From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755897Ab2KUTjP (ORCPT ); Wed, 21 Nov 2012 14:39:15 -0500 Received: from cantor2.suse.de ([195.135.220.15]:44158 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755748Ab2KUTjN (ORCPT ); Wed, 21 Nov 2012 14:39:13 -0500 Date: Wed, 21 Nov 2012 19:39:08 +0000 From: Mel Gorman To: Ingo Molnar Cc: Peter Zijlstra , Andrea Arcangeli , Rik van Riel , Johannes Weiner , Hugh Dickins , Thomas Gleixner , Paul Turner , Lee Schermerhorn , Alex Shi , Linus Torvalds , Andrew Morton , Linux-MM , LKML Subject: Re: [PATCH 36/46] mm: numa: Use a two-stage filter to restrict pages being migrated for unlikely task<->node relationships Message-ID: <20121121193908.GN8218@suse.de> References: <1353493312-8069-1-git-send-email-mgorman@suse.de> <1353493312-8069-37-git-send-email-mgorman@suse.de> <20121121182537.GB29893@gmail.com> <20121121191547.GM8218@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20121121191547.GM8218@suse.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 21, 2012 at 07:15:47PM +0000, Mel Gorman wrote: > I've added a note now to that effect now. For all the patches with notes > or any other ones, I'll be very happy to add the Signed-offs back on if > the original authors acknowledge they are ok with the end result. If you > recall, in the original V1 of this series I said; > > This series steals very heavily from both autonuma and schednuma > with very little original code. In some cases I removed the > signed-off-bys because the result was too different. I have noted > in the changelog where this happened but the signed-offs can be > restored if the original authors agree. > > Just to compare, this is the wording in "autonuma: memory follows CPU > algorithm and task/mm_autonuma stats collection" > > +/* > + * In this function we build a temporal CPU_node<->page relation by > + * using a two-stage autonuma_last_nid filter to remove short/unlikely > + * relations. > + * > + * Using P(p) ~ n_p / n_t as per frequentest probability, we can > + * equate a node's CPU usage of a particular page (n_p) per total > + * usage of this page (n_t) (in a given time-span) to a probability. > + * > + * Our periodic faults will then sample this probability and getting > + * the same result twice in a row, given these samples are fully > + * independent, is then given by P(n)^2, provided our sample period > + * is sufficiently short compared to the usage pattern. > + * > + * This quadric squishes small probabilities, making it less likely > + * we act on an unlikely CPU_node<->page relation. > + */ > > If this was the basis for the sched/numa patch then I'd point out that > I'm not the only person that failed to preserve history perfectly. > Which to be clear, it isn't. The original source is sched/numa according to https://lkml.org/lkml/2012/8/22/629 -- Mel Gorman SUSE Labs