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Date: Fri, 28 Jan 2011 09:20:02 -0600 (CST)
From: Christoph Lameter <cl@linux.com>
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To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
cc: Minchan Kim <minchan.kim@gmail.com>, balbir@linux.vnet.ibm.com,
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        kosaki.motohiro@jp.fujitsu.com
Subject: Re: [PATCH 3/3] Provide control over unmapped pages (v4)
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On Fri, 28 Jan 2011, KAMEZAWA Hiroyuki wrote:

> > > I see it as a tradeoff of when to check? add_to_page_cache or when we
> > > are want more free memory (due to allocation). It is OK to wakeup
> > > kswapd while allocating memory, somehow for this purpose (global page
> > > cache), add_to_page_cache or add_to_page_cache_locked does not seem
> > > the right place to hook into. I'd be open to comments/suggestions
> > > though from others as well.
>
> I don't like add hook here.
> AND I don't want to run kswapd because 'kswapd' has been a sign as
> there are memory shortage. (reusing code is ok.)
>
> How about adding new daemon ? Recently, khugepaged, ksmd works for
> managing memory. Adding one more daemon for special purpose is not
> very bad, I think. Then, you can do
>  - wake up without hook
>  - throttle its work.
>  - balance the whole system rather than zone.
>    I think per-node balance is enough...


I think we already have enough kernel daemons floating around. They are
multiplying in an amazing way. What would be useful is to map all
the memory management background stuff into a process. May call this memd
instead? Perhaps we can fold khugepaged into kswapd as well etc.