From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH] Update Unevictable LRU and Mlocked Pages documentation From: Lee Schermerhorn In-Reply-To: <48931AD1.6040904@linux-foundation.org> References: <1217452439.7676.26.camel@lts-notebook> <4891C8BC.1020509@linux-foundation.org> <1217515429.6507.7.camel@lts-notebook> <489313AC.3080605@linux-foundation.org> <20080801100623.4aae3e37@bree.surriel.com> <48931AD1.6040904@linux-foundation.org> Content-Type: text/plain Date: Fri, 01 Aug 2008 10:36:08 -0400 Message-Id: <1217601369.6232.16.camel@lts-notebook> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Rik van Riel , Andrew Morton , linux-mm , KOSAKI Motohiro , Kamezawa Hiroyuki , Nick Piggin List-ID: On Fri, 2008-08-01 at 09:16 -0500, Christoph Lameter wrote: > Rik van Riel wrote: > > On Fri, 01 Aug 2008 08:46:20 -0500 > > Christoph Lameter wrote: > > > >> Yes I know and I think the rationale is not convincing if the justification > >> of the additional LRU is primarily for page migration. > > > > Basically there are two alternatives: > > I think we have sufficient reasons to have a second LRU (see my earlier mail) > just the text did not emphasize the right ones. Really? You think it would be OK to leave maybe gigabytes of mlocked pages non-migratable? This would prevent defrag, hotplug, and cpuset movement. Since you went to the effort to make mlocked pages migratable in the first place, I thought we ought to preserve this capability. This was MY primary reason for keeping them on an LRU-like list that isolate_lru_page and the new putback_lru_page() know about. Otherwise, we could just let them float, unmanaged, as Nick's original patch did. I wanted to capture this in the doc so that down the road, folks will at least think about this implication when considering leaving pages unmanaged by any "lru list". The rationale that Rik mentioned--common handling, as much as possible--was the second reason mentioned in the text. Perhaps my wording could use some rework/clarification. Lee -- 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