linux-kernel - Re: [PATCH 3/7 v2] mm: rework __isolate_lru

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Date:	Thu, 15 Mar 2012 10:03:49 +0400
From:	Konstantin Khlebnikov <khlebnikov@...nvz.org>
To:	Hugh Dickins <hughd@...gle.com>
CC:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <jweiner@...hat.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/7 v2] mm: rework __isolate_lru_page() file/anon filter

Hugh Dickins wrote:
> On Sat, 10 Mar 2012, Konstantin Khlebnikov wrote:
>> Konstantin Khlebnikov wrote:
>>>
>>> No, for non-lumpy isolation we don't need this check at all,
>>> because all pages already picked from right lru list.
>>>
>>> I'll send separate patch for this (on top v5 patchset), after meditation =)
>>
>> Heh, looks like we don't need these checks at all:
>> without RECLAIM_MODE_LUMPYRECLAIM we isolate only pages from right lru,
>> with RECLAIM_MODE_LUMPYRECLAIM we isolate pages from all evictable lru.
>> Thus we should check only PageUnevictable() on lumpy reclaim.
>
> Yes, those were great simplfying insights: I'm puzzling over why you
> didn't follow through on them in your otherwise nice 4.5/7, which
> still involves lru bits in the isolate mode?

Actually filter is required for single case: lumpy isolation for shrink_active_list().
Maybe I'm wrong, or this is bug, but I don't see any reasons why this can not happen:
sc->reclaim_mode manipulations are very tricky.

>
> Hugh
>
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