From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755473Ab3F1KM5 (ORCPT ); Fri, 28 Jun 2013 06:12:57 -0400 Received: from e8.ny.us.ibm.com ([32.97.182.138]:50757 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754779Ab3F1KM4 (ORCPT ); Fri, 28 Jun 2013 06:12:56 -0400 Date: Fri, 28 Jun 2013 15:42:45 +0530 From: Srikar Dronamraju To: Peter Zijlstra Cc: Mel Gorman , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML Subject: Re: [PATCH 7/8] sched: Split accounting of NUMA hinting faults that pass two-stage filter Message-ID: <20130628101245.GD8362@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <1372257487-9749-1-git-send-email-mgorman@suse.de> <1372257487-9749-8-git-send-email-mgorman@suse.de> <20130628070027.GD17195@linux.vnet.ibm.com> <20130628093625.GF29209@dyad.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20130628093625.GF29209@dyad.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13062810-0320-0000-0000-00000015EF51 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > > > > Ideally it would be possible to distinguish between NUMA hinting faults > > > that are private to a task and those that are shared. This would require > > > that the last task that accessed a page for a hinting fault would be > > > recorded which would increase the size of struct page. Instead this patch > > > approximates private pages by assuming that faults that pass the two-stage > > > filter are private pages and all others are shared. The preferred NUMA > > > node is then selected based on where the maximum number of approximately > > > private faults were measured. > > > > Should we consider only private faults for preferred node? > > I don't think so; its optimal for the task to be nearest most of its pages; > irrespective of whether they be private or shared. Then the preferred node should have been chosen based on both the private and shared faults and not just private faults. > > > I would think if tasks have shared pages then moving all tasks that share > > the same pages to a node where the share pages are around would be > > preferred. No? > > Well no; not if there's only 5 shared pages but 1024 private pages. Yes, agree, but should we try to give the shared pages some additional weightage? -- Thanks and Regards Srikar Dronamraju