Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756704AbZD0Hso (ORCPT ); Mon, 27 Apr 2009 03:48:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756099AbZD0HsY (ORCPT ); Mon, 27 Apr 2009 03:48:24 -0400 Received: from an-out-0708.google.com ([209.85.132.247]:41978 "EHLO an-out-0708.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756376AbZD0HsX (ORCPT ); Mon, 27 Apr 2009 03:48:23 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=f6i5fGQCp8x5tMI9qHlJeNEdw90a7n9LZhrCiw9Ec438HOsorvfXKvZD0tvM9yHz3s sWTT7wFGu9VWJGTnx2+Nki5mufhSrUe8vVZb0j98/wy2ESsz+lUMCSlnvx+5No0bc1Nn YR+UNCFmUjZ/RIZbFfsQMGNKNdgMql02Lx7yA= MIME-Version: 1.0 In-Reply-To: <20090424183517.GB23140@ovro.caltech.edu> References: <20090424183517.GB23140@ovro.caltech.edu> Date: Mon, 27 Apr 2009 15:48:21 +0800 X-Google-Sender-Auth: d0f7d8123b4c6827 Message-ID: <2a27d3730904270048g1e247797s6a25f9e28d664214@mail.gmail.com> Subject: Re: [PATCH] fsldma: use PCI Read Multiple command From: Li Yang To: Ira Snyder Cc: linux-kernel@vger.kernel.org, Dan Williams , linuxppc-dev@ozlabs.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1169 Lines: 26 On Sat, Apr 25, 2009 at 2:35 AM, Ira Snyder wrote: > By default, the Freescale 83xx DMA controller uses the PCI Read Line > command when reading data over the PCI bus. Setting the controller to use > the PCI Read Multiple command instead allows the controller to read much > larger bursts of data, which provides a drastic speed increase. > > The slowdown due to using PCI Read Line was only observed when a PCI-to-PCI > bridge was between the devices trying to communicate. > > A simple test driver showed an increase from 4MB/sec to 116MB/sec when > performing DMA over the PCI bus. Using DMA to transfer between blocks of > local SDRAM showed no change in performance with this patch. The dmatest > driver was also used to verify the correctness of the transfers, and showed > no errors. > > Signed-off-by: Ira W. Snyder Acked-by: Li Yang Thanks, Leo -- 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/