From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754830Ab2LCOBk (ORCPT ); Mon, 3 Dec 2012 09:01:40 -0500 Received: from webmail.solarflare.com ([12.187.104.25]:25528 "EHLO webmail.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754234Ab2LCOBi (ORCPT ); Mon, 3 Dec 2012 09:01:38 -0500 Message-ID: <1354543290.7030.26.camel@deadeye.wl.decadent.org.uk> Subject: Re: [PATCH] net/macb: Use dmapool to align descriptors on 64bits From: Ben Hutchings To: Nicolas Ferre CC: "David S. Miller" , , , , Joachim Eastwood , Jean-Christophe PLAGNIOL-VILLARD Date: Mon, 3 Dec 2012 14:01:30 +0000 In-Reply-To: <1354536914-6315-1-git-send-email-nicolas.ferre@atmel.com> References: <1354536914-6315-1-git-send-email-nicolas.ferre@atmel.com> Organization: Solarflare Communications Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.4-1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Originating-IP: [88.96.1.126] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2012-12-03 at 13:15 +0100, Nicolas Ferre wrote: > Depending on datapath, some revisions of GEM need > 64bits aligned descriptors. Use dmapool to allocate > these descriptors. > Note that different size between RX and TX rings > leads to the creation of two pools. > > Signed-off-by: Nicolas Ferre [...] dma_alloc_coherent() allocates whole pages, which I think is quite enough alignment. You can't save memory by doing this, since each pool needs at least one page. So what is this change meant to achieve? Ben. -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.