linux-kernel - Re: [PATCH 01/10] mm: vmscan: Limit the number of pages kswapd reclaims at each priority

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Date:	Fri, 05 Apr 2013 08:05:28 +0800
From:	Will Huck <will.huckk@...il.com>
To:	Rik van Riel <riel@...hat.com>
CC:	Johannes Weiner <hannes@...xchg.org>, Mel Gorman <mgorman@...e.de>,
	Linux-MM <linux-mm@...ck.org>, Jiri Slaby <jslaby@...e.cz>,
	Valdis Kletnieks <Valdis.Kletnieks@...edu>,
	Zlatko Calusic <zcalusic@...sync.net>,
	dormando <dormando@...ia.net>,
	Satoru Moriya <satoru.moriya@....com>,
	Michal Hocko <mhocko@...e.cz>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 01/10] mm: vmscan: Limit the number of pages kswapd reclaims
 at each priority

Hi Rik,
On 03/22/2013 09:01 PM, Rik van Riel wrote:
> On 03/22/2013 12:59 AM, Will Huck wrote:
>> Hi Rik,
>> On 03/22/2013 11:56 AM, Will Huck wrote:
>>> Hi Rik,
>>> On 03/22/2013 11:52 AM, Rik van Riel wrote:
>>>> On 03/21/2013 08:05 PM, Will Huck wrote:
>>>>
>>>>> One offline question, how to understand this in function 
>>>>> balance_pgdat:
>>>>> /*
>>>>>   * Do some background aging of the anon list, to give
>>>>>   * pages a chance to be referenced before reclaiming.
>>>>>   */
>>>>> age_acitve_anon(zone, &sc);
>>>>
>>>> The anon lrus use a two-handed clock algorithm. New anonymous pages
>>>> start off on the active anon list. Older anonymous pages get moved
>>>> to the inactive anon list.
>>>
>>> The file lrus also use the two-handed clock algorithm, correct?
>>
>> After reinvestigate the codes, the answer is no. But why have this
>> difference? I think you are the expert for this question, expect your
>> explanation. :-)
>
> Anonymous memory has a smaller amount of memory (on the order
> of system memory), most of which is or has been in a working
> set at some point.
>
> File system cache tends to have two distinct sets. One part
> are the frequently accessed files, another part are the files
> that are accessed just once or twice.
>
> The file working set needs to be protected from streaming
> IO. We do this by having new file pages start out on the

Is there streaming IO workload or benchmark?

> inactive file list, and only promoted to the active file
> list if they get accessed twice.
>
>

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