SMB Direct Implementation via Linux Device Driver for Samba Design Doc, final?

[Or Gerlitz]

On 26/08/2013 10:42, Stefan (metze) Metzmacher wrote:
>> >Another approach would be to have a single process responsible for all RDMA
>> >handling and have the smbd's communicate with that process about new incoming
>> >connections and reads and writes. While this would work, and could eliminate
>> >multiple copies of the data with shared memory, it would involve a context
>> >switch for most if not all RDMA transfers.
> Only reason for doing this would be research how the protocol works...
>

Yes, this is possible too. AFAIK, there another cluster file system rdma 
implementation which uses
this practice, of daemon process  which handle RDMA and uses 
shared-memory with other processes.

In that respect, I am not sure to follow your comment on "could 
eliminate multiple copies of the data with shared
memory" as I understood the design document you have sent, the intention 
is to allocate memory in the kernel
rdma char-device which will be

1) used for send/recv/rdma
2) mmap-ed to user space

So where are the copies in this design?

As for "involve a contextswitch for most if not all RDMA transfers", 
indeed, in this architecture you
will have contextswitch between the rdma daemon to the worker processes 
vs. user/kernel mode switch
when you have each worker opening the rdma char-device.

Or.