Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752837AbaFMPrc (ORCPT ); Fri, 13 Jun 2014 11:47:32 -0400 Received: from qmta06.emeryville.ca.mail.comcast.net ([76.96.30.56]:52418 "EHLO qmta06.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751283AbaFMPra (ORCPT ); Fri, 13 Jun 2014 11:47:30 -0400 Date: Fri, 13 Jun 2014 10:47:27 -0500 (CDT) From: Christoph Lameter To: David Rientjes cc: Luiz Capitulino , Yinghai Lu , Tejun Heo , Andrew Morton , Andi Kleen , Rik van Riel , Yasuaki Ishimatsu , Linux MM , Linux Kernel Mailing List , "stable@vger.kernel.org" Subject: Re: [PATCH] x86: numa: drop ZONE_ALIGN In-Reply-To: Message-ID: References: <20140608181436.17de69ac@redhat.com> <20140609150353.75eff02b@redhat.com> <20140611092337.35794bc0@redhat.com> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 11 Jun 2014, David Rientjes wrote: > > > Yes, but the question is: why? > > > > zones need to be aligned so that the huge pages order and other page > > orders allocated from the page allocator are at their "natural alignment". > > Otherwise huge pages cannot be mapped properly and various I/O devices > > may encounter issues if they rely on the natural alignment. > > > > Any reason not to align to HUGETLB_PAGE_ORDER on x86 instead of > ZONE_ALIGN? if MAX_ORDER = Hugetlb order then no issue. However, if there are devices that require larger order pages (dont know if such devices exist) then there may be an issue. SGI UV DMA engine, graphics or some other device? -- 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/