On 05/01/2017 07:29 PM, Bart Van Assche wrote: > 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? Hello Bart, The protocol is standardized, see: http://www.rfc-editor.org/info/rfc7609. I described this and some more protocol details in my patch series overview mail, see for instance: http://marc.info/?l=linux-s390&m=148397751211964&w=2 This description explains the reasons to come up with SMC-R. > * 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? The IPv6 support in SMC-R is on our todo-list. > * Is the SMC driver limited to RoCE? Are you aware that the rsockets library > supports multiple transport layers (RoCE, IB and iWARP)? For now, only RoCE is supported. Other transports might be added in the future. > * 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. > Regards, Ursula -- 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
