multiplexing TCP sockets in the NFS client

[Scott Long]

Rick Macklem wrote:
> Long long ago, I felt it might be better to use a separate TCP socket
> for each mount to the same server. The argument was along the lines of:
> 
>     Some mounts might be much busier than others and, as such, the
>     separate TCP socket would provide feedback to the client w.r.t.
>     load on that mount. The assumption w.r.t. busier mount points
>     tacitly assumed separate disks with some disks experiencing
>     heavy I/O loads.
> 
> It seems to me that these days, what with SANs, RAIDs, GEOM,... that a
> mount point probably isn't going to reflect a different disk subsystem
> so much as an administrative boundary. Also, it's not obvious that the
> feedback argument is relevant anyhow, since clients will still receive
> replies when the server gets around to doing the RPC, in any case.
> 
> So, I'm thinking that it might be better to change the client code so that
> it shares one TCP connection between all mounts to the same server. This
> reduces the number of TCP connections (possibly an issue if clients use
> an automounter to do a lot of mounts). It might also help w.r.t transport
> performance by increasing the volume of data being transferred on the TCP
> connection? (I don't know enough about current TCP stacks to know if this
> is the case or not?)
> 
> Any comments? rick
> 

Is SCTP of any interest in the NFS world?

Scott