linux-kernel - Re: [PATCH] mm: stop kswapd's infinite loop at high order allocation take2

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Message-ID: <28c262360901020229k55d47445yc9a6c9c7aa3e9c66@mail.gmail.com>
Date:	Fri, 2 Jan 2009 19:29:16 +0900
From:	"MinChan Kim" <minchan.kim@...il.com>
To:	"KOSAKI Motohiro" <kosaki.motohiro@...fujitsu.com>
Cc:	"Mel Gorman" <mel@....ul.ie>, LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Nick Piggin" <npiggin@...e.de>,
	"wassim dagash" <wassim.dagash@...il.com>
Subject: Re: [PATCH] mm: stop kswapd's infinite loop at high order allocation take2

On Fri, Jan 2, 2009 at 7:00 PM, KOSAKI Motohiro
<kosaki.motohiro@...fujitsu.com> wrote:
>> 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 :)

Hm. I read Nick's explain.
I understand his point.

Nick said,
"A higher kswapd reclaim order shouldn't weaken kswapd
postcondition for order-0 memory."

My patch don't prevent order-0 memory reclaim. After all, it will do it.
It also can do best effort to reclaim other order size.

In this case, others order size reclaim is needless  ?


-- 
Kinds regards,
MinChan Kim
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