From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757963Ab1FVNjd (ORCPT ); Wed, 22 Jun 2011 09:39:33 -0400 Received: from moutng.kundenserver.de ([212.227.17.8]:56291 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753372Ab1FVNjc (ORCPT ); Wed, 22 Jun 2011 09:39:32 -0400 From: Arnd Bergmann To: Marek Szyprowski Subject: Re: [Linaro-mm-sig] [PATCH 08/10] mm: cma: Contiguous =?iso-8859-1?q?Memory=09Allocator?= added Date: Wed, 22 Jun 2011 15:39:23 +0200 User-Agent: KMail/1.12.2 (Linux/2.6.31-22-generic; KDE/4.3.2; x86_64; ; ) Cc: "'Hans Verkuil'" , "'Daniel Walker'" , "'Jesse Barker'" , "'Mel Gorman'" , "'KAMEZAWA Hiroyuki'" , linux-kernel@vger.kernel.org, "'Michal Nazarewicz'" , linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, "'Kyungmin Park'" , "'Ankita Garg'" , "'Andrew Morton'" , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org References: <1307699698-29369-1-git-send-email-m.szyprowski@samsung.com> <201106221442.20848.arnd@arndb.de> <003701cc30de$7a159710$6e40c530$%szyprowski@samsung.com> In-Reply-To: <003701cc30de$7a159710$6e40c530$%szyprowski@samsung.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201106221539.24044.arnd@arndb.de> X-Provags-ID: V02:K0:6zQ21cYSAkHQCm2ZNGtwiE8sTS+2/BWJGFvJBgsse5x CkF32TggVNxMgkAVH/5VsUc2A6T8aaU+Ur1cQf9ihIvTLe2GZT teCkTPuOd/c+6rCkZfWeklmQ7VfbjnyMWFJR39D8hlpGQSWEX9 IqAKZ6l+3bmbrpeHKjUHw8bVh02kHLU3xwi235uTwFF0cgUCu4 fyrOtIQXdI6oNHaToi5fw== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 22 June 2011, Marek Szyprowski wrote: > Sounds really good, but it might be really hard to implemnt, at least for > CMA, because it needs to tweak parameters of memory management internal > structures very early, when buddy allocator has not been activated yet. Why that? I would expect you can do the same that hugepages (used to) do and just attempt high-order allocations. If they succeed, you can add them as a CMA region and free them again, into the movable set of pages, otherwise you just fail the request from user space when the memory is already fragmented. > > These essentially fight over the same memory (though things are slightly > > different with dynamic hugepages), and they all face the same basic problem > > of getting as much for themselves without starving the other three. > > I'm not sure we can solve all such issues in the first version. Maybe we should > first have each of the above fully working in mainline separately and then > start the integration works. Yes, makes sense. We just need to be careful not to introduce user-visible interfaces that we cannot change any more in the process. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from moutng.kundenserver.de ([212.227.17.8]:56291 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753372Ab1FVNjc (ORCPT ); Wed, 22 Jun 2011 09:39:32 -0400 From: Arnd Bergmann To: Marek Szyprowski Subject: Re: [Linaro-mm-sig] [PATCH 08/10] mm: cma: Contiguous =?iso-8859-1?q?Memory=09Allocator?= added Date: Wed, 22 Jun 2011 15:39:23 +0200 Cc: "'Hans Verkuil'" , "'Daniel Walker'" , "'Jesse Barker'" , "'Mel Gorman'" , "'KAMEZAWA Hiroyuki'" , linux-kernel@vger.kernel.org, "'Michal Nazarewicz'" , linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, "'Kyungmin Park'" , "'Ankita Garg'" , "'Andrew Morton'" , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org References: <1307699698-29369-1-git-send-email-m.szyprowski@samsung.com> <201106221442.20848.arnd@arndb.de> <003701cc30de$7a159710$6e40c530$%szyprowski@samsung.com> In-Reply-To: <003701cc30de$7a159710$6e40c530$%szyprowski@samsung.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201106221539.24044.arnd@arndb.de> List-ID: Sender: On Wednesday 22 June 2011, Marek Szyprowski wrote: > Sounds really good, but it might be really hard to implemnt, at least for > CMA, because it needs to tweak parameters of memory management internal > structures very early, when buddy allocator has not been activated yet. Why that? I would expect you can do the same that hugepages (used to) do and just attempt high-order allocations. If they succeed, you can add them as a CMA region and free them again, into the movable set of pages, otherwise you just fail the request from user space when the memory is already fragmented. > > These essentially fight over the same memory (though things are slightly > > different with dynamic hugepages), and they all face the same basic problem > > of getting as much for themselves without starving the other three. > > I'm not sure we can solve all such issues in the first version. Maybe we should > first have each of the above fully working in mainline separately and then > start the integration works. Yes, makes sense. We just need to be careful not to introduce user-visible interfaces that we cannot change any more in the process. