From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752180Ab3AHGuw (ORCPT ); Tue, 8 Jan 2013 01:50:52 -0500 Received: from mailout1.w1.samsung.com ([210.118.77.11]:39976 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751054Ab3AHGuv (ORCPT ); Tue, 8 Jan 2013 01:50:51 -0500 X-AuditID: cbfec7f5-b7fd76d000007247-d5-50ebc1c9b2a9 Message-id: <50EBC1C1.3060208@samsung.com> Date: Tue, 08 Jan 2013 07:50:41 +0100 From: Marek Szyprowski User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-version: 1.0 To: Mauro Carvalho Chehab Cc: Jonathan Corbet , Alessandro Rubini , federico.vaga@gmail.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, s.nawrocki@samsung.com Subject: Re: [PATCH v3 2/4] videobuf2-dma-streaming: new videobuf2 memory allocator References: <3892735.vLSnhhCRFi@harkonnen> <1348484332-8106-1-git-send-email-federico.vaga@gmail.com> <1399400.izKZgEHXnP@harkonnen> <12929800.xFTBAueAE0@harkonnen> <20130106230947.GA17979@mail.gnudd.com> <20130107124050.3fc5031b@lwn.net> <20130107181500.24c56803@redhat.com> In-reply-to: <20130107181500.24c56803@redhat.com> Content-type: text/plain; charset=UTF-8; format=flowed Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprILMWRmVeSWpSXmKPExsVy+t/xK7onD74OMLg9lcXi8q45bBY9G7ay OjB5fN4kF8AYxWWTkpqTWZZapG+XwJWxtPskW8FBjoqv/WeYGhivs3UxcnJICJhIXPx6mQnC FpO4cG89UJyLQ0hgKaPE3slNLCAJIYFmJolvLQkgNq+AlsS85xPB4iwCqhLHFzwBG8QmYCjR 9bYLzBYV8JWY9usaE0S9oMSPyfeA6jk4RAT0JLqaBEDmMwtMZ5I4s+MWO0iNsECoxJv/r5gg Fs9mkvjZ9pgVJMEJNPRQ/wJGEJtZwEziUcs6ZghbXmLzmrfMExgFZiHZMQtJ2SwkZQsYmVcx iqaWJhcUJ6XnGukVJ+YWl+al6yXn525ihATj1x2MS49ZHWIU4GBU4uG9GPM6QIg1say4MvcQ owQHs5IIr/0+oBBvSmJlVWpRfnxRaU5q8SFGJg5OqQZG1hml91l2NBW93l37dW2vV0t91kev v4sf6y25onTQ9az4vt8eK7fYP5A58ic8/1rQD6/0CsYkjsy3L/P0C/pYRX3+7738wzWli/eR yPX7tgpFvd+kL0+zz93COHFvTeGaL78YTeY2K4dwmyfznombmD9bXTJF70n64TVnlnGJfnRt y3BYFfxOiaU4I9FQi7moOBEA5VonSyQCAAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/7/2013 9:15 PM, Mauro Carvalho Chehab wrote: > Em Mon, 7 Jan 2013 12:40:50 -0700 > Jonathan Corbet escreveu: > > > On Mon, 7 Jan 2013 00:09:47 +0100 > > Alessandro Rubini wrote: > > > > > 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. > > > > It made the difference between 10 frames per second with the CPU running > > flat out and 30fps mostly idle. I think that probably counts as > > meaningful, yeah...:) > > Couldn't this performance difference be due to the usage of GFP_DMA inside > the VB2 code, like Federico's new patch series is proposing? > > If not, why are there a so large performance penalty? Nope, this was caused rather by a very poor CPU access to non-cached (aka 'coherent') memory and the way the video data has been accessed/read with CPU. Best regards -- Marek Szyprowski Samsung Poland R&D Center