Hi Bart, Ursula, Dave, I am particularly concerned about SMC as address family. It should not be treated as address family, but rather an additional protocol similar for socket type SOCK_STREAM. While doing performance benchmarking last month and while porting few database application, I encountered a major hurdle where user space library heavily depend on AF_INET and AF_INET6 family through get_addrinfo and other friend functions. Adding or treating AF_SMC as AF_INET just doesn't sound right. Most user space code doesn't care for the protocol field, but do handle domain field. I personally believe it's not too late to modify SMC to drop expose AF_SMC and have it exposed through new protocol that can be exposed through socket() API. Parav > -----Original Message----- > From: linux-rdma-owner@xxxxxxxxxxxxxxx [mailto:linux-rdma- > owner@xxxxxxxxxxxxxxx] On Behalf Of Bart Van Assche > Sent: Monday, May 1, 2017 12:30 PM > To: hch@xxxxxx; davem@xxxxxxxxxxxxx; ubraun@xxxxxxxxxxxxxxxxxx > Cc: netdev@xxxxxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx > Subject: Re: net/smc and the RDMA core > > On Mon, 2017-05-01 at 18:33 +0200, Christoph Hellwig wrote: > > Hi Ursual, hi netdev reviewers, > > > > how did the smc protocol manage to get merged without any review 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 protocols > compare to each other from a performance point of view? If no performance > comparison between these protocols is available, shouldn't the performance > 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 = 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 library > 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.-- > To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body > of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at > http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
