From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roland Dreier Subject: Re: [ofa-general] Re: [PATCH RFC] RDMA/CMA: Allocate PS_TCP ports from the host TCP port space. Date: Fri, 17 Aug 2007 12:52:39 -0700 Message-ID: References: <46C310E1.7020503@opengridcomputing.com> <46C3B5EF.5060409@garzik.org> <1187271791.4685.9.camel@trinity.ogc.int> <20070816.141751.115907875.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: jeff@garzik.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, general@lists.openfabrics.org To: David Miller Return-path: In-Reply-To: <20070816.141751.115907875.davem@davemloft.net> (David Miller's message of "Thu, 16 Aug 2007 14:17:51 -0700 (PDT)") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: general-bounces@lists.openfabrics.org Errors-To: general-bounces@lists.openfabrics.org List-Id: netdev.vger.kernel.org > > Isn't RDMA _part_ of the "software net stack" within Linux? > It very much is not so. This is just nit-picking. You can draw the boundary of the "software net stack" wherever you want, but I think Sean's point was just that RDMA drivers already are part of Linux, and we all want them to get better. > When using RDMA you lose the capability to do packet shaping, > classification, and all the other wonderful networking facilities > you've grown to love and use over the years. Same thing with TSO and LRO and who knows what else. I know you're going to make a distinction between "stateless" and "stateful" offloads, but really it's just an arbitrary distinction between things you like and things you don't. > Imagine if you didn't know any of this, you purchase and begin to > deploy a huge piece of RDMA infrastructure, you then get the mandate > from IT that you need to add firewalling on the RDMA connections at > the host level, and "oh shit" you can't? It's ironic that you bring up firewalling. I've had vendors of iWARP hardware tell me they would *love* to work with the community to make firewalling work better for RDMA connections. But instead we get the catch-22 of your changing arguments -- first, you won't even consider changes that might help RDMA work better in the name of maintainability; then you have to protect poor, ignorant users from accidentally using RDMA because of some problem or another; and then when someone tries to fix some of the problems you mention, it's back to step one. Obviously some decisions have been prejudged here, so I guess this moves to the realm of politics. I have plenty of interesting technical stuff, so I'll leave it to the people with a horse in the race to find ways to twist your arm. - R.