From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753167Ab1FNSbE (ORCPT ); Tue, 14 Jun 2011 14:31:04 -0400 Received: from moutng.kundenserver.de ([212.227.17.9]:62592 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752108Ab1FNSbC (ORCPT ); Tue, 14 Jun 2011 14:31:02 -0400 From: Arnd Bergmann To: "Michal Nazarewicz" Subject: Re: [PATCH 08/10] mm: cma: Contiguous Memory Allocator added Date: Tue, 14 Jun 2011 20:30:07 +0200 User-Agent: KMail/1.13.6 (Linux/3.0.0-rc1nosema+; KDE/4.6.3; x86_64; ; ) Cc: "Marek Szyprowski" , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linux-mm@kvack.org, linaro-mm-sig@lists.linaro.org, "'Kyungmin Park'" , "'Andrew Morton'" , "'KAMEZAWA Hiroyuki'" , "'Ankita Garg'" , "'Daniel Walker'" , "'Mel Gorman'" , "'Jesse Barker'" References: <1307699698-29369-1-git-send-email-m.szyprowski@samsung.com> <201106141803.00876.arnd@arndb.de> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201106142030.07549.arnd@arndb.de> X-Provags-ID: V02:K0:gAq7pKBxl+LLLpNrzx/c5ey6ShlHHmeHilpK5lYSpfm DWG323q2nPZgt61yNZPbl2r7C116fuFVOK55jsNDGn5qHPbc9D H7nPLNzCBdXRLANXIxk+GoAcxo3K3pvawt5n9I65THfHoubch/ Oc902jN0p60h2BjYOfGs/c/fxpjrcrUoRAvqMLcWKBnd6KTbmk 2Zq7J9hn2wYUpqEn+meaQ== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 14 June 2011 18:58:35 Michal Nazarewicz wrote: > On Tue, 14 Jun 2011 18:03:00 +0200, Arnd Bergmann wrote: > > For all I know, that is something that is only true for a few very > > special Samsung devices, > > Maybe. I'm just answering your question. :) > > Ah yes, I forgot that separate regions for different purposes could > decrease fragmentation. That is indeed a good point, but having a good allocator algorithm could also solve this. I don't know too much about these allocation algorithms, but there are probably multiple working approaches to this. > > I would suggest going forward without having multiple regions: > > Is having support for multiple regions a bad thing? Frankly, > removing this support will change code from reading context passed > as argument to code reading context from global variable. Nothing > is gained; functionality is lost. What is bad IMHO is making them the default, which forces the board code to care about memory management details. I would much prefer to have contiguous allocation parameters tuned automatically to just work on most boards before we add ways to do board-specific hacks. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id 8AD226B0012 for ; Tue, 14 Jun 2011 14:30:40 -0400 (EDT) From: Arnd Bergmann Subject: Re: [PATCH 08/10] mm: cma: Contiguous Memory Allocator added Date: Tue, 14 Jun 2011 20:30:07 +0200 References: <1307699698-29369-1-git-send-email-m.szyprowski@samsung.com> <201106141803.00876.arnd@arndb.de> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201106142030.07549.arnd@arndb.de> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Nazarewicz Cc: Marek Szyprowski , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, linux-mm@kvack.org, linaro-mm-sig@lists.linaro.org, 'Kyungmin Park' , 'Andrew Morton' , 'KAMEZAWA Hiroyuki' , 'Ankita Garg' , 'Daniel Walker' , 'Mel Gorman' , 'Jesse Barker' On Tuesday 14 June 2011 18:58:35 Michal Nazarewicz wrote: > On Tue, 14 Jun 2011 18:03:00 +0200, Arnd Bergmann wrote: > > For all I know, that is something that is only true for a few very > > special Samsung devices, > > Maybe. I'm just answering your question. :) > > Ah yes, I forgot that separate regions for different purposes could > decrease fragmentation. That is indeed a good point, but having a good allocator algorithm could also solve this. I don't know too much about these allocation algorithms, but there are probably multiple working approaches to this. > > I would suggest going forward without having multiple regions: > > Is having support for multiple regions a bad thing? Frankly, > removing this support will change code from reading context passed > as argument to code reading context from global variable. Nothing > is gained; functionality is lost. What is bad IMHO is making them the default, which forces the board code to care about memory management details. I would much prefer to have contiguous allocation parameters tuned automatically to just work on most boards before we add ways to do board-specific hacks. Arnd -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Tue, 14 Jun 2011 20:30:07 +0200 Subject: [PATCH 08/10] mm: cma: Contiguous Memory Allocator added In-Reply-To: References: <1307699698-29369-1-git-send-email-m.szyprowski@samsung.com> <201106141803.00876.arnd@arndb.de> Message-ID: <201106142030.07549.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tuesday 14 June 2011 18:58:35 Michal Nazarewicz wrote: > On Tue, 14 Jun 2011 18:03:00 +0200, Arnd Bergmann wrote: > > For all I know, that is something that is only true for a few very > > special Samsung devices, > > Maybe. I'm just answering your question. :) > > Ah yes, I forgot that separate regions for different purposes could > decrease fragmentation. That is indeed a good point, but having a good allocator algorithm could also solve this. I don't know too much about these allocation algorithms, but there are probably multiple working approaches to this. > > I would suggest going forward without having multiple regions: > > Is having support for multiple regions a bad thing? Frankly, > removing this support will change code from reading context passed > as argument to code reading context from global variable. Nothing > is gained; functionality is lost. What is bad IMHO is making them the default, which forces the board code to care about memory management details. I would much prefer to have contiguous allocation parameters tuned automatically to just work on most boards before we add ways to do board-specific hacks. Arnd