From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752655AbbJEPdF (ORCPT ); Mon, 5 Oct 2015 11:33:05 -0400 Received: from mga01.intel.com ([192.55.52.88]:19493 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751391AbbJEPdC (ORCPT ); Mon, 5 Oct 2015 11:33:02 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.17,639,1437462000"; d="scan'208";a="819795127" Date: Mon, 5 Oct 2015 16:32:58 +0100 From: Vinod Koul To: Peter Ujfalusi Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, linux@arm.linux.org.uk, misael.lopez@ti.com Subject: Re: [PATCH] dmaengine: omap-dma: Enable packed accesses for cyclic transfers Message-ID: <20151005153258.GF13501@vkoul-mobl.iind.intel.com> References: <1442233865-10412-1-git-send-email-peter.ujfalusi@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1442233865-10412-1-git-send-email-peter.ujfalusi@ti.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 14, 2015 at 03:31:05PM +0300, Peter Ujfalusi wrote: > From: Misael Lopez Cruz > > The L3 throughput can be higher than expected when packed access > is not enabled. The ratio depends on the number of bytes in a > transaction and the EMIF interface width. > > The throughput was measured for the following settings/cases: > > * Case 1: Burst size of 64 bytes, packed access disabled > * Case 2: Burst size of 64 bytes, packed access enabled > * Case 3: Burst disabled, packed access disabled > > Throughput measurements were done during McASP-based audio > playback on the Jacinto6 EVM using the omapconf tool [1]: > $ omapconf trace bw -m sdma_rd > > --------------------------------------------------------- > Throughput (MB/s) > Audio parameters Case 1 Case 2 Case 3 > --------------------------------------------------------- > 44.1kHz, 16-bits, stereo 1.41 0.18 1.41 > 44.1kHz, 32-bits, stereo 1.41 0.35 1.41 > 44.1kHz, 16-bits, 4-chan 2.82 0.35 2.82 > 44.1kHz, 16-bits, 6-chan 4.23 0.53 4.23 > 44.1kHz, 16-bits, 8-chan 5.64 0.71 5.64 > --------------------------------------------------------- > > From above measurements, case 2 is the only one that delivers > the expected throughput for the given audio parameters. For > that reason, the packed accesses are now enabled. > > It's worth to mention that packed accesses cannot be enabled > for all addressing modes. In cyclic transfers, it can be > enabled in the source for MEM_TO_DEV and in dest for DEV_TO_MEM, > as they use post-increment mode which supports packed accesses. > > Peter Ujfalusi: > From the TRM regarding to this: > "NOTE: Except in the constant addressing mode, the source or > destination must be specified as packed for burst transactions > to occur." > > So w/o the packed setting the burst on the MEM side was not > enabled, this explains the numbers. > > [1] https://github.com/omapconf/omapconf > Applied, thanks -- ~Vinod