linux-kernel - Re: [RFC][PATCH] prevent incorrect oom under split

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Message-ID: <28c262360806252137j78a90480n6c3973cd489c1ef2@mail.gmail.com>
Date:	Thu, 26 Jun 2008 13:37:29 +0900
From:	"MinChan Kim" <minchan.kim@...il.com>
To:	"Takenori Nagano" <t-nagano@...jp.nec.com>
Cc:	"Peter Zijlstra" <peterz@...radead.org>,
	"KOSAKI Motohiro" <kosaki.motohiro@...fujitsu.com>,
	"Rik van Riel" <riel@...hat.com>, linux-mm <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Lee Schermerhorn" <Lee.Schermerhorn@...com>,
	akpm@...ux-foundation.org
Subject: Re: [RFC][PATCH] prevent incorrect oom under split_lru

On Thu, Jun 26, 2008 at 10:49 AM, Takenori Nagano
<t-nagano@...jp.nec.com> wrote:
> MinChan Kim wrote:
>> Hi peter,
>>
>> I agree with you.  but if application's virtual address space is big,
>> we have a hard problem with mlockall since memory pressure might be a
>> big.
>> Of course, It will be a RT application design problem.
>>
>>> The much more important case is desktop usage - that is where we run non
>>> real-time code, but do expect 'low' latency due to user-interaction.
>>>
>>> >From hitting swap on my 512M laptop (rather frequent occurance) I know
>>> we can do better here,..
>>>
>>
>> Absolutely. It is another example. So, I suggest following patch.
>> It's based on idea of Takenori Nagano's memory reclaim more efficiently.
>
> Hi Kim-san,
>
> Thank you for agreeing with me.
>
> I have one question.
> My patch don't mind priority. Why do you need "priority == 0"?

Hi, Takenori-san.

Now, Kosaiki-san's patch didn't consider application latency.
That patch scan all lru[x] pages when memory pressure is very high.
(ie, priority == 0)
It will cause application latency to high as peter and me notice that.
We need a idea which prevent big scanning overhead
I modified your idea to prevent big scanning overhead only when memory
pressure is very big.


> Thanks,
>  Takenori
>



-- 
Kinds regards,
MinChan Kim
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