Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754096AbYBRNaW (ORCPT ); Mon, 18 Feb 2008 08:30:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760358AbYBRN3y (ORCPT ); Mon, 18 Feb 2008 08:29:54 -0500 Received: from nat-132.atmel.no ([80.232.32.132]:62088 "EHLO relay.atmel.no" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1760315AbYBRN3w (ORCPT ); Mon, 18 Feb 2008 08:29:52 -0500 Date: Mon, 18 Feb 2008 14:29:49 +0100 From: Haavard Skinnemoen To: "Nelson, Shannon" Cc: "Haavard Skinnemoen" , "Williams, Dan J" , , "David Brownell" , , "Francis Moreau" , "Paul Mundt" , "Vladimir A. Barinov" , "Pierre Ossman" Subject: Re: [RFC v3 4/7] dmaengine: Add slave DMA interface Message-ID: <20080218142949.2c5b2810@dhcp-252-066.norway.atmel.com> In-Reply-To: References: <1202834638-9009-1-git-send-email-hskinnemoen@atmel.com> <1202834638-9009-2-git-send-email-hskinnemoen@atmel.com> <1202834638-9009-3-git-send-email-hskinnemoen@atmel.com> <1202834638-9009-4-git-send-email-hskinnemoen@atmel.com> <20080213202402.22818482@siona> <20080215105302.1e4251a3@dhcp-252-066.norway.atmel.com> Organization: Atmel Norway X-Mailer: Claws Mail 3.2.0 (GTK+ 2.12.5; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1134 Lines: 24 On Fri, 15 Feb 2008 09:12:35 -0800 "Nelson, Shannon" wrote: > I'll jump in here briefly - I'm okay with the direction this is going, > but I want to be protective of ioatdma performance. As used in struct > ioat_desc_sw, the cookie and ack elements end up very close to the end > of a cache line and I'd like them to not get pushed out across the > boundry. I don't think this proposal changes the layout, I'm just > bringing up my concern. Sure, performance is very important, and it's good to see that you're critical about the changes I'm proposing. That said, the memory layout doesn't change at all with this patch -- the fields that didn't go into the generic dma descriptor were at the end of the struct to begin with. I can add a comment saying that cookie and ack must always come first. Any other fields that we need to be careful about? Haavard -- 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/