From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 09 Feb 2006 16:22:40 +0900 From: IWAMOTO Toshihiro Subject: Re: [PATCH 6/9] clockpro-clockpro.patch In-Reply-To: <1139428810.4668.20.camel@localhost.localdomain> References: <20051230223952.765.21096.sendpatchset@twins.localnet> <20051230224312.765.58575.sendpatchset@twins.localnet> <20051231002417.GA4913@dmt.cnet> <1136028546.17853.69.camel@twins> <20060105094722.897C574030@sv1.valinux.co.jp> <20060106090135.3525D74031@sv1.valinux.co.jp> <20060124063010.B85C77402D@sv1.valinux.co.jp> <20060124072503.BAF6A7402F@sv1.valinux.co.jp> <1138958705.5450.9.camel@localhost.localdomain> <20060208100505.247D874034@sv1.valinux.co.jp> <1139428810.4668.20.camel@localhost.localdomain> MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Message-Id: <20060209072240.351A174031@sv1.valinux.co.jp> Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: IWAMOTO Toshihiro , Rik van Riel , Peter Zijlstra , Marcelo Tosatti , linux-mm@kvack.org, Andrew Morton , Christoph Lameter , Wu Fengguang , Nick Piggin , Marijn Meijles List-ID: At Wed, 08 Feb 2006 21:00:10 +0100, Peter Zijlstra wrote: > > On Wed, 2006-02-08 at 19:05 +0900, IWAMOTO Toshihiro wrote: > > I've noticed the way page_replace_reinsert puts pages to a list is > > different from what the paper (TR-05-3.pdf) says. > > I reread the paper, and you seem to have found a detail I had not > noticed before. Thanks! > > It concerns section 4.3 paragraph 2 and the use of list head as defined > in section 4.2 paragraph 2. > > The way I read it is that pages that have their reference bit set are > moved to the list head, which according to 4.2.2 is the page right in > front of hand hot (which would correspond to the tail of the HAND_HOT > list). > > So I agree the current code is wrong. However I read it differently. > > In your patch you move all Hot pages to the head of the hot list, which > effectively leaves them in place. The other pages are moved to the head > of the cold list, which is right behind hand hot. > > So I don't see your condition nor the placement. Could you explain your > reasoning? My patch should be okay for pages which are already hot when Hcold passes, but I found that the paper says pages which are turned hot by Hcold should be placed at the list head, which requires a page flag to implement. I think the PG_test bit could be abused for this purpose. > > I wonder if this divergence is intended or not, but the attached patch > > gave a major improvement. The paper doesn't have cold to cold test page state transition, although Song said otherwise in the mailing list. I thought this reinsert behavior is a part of the divergence. -- IWAMOTO Toshihiro -- 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