linux-kernel - Re: RFC: Easy-Reclaimable LRU list

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Message-ID: <4FE549E8.2050905@jp.fujitsu.com>
Date:	Sat, 23 Jun 2012 13:45:28 +0900
From:	Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Minchan Kim <minchan@...nel.org>
CC:	John Stultz <john.stultz@...aro.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Anton Vorontsov <anton.vorontsov@...aro.org>,
	Pekka Enberg <penberg@...nel.org>,
	Wu Fengguang <fengguang.wu@...el.com>,
	Hugh Dickins <hughd@...gle.com>
Subject: Re: RFC:  Easy-Reclaimable LRU list

(2012/06/22 15:57), Minchan Kim wrote:
> Hi John,
>
> On 06/22/2012 04:21 AM, John Stultz wrote:
>
>> On 06/18/2012 10:49 PM, Minchan Kim wrote:
>>> Hi everybody!
>>>
>>> Recently, there are some efforts to handle system memory pressure.
>>>
>>> 1) low memory notification - [1]
>>> 2) fallocate(VOLATILE) - [2]
>>> 3) fadvise(NOREUSE) - [3]
>>>
>>> For them, I would like to add new LRU list, aka "Ereclaimable" which
>>> is opposite of "unevictable".
>>> Reclaimable LRU list includes _easy_ reclaimable pages.
>>> For example, easy reclaimable pages are following as.
>>>
>>> 1. invalidated but remained LRU list.
>>> 2. pageout pages for reclaim(PG_reclaim pages)
>>> 3. fadvise(NOREUSE)
>>> 4. fallocate(VOLATILE)
>>>
>>> Their pages shouldn't stir normal LRU list and compaction might not
>>> migrate them, even.
>>> Reclaimer can reclaim Ereclaimable pages before normal lru list and
>>> will avoid unnecessary
>>> swapout in anon pages in easy-reclaimable LRU list.
>>
>> I was hoping there would be further comment on this by more core VM
>> devs, but so far things have been quiet (is everyone on vacation?).
>
>
> At least, there are no dissent comment until now.
> Let be a positive. :)

I think this is interesting approach. Major concern is how to guarantee EReclaimable
pages are really EReclaimable...Do you have any idea ? madviced pages are really
EReclaimable ?

A (very) small concern is will you use one more page-flags for this ? ;)

Thanks,
-Kame





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