On Wed, 2019-07-17 at 09:55 -0400, Chuck Lever wrote: > Hi Trond- > > > On Jul 16, 2019, at 4:01 PM, Trond Myklebust <trondmy@xxxxxxxxx> > > wrote: > > > > Add a per-transport maximum limit in the socket case, and add > > helpers to allow the NFSv4 code to discover that limit. > > For RDMA, the number of credits is permitted to change during the > life > of the connection, so this is not a fixed limit for such transports. This is defining a maximum value, which is used for backchannel session slot negotiation. > > And, AFAICT, it's not necessary to know the transport's limit. The > lesser of the NFS backchannel and RPC/RDMA reverse credit limit will > be used. The server needs to know how many requests it can send in parallel on the back channel. If it sends too many, which it can and will do on TCP, then we currently break the connection, and so callbacks end up being dropped or missed altogether. -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx
