On 10/15/2012 4:07 AM, Yann Droneaud wrote:
Le lundi 15 octobre 2012 à 10:27 +0200, Stefan (metze) Metzmacher a
écrit :
Hi,
I'm currently researching how to implement SMBDirect [MS-SMBD]
together with the multi channel feature of SMB 3.0 in Samba.
As Samba currently uses one process per tcp connection
and maintains a lot of in memory state within the process
(e.g. for the SMB_VFS modules) it would require a lot of work
to change Samba to coordinate two (or more) processes for one logical
multi channel connection.
My current plan tries to pass the socket fd of new connections
(which join an existing multi channel session) via fd-passing to
the existing process.
Now I'm wondering if this would also be possible with
a rdma connection (struct rdma_cm_i ).
RDMA / verbs ressources are tied to a process (especially Memory
Registration), but it's ending up in the HCA, which is probably unaware
of processes.
Additionally, an RDMA_CM connection is not identified by a FD, so this
kind of Unix trick (FD passing through Unix socket: SCM_RIGHTS) is not
going to work.
Forking might already be a challenge for a RDMA/verbs application, so I
don't think that sharing/moving an RDMA_CM connection across different
processes is supported.
But other people on this list (especially Roland Dreier and Sean Hefty)
could find a solution.
Regards.
fork() support like you need is not there in Linux RDMA verbs. Another
alternative is to fork() before you setup the RDMA connection. IE if a
regular TCP socket is first used to negotiate RDMA mode, then maybe you
could fork() after negotiation but before setting up the RDMA connection
and other resources?
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