From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Graf Subject: Re: Checksum offload queries Date: Wed, 9 Dec 2015 23:21:53 +0100 Message-ID: <20151209222153.GE11201@pox.localdomain> References: <5665A848.9010001@solarflare.com> <20151207.143848.2158761076110518741.davem@davemloft.net> <5666EC4B.40800@solarflare.com> <20151208.120654.2127200076257822677.davem@davemloft.net> <56681B18.3030200@solarflare.com> <566864C0.6020204@solarflare.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Edward Cree , Linux Kernel Network Developers , David Miller To: Tom Herbert Return-path: Received: from mail-wm0-f44.google.com ([74.125.82.44]:33727 "EHLO mail-wm0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751422AbbLIWVz (ORCPT ); Wed, 9 Dec 2015 17:21:55 -0500 Received: by mail-wm0-f44.google.com with SMTP id c201so6478694wme.0 for ; Wed, 09 Dec 2015 14:21:55 -0800 (PST) Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 12/09/15 at 10:00am, Tom Herbert wrote: > On Wed, Dec 9, 2015 at 9:28 AM, Edward Cree wrote: > > Which only pushes the problem onto when someone wants to nest > > encapsulations. (I heard you like tunnels, so I put a tunnel in your > > tunnel so you can encapsulate while you encapsulate.) > > Or to put it another way, 2 isn't a number; the only numbers are 0, 1 > > and infinity ;) > > Perhaps in practice 2 csums would be enough, for now. But isn't the > > whole point of the brave new world of generic checksums that it should > > be future-proof? > > > If there is a need then we can add an arbitrary number. But no one has > proven there is a need, however we do have a real need for checksum > offload outside of the narrow uses of NETIF_F_IP[V6]_CSUM. Need may be a strong word here but people have started doing nested tunneling by running container orchestration tools which use VXLAN to isolate containers inside of OpenStack virtual infrastructure which also creates virtual networks. I'm not saying it's sane or desirable but we will start seeing nested tunnels in the wild :-(