From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 415FF6B0169 for ; Mon, 8 Aug 2011 18:30:51 -0400 (EDT) Received: by qyk7 with SMTP id 7so3155213qyk.14 for ; Mon, 08 Aug 2011 15:30:48 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20110808122255.GC14803@tiehlicka.suse.cz> References: <20110727111002.9985.94938.stgit@localhost6> <20110808110207.30777.30800.stgit@localhost6> <20110808122255.GC14803@tiehlicka.suse.cz> Date: Tue, 9 Aug 2011 07:30:48 +0900 Message-ID: Subject: Re: [PATCH v2] vmscan: reverse lru scanning order From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Konstantin Khlebnikov , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , KAMEZAWA Hiroyuki , Rik van Riel , KOSAKI Motohiro On Mon, Aug 8, 2011 at 9:22 PM, Michal Hocko 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org