Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932130AbWAJAeH (ORCPT ); Mon, 9 Jan 2006 19:34:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932132AbWAJAeH (ORCPT ); Mon, 9 Jan 2006 19:34:07 -0500 Received: from warden-p.diginsite.com ([208.29.163.248]:58842 "HELO warden.diginsite.com") by vger.kernel.org with SMTP id S932130AbWAJAeG (ORCPT ); Mon, 9 Jan 2006 19:34:06 -0500 Date: Mon, 9 Jan 2006 16:29:45 -0800 (PST) From: David Lang X-X-Sender: dlang@dlang.diginsite.com To: John Rigg cc: =?iso-8859-1?Q?Ren=E9?= Rebe , Hannu Savolainen , Jaroslav Kysela , Takashi Iwai , linux-sound@vger.kernel.org, ALSA development , LKML Subject: Re: [Alsa-devel] Re: [OT] ALSA userspace API complexity In-Reply-To: <20060110001617.GA5154@localhost.localdomain> Message-ID: References: <20050726150837.GT3160@stusta.de> <200601091405.23939.rene@exactcode.de> <200601091812.55943.rene@exactcode.de> <20060109232043.GA5013@localhost.localdomain> <20060110001617.GA5154@localhost.localdomain> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1057 Lines: 24 On Tue, 10 Jan 2006, John Rigg wrote: >> does the CPU touch the data for these, or do you DMA directly from >> userspace (i.e. "zero-copy")? > > The cards I mentioned use DMA. RME actually advertises that some of their > cards can handle 52 channels with zero CPU load. Their onboard DSPs can > also do routing and mixing, again without touching the CPU. I was under the (apparently mistaken) impression that you couldn't DMA from userspace (something to do with the possibility that the userspace memory pages could be swapped out in the middle of the DMA) David Lang -- There are two ways of constructing a software design. One way is to make it so simple that there are obviously no deficiencies. And the other way is to make it so complicated that there are no obvious deficiencies. -- C.A.R. Hoare - 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/