From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753305Ab3AFXKn (ORCPT ); Sun, 6 Jan 2013 18:10:43 -0500 Received: from mail2.gnudd.com ([213.203.150.91]:59800 "EHLO mail.gnudd.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753228Ab3AFXKk (ORCPT ); Sun, 6 Jan 2013 18:10:40 -0500 Date: Mon, 7 Jan 2013 00:09:47 +0100 From: Alessandro Rubini To: federico.vaga@gmail.com Cc: mchehab@redhat.com, m.szyprowski@samsung.com, mchehab@infradead.org, pawel@osciak.com, hans.verkuil@cisco.com, giancarlo.asnaghi@st.com, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, corbet@lwn.net, s.nawrocki@samsung.com Subject: Re: [PATCH v3 2/4] videobuf2-dma-streaming: new videobuf2 memory allocator Message-ID: <20130106230947.GA17979@mail.gnudd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Organization: GnuDD, Device Drivers, Embedded Systems, Courses In-Reply-To: <3892735.vLSnhhCRFi@harkonnen> References: <3892735.vLSnhhCRFi@harkonnen> <1348484332-8106-1-git-send-email-federico.vaga@gmail.com> <1399400.izKZgEHXnP@harkonnen> <12929800.xFTBAueAE0@harkonnen> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > The problem is that on the sta2x11 architecture only the first > 512MB are available through the PCI bus, but the allocator can allocate memory > for DMA above this limit. By using GFP_DMA flags the allocation take place > under the 16MB so it works. Still, you are not running the upstream allocator. IIUC, you added a "gfp_t" field in the platform data or somewhere, so the sta2x11 can request GFP_DMA to be OR'd, while other users remain unaffected. Will you please submit the patch to achieve that? > I cannot do performance test at the moment because I don't have the time, so I > cannot personally justify the presence of a new allocator. I don't expect you'll see serious performance differences on the PC. I think ARM users will have better benefits, due to the different cache architecture. You told me Jon measured meaningful figures on a Marvel CPU. > I will propose V4 patches soon. thanks /alessandro