From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752747Ab3HBT46 (ORCPT ); Fri, 2 Aug 2013 15:56:58 -0400 Received: from merlin.infradead.org ([205.233.59.134]:58119 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751090Ab3HBT45 (ORCPT ); Fri, 2 Aug 2013 15:56:57 -0400 Date: Fri, 2 Aug 2013 21:56:39 +0200 From: Peter Zijlstra To: Don Morris Cc: Mel Gorman , Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML , riel@redhat.com Subject: Re: [PATCH] mm, numa: Do not group on RO pages Message-ID: <20130802195639.GU27162@twins.programming.kicks-ass.net> References: <1373901620-2021-1-git-send-email-mgorman@suse.de> <20130730113857.GR3008@twins.programming.kicks-ass.net> <20130731150751.GA15144@twins.programming.kicks-ass.net> <51F93105.8020503@hp.com> <20130802164715.GP27162@twins.programming.kicks-ass.net> <20130802165032.GQ27162@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130802165032.GQ27162@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > + /* > + * Avoid grouping on DSO/COW pages in specific and RO pages > + * in general, RO pages shouldn't hurt as much anyway since > + * they can be in shared cache state. > + */ OK, so that comment is crap. Its that you cannot work into RO pages and this RO pages don't establish a collaboration. > + if (page_mapcount(page) != 1 && !pmd_write(pmd)) > + flags |= TNF_NO_GROUP; Rik also noted that mapcount == 1 will trivially not form groups. This should indeed be so but I didn't test it without that clause. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx188.postini.com [74.125.245.188]) by kanga.kvack.org (Postfix) with SMTP id 9E5FB6B0032 for ; Fri, 2 Aug 2013 15:56:53 -0400 (EDT) Date: Fri, 2 Aug 2013 21:56:39 +0200 From: Peter Zijlstra Subject: Re: [PATCH] mm, numa: Do not group on RO pages Message-ID: <20130802195639.GU27162@twins.programming.kicks-ass.net> References: <1373901620-2021-1-git-send-email-mgorman@suse.de> <20130730113857.GR3008@twins.programming.kicks-ass.net> <20130731150751.GA15144@twins.programming.kicks-ass.net> <51F93105.8020503@hp.com> <20130802164715.GP27162@twins.programming.kicks-ass.net> <20130802165032.GQ27162@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130802165032.GQ27162@twins.programming.kicks-ass.net> Sender: owner-linux-mm@kvack.org List-ID: To: Don Morris Cc: Mel Gorman , Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML , riel@redhat.com > + /* > + * Avoid grouping on DSO/COW pages in specific and RO pages > + * in general, RO pages shouldn't hurt as much anyway since > + * they can be in shared cache state. > + */ OK, so that comment is crap. Its that you cannot work into RO pages and this RO pages don't establish a collaboration. > + if (page_mapcount(page) != 1 && !pmd_write(pmd)) > + flags |= TNF_NO_GROUP; Rik also noted that mapcount == 1 will trivially not form groups. This should indeed be so but I didn't test it without that clause. -- 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