>>  gets accepted I will post a patch which will mark the soft limit as
>>>  deprecated with a note that it will be eventually dropped. Let me know
>>>  if you would prefer to have such a patch a part of the series.
>>>
>>>  Thoughts?
>>  Looks good to me.
>>
>>  The only question is: are there any ideas how the hierarchy support
>>  will be used in this case in practice?
>>  Will someone set low limit for non-leaf cgroups? Why?
>>
>>  Thanks,
>>  Roman
>
> I imagine that a hosting service may want to give X MB to a top level
> memcg (/a) with sub-jobs (/a/b, /a/c) which may(not) have their own
> low-limits.
>
> Examples:
>
> case_1) only set low limit on /a.  /a/b and /a/c may overcommit /a's
>         memory (b.limit_in_bytes + c.limit_in_bytes > a.limit_in_bytes).
>
> case_2) low limits on all memcg.  But not overcommitting low_limits
>         (b.low_limit_in_in_bytes + c.low_limit_in_in_bytes <=
>         a.low_limit_in_in_bytes).

Thanks!

With use_hierarchy turned on it looks perfectly usable.