From: Minchan Kim <minchan.kim@gmail.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Rik van Riel <riel@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [PATCH v2] vmscan: reverse lru scanning order
Date: Tue, 9 Aug 2011 07:30:48 +0900 [thread overview]
Message-ID: <CAEwNFnD4GH0nr+7ngPBj2uG4jnKb20g3_wLO6HyvHj+vzt+Jzg@mail.gmail.com> (raw)
In-Reply-To: <20110808122255.GC14803@tiehlicka.suse.cz>
On Mon, Aug 8, 2011 at 9:22 PM, Michal Hocko <mhocko@suse.cz> wrote:
> On Mon 08-08-11 15:02:07, Konstantin Khlebnikov wrote:
>> LRU scanning order was accidentially changed in commit v2.6.27-5584-gb69408e:
>> "vmscan: Use an indexed array for LRU variables".
>> Before that commit reclaimer always scan active lists first.
>>
>> This patch just reverse it back.
>
> I am still not sure I see why the ordering matters that much.
> One thing that might matter is that shrink_list moves some pages from
> active to inactive list if inactive is low so it makes sense to try to
> shrink active before inactive. It would be a problem if inactive was
> almost empty. Then we would just waste time by shrinking inactive first.
> I am not sure how real problem is that, though.
>
> Whatever is the reason, I think it should be documented in the
> changelog.
> The change makes sense to me.
>
Absolutely agree with Michal.
I think the patch itself doesn't have a problem and even it is does make sense.
But we need changelog why we need it.
I don't want to overwrite recent git log without any issue.
It annoys us when we find a bug by git-blame. ;-)
--
Kind regards,
Minchan Kim
next prev parent reply other threads:[~2011-08-08 22:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-27 11:10 [PATCH RFC] mm: reverse lru scanning order Konstantin Khlebnikov
2011-08-01 16:15 ` Konstantin Khlebnikov
2011-08-01 23:45 ` KOSAKI Motohiro
2011-08-08 11:02 ` [PATCH v2] vmscan: " Konstantin Khlebnikov
2011-08-08 12:22 ` Michal Hocko
2011-08-08 22:30 ` Minchan Kim [this message]
2011-08-08 23:48 ` KAMEZAWA Hiroyuki
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