Re: [PATCH 4/4] Memory controller soft limit reclaim on contention (v5)

[Balbir Singh <balbir@linux.vnet.ibm.com>]

* KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> [2009-03-13 13:50:26]:

> > > > I have two objection to this.
> > > > 
> > > > - "if (!order || !did_some_progress)" mean no call try_to_free_pages()
> > > >   in order>0 and did_some_progress>0 case.
> > > >   but mem_cgroup_soft_limit_reclaim() don't have lumpy reclaim.
> > > >   then, it break high order reclaim.
> > > 
> > > I am sending a fix for this right away. Thanks, the check should be
> > > if (order || !did_some_progress)
> > 
> > No.
> > 
> > it isn't enough.
> > after is does, order-1 allocation case twrice reclaim (soft limit shrinking
> > and normal try_to_free_pages()).
> > then, order-1 reclaim makes slower about 2 times.
> > 
> > unfortunately, order-1 allocation is very frequent. it is used for
> > kernel stack.
> 
> in normal order-1 reclaim is:
> 
> 1. try_to_free_pages()
> 2. get_page_from_freelist()
> 3. retry if order-1 page don't exist
> 
> Coundn't you use the same logic?

Sorry, forgot to answer this question earlier.

I assume that by order-1 you mean 2 pages (2^1).

Are you suggesting that if soft limit reclaim fails, we retry? Not
sure if I understand your suggestion completely.


-- 
	Balbir

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