Return-Path: Received: from caramon.arm.linux.org.uk ([78.32.30.218]:48208 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751815Ab1AFSFr (ORCPT ); Thu, 6 Jan 2011 13:05:47 -0500 Date: Thu, 6 Jan 2011 18:05:30 +0000 From: Russell King - ARM Linux To: James Bottomley Cc: Trond Myklebust , Linus Torvalds , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, Marc Kleine-Budde , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Marc Kleine-Budde , linux-arm-kernel@lists.infradead.org, Parisc List , linux-arch@vger.kernel.org Subject: Re: still nfs problems [Was: Linux 2.6.37-rc8] Message-ID: <20110106180530.GI31708@n2100.arm.linux.org.uk> References: <20110105200008.GJ8638@n2100.arm.linux.org.uk> <1294259637.16957.25.camel@mulgrave.site> <20110105210448.GM8638@n2100.arm.linux.org.uk> <1294262208.2952.4.camel@heimdal.trondhjem.org> <1294268808.2952.18.camel@heimdal.trondhjem.org> <1294270104.16957.73.camel@mulgrave.site> <1294335614.22825.154.camel@mulgrave.site> Content-Type: text/plain; charset=us-ascii In-Reply-To: <1294335614.22825.154.camel@mulgrave.site> Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Thu, Jan 06, 2011 at 11:40:13AM -0600, James Bottomley wrote: > On Wed, 2011-01-05 at 23:28 +0000, James Bottomley wrote: > > Can you explain how the code works? it looks to me like you read the xdr > > stuff through the vmap region then write it out directly to the pages? > > OK, I think I see how this is supposed to work: It's a sequential loop > of reading in via the pages (i.e. through the kernel mapping) and then > updating those pages via the vmap. In which case, I think this patch is > what you need. > > The theory of operation is that the readdir on pages actually uses the > network DMA operations to perform, so when it's finished, the underlying What network DMA operations - what if your NIC doesn't do DMA because it's an SMSC device?