Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758810AbYBSSzX (ORCPT ); Tue, 19 Feb 2008 13:55:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753954AbYBSSzK (ORCPT ); Tue, 19 Feb 2008 13:55:10 -0500 Received: from mga03.intel.com ([143.182.124.21]:34665 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754138AbYBSSzI convert rfc822-to-8bit (ORCPT ); Tue, 19 Feb 2008 13:55:08 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.25,377,1199692800"; d="scan'208";a="380993663" X-MimeOLE: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Subject: RE: [RFC v3 4/7] dmaengine: Add slave DMA interface Date: Tue, 19 Feb 2008 10:46:54 -0800 Message-ID: In-Reply-To: <20080218142949.2c5b2810@dhcp-252-066.norway.atmel.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [RFC v3 4/7] dmaengine: Add slave DMA interface Thread-Index: AchyMocGe8DwhdQQTTCA6Lj6bM/kdwA9NV4g 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> <20080218142949.2c5b2810@dhcp-252-066.norway.atmel.com> From: "Nelson, Shannon" To: "Haavard Skinnemoen" Cc: "Williams, Dan J" , X-OriginalArrivalTime: 19 Feb 2008 18:46:54.0469 (UTC) FILETIME=[CC11B350:01C87327] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1698 Lines: 44 >From: Haavard Skinnemoen [mailto:hskinnemoen@atmel.com] >Sent: Monday, February 18, 2008 5:30 AM >To: Nelson, Shannon >Cc: Haavard Skinnemoen; Williams, Dan J; >linux-kernel@vger.kernel.org; David Brownell; >kernel@avr32linux.org; Francis Moreau; Paul Mundt; Vladimir A. >Barinov; Pierre Ossman >Subject: Re: [RFC v3 4/7] dmaengine: Add slave DMA interface > >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 > Those are the only two that I'm worried about at the moment. I'm just hoping that a quirk in some compiler's struct packing doesn't push them over that edge. Thanks, sln -- 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/