From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp-gw11.han.skanova.net ([81.236.55.20]:36794 "EHLO smtp-gw11.han.skanova.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756983Ab0HDKDo (ORCPT ); Wed, 4 Aug 2010 06:03:44 -0400 Message-ID: <4C593AF7.3060506@pelagicore.com> Date: Wed, 04 Aug 2010 12:03:35 +0200 From: =?UTF-8?B?UmljaGFyZCBSw7ZqZm9ycw==?= MIME-Version: 1.0 To: Pawel Osciak CC: 'Linux Media Mailing List' , 'Mauro Carvalho Chehab' , 'Douglas Schilling Landgraf' , 'Samuel Ortiz' Subject: Re: [PATCH 1/3 v2] media: Add a cached version of the contiguous video buffers References: <1280848711.19898.161.camel@debian> <000d01cb33aa$606faee0$214f0ca0$%osciak@samsung.com> <4C593586.6030804@pelagicore.com> <000e01cb33ba$796f44e0$6c4dcea0$%osciak@samsung.com> In-Reply-To: <000e01cb33ba$796f44e0$6c4dcea0$%osciak@samsung.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 08/04/2010 11:50 AM, Pawel Osciak wrote: >> >> How do you propose to allocate the buffers? They need to be contiguous >> and using uncached memory gave really bad performance. > > 829440 bytes is a quite a lot and one can't reliably depend on kmalloc > to be able to allocate such big chunks of contiguous memory. Were you > testing this on a freshly rebooted system? The systems have been running for a while, but not days. I don't see why would dma_alloc_coherent work better than kmalloc? I suppose bootmem could be used, or allocate the buffers at startup before memory gets fragmented. --Richard