From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: net/smc and the RDMA core Date: Tue, 2 May 2017 18:39:20 +0000 Message-ID: <1493750358.2552.13.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 Return-path: In-Reply-To: Content-Language: en-US Content-ID: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "hch-jcswGhMUV9g@public.gmane.org" , "davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org" , "ubraun-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org" Cc: "netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-rdma@vger.kernel.org On Tue, 2017-05-02 at 14:25 +0200, Ursula Braun wrote: > if you can point out specific issues, we will be happy to work with you > to get them addressed! Hello Ursula, My list of issues that I would like to see addressed can be found below. Do= ug, Christoph and others may have additional inputs. The issues that have not y= et been mentioned in other e-mails are: - The SMC driver only supports one RDMA transport type (RoCE v1) but =A0 none of the other RDMA transport types (RoCE v2, IB and iWARP). New =A0 RDMA drivers should support all RDMA transport types transparently. The traditional approach to support multiple RDMA transport types is by using the RDMA/CM to establish connections. - The implementation of the SMC driver only supports RoCEv1. This is =A0 a very unfortunate choice because: =A0 - RoCEv1 is not routable and hence is limited to a single Ethernet =A0=A0=A0=A0broadcast domain. =A0 - RoCEv1 packets escape a whole bunch of mechanisms that only work =A0=A0=A0=A0for IP packets. Firewalls pass all RoCEv1 packets and switches =A0=A0=A0=A0do not restrict RoCEv1 packets to a single VLAN. This means tha= t =A0=A0=A0=A0if the network configuration is changed after an SMC connection =A0=A0=A0=A0has been set up such that IP communication between the endpoint= s =A0=A0=A0=A0of an SMC connection is blocked that the SMC RoCEv1 packets wil= l not be blocked by the network equipment of which the configuration =A0=A0=A0=A0has just been changed. - As already mentioned by Christoph, the SMC implementation uses RDMA calls that probably will be deprecated soon (ib_create_cq()) and should use the RDMA R/W API instead of building sge lists itself. Bart.= -- 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