From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Steve Wise" Subject: RE: [PATCH v3 03/13] Attach/detach SoftiWarp to/from network and RDMA subsystem Date: Tue, 23 Jan 2018 11:55:16 -0600 Message-ID: <014c01d39473$536ba5f0$fa42f1d0$@opengridcomputing.com> References: <20180114223603.19961-1-bmt@zurich.ibm.com> <20180114223603.19961-4-bmt@zurich.ibm.com> <00ff01d39467$f1f31b60$d5d95220$@opengridcomputing.com> <20180123164316.GC30670@ziepe.ca> <011801d3946b$53ef0060$fbcd0120$@opengridcomputing.com> <20180123170517.GE30670@ziepe.ca> <013a01d3946f$034683f0$09d38bd0$@opengridcomputing.com> <20180123172830.GF30670@ziepe.ca> <014501d39471$84cdee20$8e69ca60$@opengridcomputing.com> <20180123174758.GH30670@ziepe.ca> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180123174758.GH30670-uk2M96/98Pc@public.gmane.org> Content-Language: en-us Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: 'Jason Gunthorpe' Cc: 'Bernard Metzler' , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org > > On Tue, Jan 23, 2018 at 11:42:20AM -0600, Steve Wise wrote: > > > Since the iwarp protocols run on top of TCP/IP, there is always the case > > that some middle box resegments tcp segments differently, so a good iwarp > HW > > implementation should deal with funny alignments, partial iWARP PDUs > > arriving, etc. But the RFCs, as I read them, want implementations to try > > "really hard" to avoid spanning an iWARP PDU across many TCP segments. > And > > I think siw should do the same, by default. > > But Bernard just said siw doesn't interoperate in certain cases > because of this - so that sounds like more than 'try really hard' ?? > > Or is that an overstatement and it just makes the rx side slower if > segmentation is not optimal? Creating 64K iWARP PDUs causes interoperability problems. If siw builds iWARP PDUs that fit within the TCP wire MSS, then these problems are avoided, and siw becomes more spec compliant. If the iWARP PDUs are built this way, then nothing the tcp stack does will cause problems other than slow down things. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html