From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id E17BF6B003D for ; Wed, 11 Feb 2009 06:12:10 -0500 (EST) Date: Wed, 11 Feb 2009 03:12:01 -0800 From: Andrew Morton Subject: Re: [PATCH] mm: remove zone->prev_prioriy Message-Id: <20090211031201.cace1c68.akpm@linux-foundation.org> In-Reply-To: <20090211195252.C3BD.KOSAKI.MOTOHIRO@jp.fujitsu.com> References: <28c262360902100257o6a8e2374v42f1ae906c53bcec@mail.gmail.com> <20090210151247.6747f66e.akpm@linux-foundation.org> <20090211195252.C3BD.KOSAKI.MOTOHIRO@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: MinChan Kim , kamezawa.hiroyu@jp.fujitsu.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, riel@redhat.com List-ID: On Wed, 11 Feb 2009 20:06:46 +0900 (JST) KOSAKI Motohiro wrote: > > 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. prev_priority had nothing to do with concurrent reclaim? It was there so that when a task enters direct reclaim against a zone, it will immediately adopt the state which the task which most recently ran direct reclaim had. Without this feature, each time a task enters direct reclaim it will need to "relearn" that state - ramping up, making probably-incorrect decisions as it does so. -- 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/ . Don't email: email@kvack.org