From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC] [PATCH 0/3] ioat: DMA engine support Date: Thu, 24 Nov 2005 17:35:26 +0200 Message-ID: <4385DDBE.3040208@argo.co.il> References: <4384E7F2.2030508@pobox.com> <20051123223007.GA5921@wotan.suse.de> <20051124001700.GC14246@kvack.org> <20051124065037.GZ20775@brahms.suse.de> <4385DB32.7010605@argo.co.il> <20051124152924.GB5921@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Benjamin LaHaise , Jeff Garzik , Andrew Grover , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, john.ronciak@intel.com, christopher.leech@intel.com Return-path: To: Andi Kleen In-Reply-To: <20051124152924.GB5921@wotan.suse.de> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Andi Kleen wrote: >>> >>> >>As an example, an NFS server reads some data pages using iSCSI and sends >>them using NFS/TCP (or vice versa). >> >> > >For TX this can be done zero copy using a sendfile like setup. > > Yes, or with aio send for anonymous memory. >For RX it may help - but my point was that most applications >are not structured in this simple way. > > > Agreed. But those that do care, care very much. The data mover applications, simply because they don't touch the data, expect very high bandwidth. >>As long as they can be turned off. Not all usespace applications want to >>touch the data immediately. >> >> > >Perhaps. And lots of others might. Of course the simple >network benchmarks don't so the number on them look good. > > > There are very real non-benchmark applications that want this. >Just pointing out that it's not clear it will always be a big help. > > > Agree it should default to in-cache.