Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756750AbXHVHl0 (ORCPT ); Wed, 22 Aug 2007 03:41:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752794AbXHVHlS (ORCPT ); Wed, 22 Aug 2007 03:41:18 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:55659 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751454AbXHVHlR (ORCPT ); Wed, 22 Aug 2007 03:41:17 -0400 Message-ID: <46CBE838.4000302@sgi.com> Date: Wed, 22 Aug 2007 09:39:36 +0200 From: Jes Sorensen User-Agent: Thunderbird 2.0.0.0 (X11/20070719) MIME-Version: 1.0 To: James Bottomley Cc: akepner@sgi.com, Randy Dunlap , linux-kernel , rdreier@cisco.com, linux-ia64 Subject: Re: [PATCH 2/3] dma: override "dma_flags_set_dmaflush" for sn-ia64 References: <20070818002746.GU1813@sgi.com> <46C94FD5.6000006@sgi.com> <20070821193522.GD5592@sgi.com> <20070821130515.6e745b17.randy.dunlap@oracle.com> <1187729729.18410.48.camel@localhost.localdomain> <20070822003450.GM5592@sgi.com> <1187745249.18410.67.camel@localhost.localdomain> In-Reply-To: <1187745249.18410.67.camel@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1081 Lines: 27 James Bottomley wrote: > On Tue, 2007-08-21 at 17:34 -0700, akepner@sgi.com wrote: >> The term "posted DMA" is used to describe this behavior in the Altix >> Device Driver Writer's Guide, but it may be confusing things here. >> Maybe a better term will suggest itself if I can clarify.... > > OK, but posted DMA has a pretty specific meaning in terms of PCI, hence > the confusion. Maybe it would be more better to refer to this as 'out of order DMA'? >> On Altix, DMA from a device isn't guaranteed to arrive in host memory >> in the order it was sent from the device. This reordering can happen >> in the NUMA interconnect (it's specifically not a PCI reordering.) > > This is mmiowb and read_relaxed() again, isn't it? I believe it's the same problem, except this time it's when exposing structures to userland. Cheers, Jes - 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/