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Message-ID: <2f11576a0901020200t3a6dadf5qa944432cd9fd8873@mail.gmail.com>
Date: Fri, 2 Jan 2009 19:00:41 +0900
From: "KOSAKI Motohiro" <kosaki.motohiro@jp.fujitsu.com>
To: "MinChan Kim" <minchan.kim@gmail.com>
Subject: Re: [PATCH] mm: stop kswapd's infinite loop at high order allocation take2
Cc: "Mel Gorman" <mel@csn.ul.ie>, LKML <linux-kernel@vger.kernel.org>,
       linux-mm <linux-mm@kvack.org>,
       "Andrew Morton" <akpm@linux-foundation.org>,
       "Nick Piggin" <npiggin@suse.de>,
       "wassim dagash" <wassim.dagash@gmail.com>
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References: <20081231115332.GB20534@csn.ul.ie>
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	 <20090101021240.A057.KOSAKI.MOTOHIRO@jp.fujitsu.com>
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> Hi, kosaki-san.
>
> I read the previous threads now. It's rather late :(.
>
> I think it's rather awkward that sudden big change of order from 10 to 0.
>
> This problem causes zone_water_mark's fail.
> It mean now this zone's proportional free page per order size is not good.
> Although order-0 page is very important, Shouldn't we consider other
> order allocations ?
>
> So I want to balance zone's proportional free page.
> How about following ?
>
> if (nr_reclaimed < SWAP_CLUSTER_MAX) {
>   if (order != 0) {
>     order -=1;
>     sc.order -=1;
>   }
> }
>
> It prevents infinite loop and do best effort to make zone's
> proportional free page per order size good.
>
> It's just my opinion within my knowledge.
> If it have a problem, pz, explain me :)

Please read Nick's expalin. it explain very kindly :)