From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: net/smc and the RDMA core Date: Mon, 1 May 2017 17:29:38 +0000 Message-ID: <1493659776.2665.7.camel@sandisk.com> References: <20170501163311.GA22209@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Cc: "netdev@vger.kernel.org" , "linux-rdma@vger.kernel.org" To: "hch@lst.de" , "davem@davemloft.net" , "ubraun@linux.vnet.ibm.com" Return-path: Received: from esa2.hgst.iphmx.com ([68.232.143.124]:22887 "EHLO esa2.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750839AbdEAR3l (ORCPT ); Mon, 1 May 2017 13:29:41 -0400 In-Reply-To: <20170501163311.GA22209@lst.de> Content-Language: en-US Content-ID: Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2017-05-01 at 18:33 +0200, Christoph Hellwig wrote: > Hi Ursual, hi netdev reviewers, >=20 > how did the smc protocol manage to get merged without any review=20 > on linux-rdma at all? As the results it seems it's very substandard > in terms of RDMA API usage, e.g. it neither uses the proper CQ API > nor the RDMA R/W API, and other will probably find additional issues > as well. Hello Dave and Ursula, It seems very rude to me to have merged the SMC protocol driver without having involved the linux-rdma community. Anyway, I have the following questions for Dave and Ursula: * Since the Linux kernel is standards based: where can we find the standard that defines the SMC wire protocol? If this protocol has not been standardized yet: in what file (other than *.[ch]) in the Linux kernel tree has this protocol been documented? * What are the differences between the SMC protocol, the SDP protocol and the rsockets protocol? How do existing implementations for these protocol= s compare to each other from a performance point of view? If no performance comparison between these protocols is available, shouldn't the performanc= e of these protocols have been compared with each other before a review of the SMC driver even started? * What are the reasons why the SDP driver was never accepted upstream? Do the arguments why SDP was not accepted upstream also apply to the SMC driver (SDP =3D Sockets Direct Protocol)? * Since SMC has to be selected by specifying AF_SMC, how are users expected to specify whether AF_INET, AF_INET6 or yet another address family should be used to set up a connection between SMC endpoints? * Is the SMC driver limited to RoCE? Are you aware that the rsockets librar= y supports multiple transport layers (RoCE, IB and iWARP)? * Since functionality that is similar what the SMC driver provides already exists in user space (rsockets), why has this functionality been reimplemented as a kernel driver (SMC)? Bart.=