From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e8.ny.us.ibm.com (e8.ny.us.ibm.com [32.97.182.138]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e8.ny.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 57004B70F6 for ; Wed, 29 Sep 2010 01:21:42 +1000 (EST) Received: from d01relay01.pok.ibm.com (d01relay01.pok.ibm.com [9.56.227.233]) by e8.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id o8SF2aB2003434 for ; Tue, 28 Sep 2010 11:02:36 -0400 Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay01.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o8SFLdKc385416 for ; Tue, 28 Sep 2010 11:21:39 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id o8SFLapb011105 for ; Tue, 28 Sep 2010 12:21:38 -0300 Subject: Re: [PATCH 6/8] v2 Update node sysfs code From: Dave Hansen To: Robin Holt In-Reply-To: <20100928092919.GF14068@sgi.com> References: <4CA0EBEB.1030204@austin.ibm.com> <4CA0F00D.9000702@austin.ibm.com> <20100928092919.GF14068@sgi.com> Content-Type: text/plain; charset="ANSI_X3.4-1968" Date: Tue, 28 Sep 2010 08:21:33 -0700 Message-ID: <1285687293.19976.6172.camel@nimitz> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, Greg KH , linux-kernel@vger.kernel.org, linux-mm@kvack.org, KAMEZAWA Hiroyuki List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, 2010-09-28 at 04:29 -0500, Robin Holt wrote: > Also, I don't think I much care for the weirdness that occurs if a > memory block spans two nodes. I have not thought through how possible > (or likely) this is, but the code certainly permits it. If that were > the case, how would we know which sections need to be taken offline, > etc? Since the architecture is the one doing the memory_block_size_bytes() override, I'd expect that the per-arch code knows enough to ensure that this doesn't happen. It's probably something to add to the documentation or the patch descriptions. "How should an architecture define this? When should it be overridden?" It's just like the question of SECTION_SIZE. What if a section spans a node? Well, they don't because the sections are a software concept and we _define_ them to not be able to cross nodes. If they do, just make them smaller. -- Dave From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756798Ab0I1PVn (ORCPT ); Tue, 28 Sep 2010 11:21:43 -0400 Received: from e8.ny.us.ibm.com ([32.97.182.138]:50694 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754383Ab0I1PVm (ORCPT ); Tue, 28 Sep 2010 11:21:42 -0400 Subject: Re: [PATCH 6/8] v2 Update node sysfs code From: Dave Hansen To: Robin Holt Cc: Nathan Fontenot , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@ozlabs.org, Greg KH , KAMEZAWA Hiroyuki In-Reply-To: <20100928092919.GF14068@sgi.com> References: <4CA0EBEB.1030204@austin.ibm.com> <4CA0F00D.9000702@austin.ibm.com> <20100928092919.GF14068@sgi.com> Content-Type: text/plain; charset="ANSI_X3.4-1968" Date: Tue, 28 Sep 2010 08:21:33 -0700 Message-ID: <1285687293.19976.6172.camel@nimitz> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2010-09-28 at 04:29 -0500, Robin Holt wrote: > Also, I don't think I much care for the weirdness that occurs if a > memory block spans two nodes. I have not thought through how possible > (or likely) this is, but the code certainly permits it. If that were > the case, how would we know which sections need to be taken offline, > etc? Since the architecture is the one doing the memory_block_size_bytes() override, I'd expect that the per-arch code knows enough to ensure that this doesn't happen. It's probably something to add to the documentation or the patch descriptions. "How should an architecture define this? When should it be overridden?" It's just like the question of SECTION_SIZE. What if a section spans a node? Well, they don't because the sections are a software concept and we _define_ them to not be able to cross nodes. If they do, just make them smaller. -- Dave From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id D0B546B0047 for ; Tue, 28 Sep 2010 11:21:40 -0400 (EDT) Received: from d01relay03.pok.ibm.com (d01relay03.pok.ibm.com [9.56.227.235]) by e2.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id o8SF6Yii011876 for ; Tue, 28 Sep 2010 11:06:34 -0400 Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay03.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o8SFLcok344228 for ; Tue, 28 Sep 2010 11:21:38 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id o8SFLapZ011105 for ; Tue, 28 Sep 2010 12:21:38 -0300 Subject: Re: [PATCH 6/8] v2 Update node sysfs code From: Dave Hansen In-Reply-To: <20100928092919.GF14068@sgi.com> References: <4CA0EBEB.1030204@austin.ibm.com> <4CA0F00D.9000702@austin.ibm.com> <20100928092919.GF14068@sgi.com> Content-Type: text/plain; charset="ANSI_X3.4-1968" Date: Tue, 28 Sep 2010 08:21:33 -0700 Message-ID: <1285687293.19976.6172.camel@nimitz> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Robin Holt Cc: Nathan Fontenot , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@ozlabs.org, Greg KH , KAMEZAWA Hiroyuki List-ID: On Tue, 2010-09-28 at 04:29 -0500, Robin Holt wrote: > Also, I don't think I much care for the weirdness that occurs if a > memory block spans two nodes. I have not thought through how possible > (or likely) this is, but the code certainly permits it. If that were > the case, how would we know which sections need to be taken offline, > etc? Since the architecture is the one doing the memory_block_size_bytes() override, I'd expect that the per-arch code knows enough to ensure that this doesn't happen. It's probably something to add to the documentation or the patch descriptions. "How should an architecture define this? When should it be overridden?" It's just like the question of SECTION_SIZE. What if a section spans a node? Well, they don't because the sections are a software concept and we _define_ them to not be able to cross nodes. If they do, just make them smaller. -- Dave -- 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