Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754083Ab1FOIg7 (ORCPT ); Wed, 15 Jun 2011 04:36:59 -0400 Received: from mailout2.w1.samsung.com ([210.118.77.12]:25354 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754002Ab1FOIgx (ORCPT ); Wed, 15 Jun 2011 04:36:53 -0400 Date: Wed, 15 Jun 2011 10:36:18 +0200 From: Marek Szyprowski Subject: RE: [Linaro-mm-sig] [PATCH 08/10] mm: cma: Contiguous Memory Allocator added In-reply-to: <201106142242.25157.arnd@arndb.de> To: "'Arnd Bergmann'" , "'Zach Pfeffer'" Cc: linux-arm-kernel@lists.infradead.org, "'Daniel Walker'" , "'Daniel Stone'" , linux-mm@kvack.org, "'Mel Gorman'" , linux-kernel@vger.kernel.org, "'Michal Nazarewicz'" , linaro-mm-sig@lists.linaro.org, "'Jesse Barker'" , "'Kyungmin Park'" , "'Ankita Garg'" , "'Andrew Morton'" , "'KAMEZAWA Hiroyuki'" , linux-media@vger.kernel.org, Marek Szyprowski Message-id: <000901cc2b37$4c21f030$e465d090$%szyprowski@samsung.com> Organization: SPRC MIME-version: 1.0 X-Mailer: Microsoft Office Outlook 12.0 Content-type: text/plain; charset=us-ascii Content-language: pl Content-transfer-encoding: 7BIT Thread-index: Acwq08w+hLuENvqsQ6WxCs8SVZBnZAAV+1Dg References: <1307699698-29369-1-git-send-email-m.szyprowski@samsung.com> <20110614170158.GU2419@fooishbar.org> <201106142242.25157.arnd@arndb.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2012 Lines: 48 Hello, On Tuesday, June 14, 2011 10:42 PM Arnd Bergmann wrote: > On Tuesday 14 June 2011 20:58:25 Zach Pfeffer wrote: > > I've seen this split bank allocation in Qualcomm and TI SoCs, with > > Samsung, that makes 3 major SoC vendors (I would be surprised if > > Nvidia didn't also need to do this) - so I think some configurable > > method to control allocations is necessarily. The chips can't do > > decode without it (and by can't do I mean 1080P and higher decode is > > not functionally useful). Far from special, this would appear to be > > the default. > > Thanks for the insight, that's a much better argument than 'something > may need it'. Are those all chips without an IOMMU or do we also > need to solve the IOMMU case with split bank allocation? > > I think I'd still prefer to see the support for multiple regions split > out into one of the later patches, especially since that would defer > the question of how to do the initialization for this case and make > sure we first get a generic way. > > You've convinced me that we need to solve the problem of allocating > memory from a specific bank eventually, but separating it from the > one at hand (contiguous allocation) should help getting the important > groundwork in at first. > > The possible conflict that I still see with per-bank CMA regions are: > > * It completely destroys memory power management in cases where that > is based on powering down entire memory banks. I don't think that per-bank CMA regions destroys memory power management more than the global CMA pool. Please note that the contiguous buffers (or in general dma-buffers) right now are unmovable so they don't fit well into memory power management. Best regards -- Marek Szyprowski Samsung Poland R&D Center -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/