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 808C2900194 for ; Wed, 22 Jun 2011 09:39:56 -0400 (EDT) From: Arnd Bergmann Subject: Re: [Linaro-mm-sig] [PATCH 08/10] mm: cma: Contiguous =?iso-8859-1?q?Memory=09Allocator?= added Date: Wed, 22 Jun 2011 15:39:23 +0200 References: <1307699698-29369-1-git-send-email-m.szyprowski@samsung.com> <201106221442.20848.arnd@arndb.de> <003701cc30de$7a159710$6e40c530$%szyprowski@samsung.com> In-Reply-To: <003701cc30de$7a159710$6e40c530$%szyprowski@samsung.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201106221539.24044.arnd@arndb.de> Sender: owner-linux-mm@kvack.org List-ID: To: Marek Szyprowski Cc: 'Hans Verkuil' , 'Daniel Walker' , 'Jesse Barker' , 'Mel Gorman' , 'KAMEZAWA Hiroyuki' , linux-kernel@vger.kernel.org, 'Michal Nazarewicz' , linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, 'Kyungmin Park' , 'Ankita Garg' , 'Andrew Morton' , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org On Wednesday 22 June 2011, Marek Szyprowski wrote: > Sounds really good, but it might be really hard to implemnt, at least for > CMA, because it needs to tweak parameters of memory management internal > structures very early, when buddy allocator has not been activated yet. Why that? I would expect you can do the same that hugepages (used to) do and just attempt high-order allocations. If they succeed, you can add them as a CMA region and free them again, into the movable set of pages, otherwise you just fail the request from user space when the memory is already fragmented. > > These essentially fight over the same memory (though things are slightly > > different with dynamic hugepages), and they all face the same basic problem > > of getting as much for themselves without starving the other three. > > I'm not sure we can solve all such issues in the first version. Maybe we should > first have each of the above fully working in mainline separately and then > start the integration works. Yes, makes sense. We just need to be careful not to introduce user-visible interfaces that we cannot change any more in the process. 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: Wed, 22 Jun 2011 15:39:23 +0200 Subject: [Linaro-mm-sig] [PATCH 08/10] mm: cma: Contiguous =?iso-8859-1?q?Memory=09Allocator?= added In-Reply-To: <003701cc30de$7a159710$6e40c530$%szyprowski@samsung.com> References: <1307699698-29369-1-git-send-email-m.szyprowski@samsung.com> <201106221442.20848.arnd@arndb.de> <003701cc30de$7a159710$6e40c530$%szyprowski@samsung.com> Message-ID: <201106221539.24044.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wednesday 22 June 2011, Marek Szyprowski wrote: > Sounds really good, but it might be really hard to implemnt, at least for > CMA, because it needs to tweak parameters of memory management internal > structures very early, when buddy allocator has not been activated yet. Why that? I would expect you can do the same that hugepages (used to) do and just attempt high-order allocations. If they succeed, you can add them as a CMA region and free them again, into the movable set of pages, otherwise you just fail the request from user space when the memory is already fragmented. > > These essentially fight over the same memory (though things are slightly > > different with dynamic hugepages), and they all face the same basic problem > > of getting as much for themselves without starving the other three. > > I'm not sure we can solve all such issues in the first version. Maybe we should > first have each of the above fully working in mainline separately and then > start the integration works. Yes, makes sense. We just need to be careful not to introduce user-visible interfaces that we cannot change any more in the process. Arnd