From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755823AbZBKLHA (ORCPT ); Wed, 11 Feb 2009 06:07:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752994AbZBKLGu (ORCPT ); Wed, 11 Feb 2009 06:06:50 -0500 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:36166 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751156AbZBKLGt (ORCPT ); Wed, 11 Feb 2009 06:06:49 -0500 From: KOSAKI Motohiro To: Andrew Morton Subject: Re: [PATCH] mm: remove zone->prev_prioriy Cc: kosaki.motohiro@jp.fujitsu.com, MinChan Kim , kamezawa.hiroyu@jp.fujitsu.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, riel@redhat.com In-Reply-To: <20090210151247.6747f66e.akpm@linux-foundation.org> References: <28c262360902100257o6a8e2374v42f1ae906c53bcec@mail.gmail.com> <20090210151247.6747f66e.akpm@linux-foundation.org> Message-Id: <20090211195252.C3BD.KOSAKI.MOTOHIRO@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.42 [ja] Date: Wed, 11 Feb 2009 20:06:46 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Tue, 10 Feb 2009 19:57:01 +0900 > MinChan Kim wrote: > > > As you know, prev_priority is used as a measure of how much stress page reclaim. > > But now we doesn't need it due to split-lru's way. > > > > I think it would be better to remain why prev_priority isn't needed any more > > and how split-lru can replace prev_priority's role in changelog. > > > > In future, it help mm newbies understand change history, I think. > > Yes, I'd be fascinated to see that explanation. > > In http://groups.google.pn/group/linux.kernel/browse_thread/thread/fea9c9a0b43162a1 > it was asserted that we intend to use prev_priority again in the future. > > We discussed this back in November: > http://lkml.indiana.edu/hypermail/linux/kernel/0811.2/index.html#00001 > > And I think that I still think that the VM got worse due to its (new) > failure to track previous state. IIRC, the response to that concern > was quite similar to handwavy waffling. Yes. I still think it's valuable code. I think, In theory, VM sould take parallel reclaim bonus. However, recently, KAMEZAWA-san reported memcg prev_priority code are busted due to hierarchical-memory-reclaim and he dislike maintain unused function. http://marc.info/?l=linux-mm&m=123258289017433&w=2 and, at that time I can't show good example workload of parallel reclaim bonus effective. Therefore I agreed to drop this and insert it again at re-using time ;-)