On Fri, Feb 2, 2018 at 5:40 PM, Doug Ledford <dledford@xxxxxxxxxx> wrote: > On Fri, 2018-02-02 at 16:07 +0000, Bart Van Assche wrote: >> On Fri, 2018-02-02 at 15:08 +0100, Roman Pen wrote: >> > Since the first version the following was changed: >> > >> > - Load-balancing and IO fail-over using multipath features were added. >> > - Major parts of the code were rewritten, simplified and overall code >> > size was reduced by a quarter. >> >> That is interesting to know, but what happened to the feedback that Sagi and >> I provided on v1? Has that feedback been addressed? See also >> https://www.spinics.net/lists/linux-rdma/msg47819.html and >> https://www.spinics.net/lists/linux-rdma/msg47879.html. >> >> Regarding multipath support: there are already two multipath implementations >> upstream (dm-mpath and the multipath implementation in the NVMe initiator). >> I'm not sure we want a third multipath implementation in the Linux kernel. > > There's more than that. There was also md-multipath, and smc-r includes > another version of multipath, plus I assume we support mptcp as well. > > But, to be fair, the different multipaths in this list serve different > purposes and I'm not sure they could all be generalized out and served > by a single multipath code. Although, fortunately, md-multipath is > deprecated, so no need to worry about it, and it is only dm-multipath > and nvme multipath that deal directly with block devices and assume > block semantics. If I read the cover letter right (and I haven't dug > into the code to confirm this), the ibtrs multipath has much more in > common with smc-r multipath, where it doesn't really assume a block > layer device sits on top of it, it's more of a pure network multipath, > which the implementation of smc-r is and mptcp would be too. I would > like to see a core RDMA multipath implementation soon that would > abstract out some of these multipath tasks, at least across RDMA links, > and that didn't have the current limitations (smc-r only supports RoCE > links, and it sounds like ibtrs only supports IB like links, but maybe > I'm wrong there, I haven't looked at the patches yet). Hi Doug, hi Bart, Thanks for your valuable input, here is my 2 cents: IBTRS multipath is indeed a network multipath, with sysfs interface to remove/add path dynamically. IBTRS is built on rdma-cm, so expect to support RoCE and iWARP, but we mainly tested in IB environment, slightly tested on RXE. Regards, -- Jack Wang Linux Kernel Developer -- 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
