Re: [PATCH 1/7] memcg: add high/low watermark to res_counter

On Mon, 9 May 2011 14:49:17 +0200
Michal Hocko [off-list ref] wrote:

On Mon 09-05-11 12:18:17, Johannes Weiner wrote:

quoted

On Mon, May 09, 2011 at 04:10:47PM +0900, KAMEZAWA Hiroyuki wrote:

[...]

quoted

What I am wondering, though: we already have a limit to push back
memcgs when we need memory, the soft limit.  The 'need for memory' is
currently defined as global memory pressure, which we know may be too
late.  The problem is not having no limit, the problem is that we want
to control the time of when this limit is enforced.  So instead of
adding another limit, could we instead add a knob like

	memory.force_async_soft_reclaim

that asynchroneously pushes back to the soft limit instead of having
another, separate limit to configure?

Hmm, ok to me. 

Sound much better than a separate watermark to me. I am just wondering
how we would implement soft unlimited groups with background reclaim.
Btw. is anybody relying on such configuration? To me it sounds like
something should be either limited or unlimited and making it half of
both is hacky.

I don't think of soft-unlimited configuration. I don't want to handle it
in some automatic way.

Anyway, I'll add
  - _automatic_ background reclaim against the limit of memory, which works
    regarless of softlimit.
  - An interface for force softlimit.

Thanks,
-Kame

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