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Message-ID: <2f11576a0806090638u445209e7m359c03a4776826be@mail.gmail.com>
Date: Mon, 9 Jun 2008 22:38:19 +0900
From: "KOSAKI Motohiro" <kosaki.motohiro@jp.fujitsu.com>
To: "MinChan Kim" <minchan.kim@gmail.com>
Subject: Re: [PATCH -mm 04/25] free swap space on swap-in/activation
Cc: "Rik van Riel" <riel@redhat.com>,
       "Andrew Morton" <akpm@linux-foundation.org>,
       linux-kernel@vger.kernel.org, lee.schermerhorn@hp.com,
       "Hugh Dickins" <hugh@veritas.com>
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Hi Kim-san,

>> - Can completely optimise the thing away if !CONFIG_SWAP.
>
> I think we can optimize more and more in case of if !CONFIG_SWAP.
> If system are !CONFIG_SWAP, we can never  swap out anonymous pages.
>
> Don't we manage anonymous pages with list ?
>
> Such system don't need to insert anonymous pages into lru list when fault occur.
> It is just needless overhead.
>
> Also, If we can't reclaim anonymous pages, don't we need anon rmap facility ?
> I don't know well which subsystems used rmap.
>
> If pageout only use anonymous rmap for pageout,
> we can remove anonymous rmapping code in case of !CONFIG_SWAP

You are right.
but I think rmap isn't bottle neck in embedded system.
Why do you want remove that?