From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758410Ab0GVHkW (ORCPT ); Thu, 22 Jul 2010 03:40:22 -0400 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:34550 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753185Ab0GVHkV (ORCPT ); Thu, 22 Jul 2010 03:40:21 -0400 Date: Thu, 22 Jul 2010 08:39:17 +0100 From: Russell King - ARM Linux To: Zach Pfeffer Cc: FUJITA Tomonori , ebiederm@xmission.com, linux-arch@vger.kernel.org, dwalker@codeaurora.org, mel@csn.ul.ie, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, andi@firstfloor.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [RFC 1/3 v3] mm: iommu: An API to unify IOMMU, CPU and device memory management Message-ID: <20100722073917.GC6802@n2100.arm.linux.org.uk> References: <20100715014148.GC2239@codeaurora.org> <20100719082213.GA7421@n2100.arm.linux.org.uk> <20100720221959.GC12250@codeaurora.org> <20100721104356S.fujita.tomonori@lab.ntt.co.jp> <20100722043034.GC22559@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100722043034.GC22559@codeaurora.org> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 21, 2010 at 09:30:34PM -0700, Zach Pfeffer wrote: > This goes to the nub of the issue. We need a lot of 1 MB physically > contiguous chunks. The system is going to fragment and we'll never get > our 12 1 MB chunks that we'll need, since the DMA API allocator uses > the system pool it will never succeed. By the "DMA API allocator" I assume you mean the coherent DMA interface, The DMA coherent API and DMA streaming APIs are two separate sub-interfaces of the DMA API and are not dependent on each other.