[rds-devel] [ofa-general] [RFC] dropping RDS over TCP support

[Richard Frank]

Yes, RDS is a socket provider - regardless of which RDS transport plug 
in it is running over.  RDS is structured to run over any transport 
plug-in that provides reliable connection semantics. Today, we have two 
plug-ins (logically 3 plugins) - IB, IWARP, TCP..
 
As a socket provider - RDS is a networking driver - no getting around 
that - as I recall this was the thinking behind putting RDS in /net..

I suppose the rdma transport plug-ins for RDS could live in rdma part of 
the tree - but it's probably easier to maintain with the current layout 
- where everything associated with RDS is kept together.

Perhaps the real question is - does RDS running over TCP offer valuable 
functionality - enough to balance the cost of maintaining it ?
I believe the answer is yes - as it allows running RDS over standard 
ethernet NICS like GE and 10GE - but we need to get some data to prove 
this.

Perhaps we should work on getting performance data to validate RDS/TCP 
as a solution over 10GE.

Or Gerlitz wrote:
> Richard Frank wrote:
>> So by this logic IPOIB is an rdma driver - since it lives in the 
>> drivers/infiniband ?
> Yes, as Roland commented in the past, every IB driver has two souls... 
> for example IPoIB is a network driver and IB driver, SRP is a SCSI LLD 
> and IB driver, iSER is an IB driver, a SCSI LLD and an iSCSI trasport 
> provider, etc etc. The point is that IB/RDMA is special enough for it 
> to have its own code location and maintainer in the mainline kernel.
>
>> I'm still not following why we differentiate if the driver is net vs 
>> rdma - by whether or not the driver uses the TCP transport.. ?
> RDS is a socket provider and if this socket has also implementation 
> over tcp/stream sockets it sounds like its --core-- code belong to the 
> net section of the code base.
>
>> What about other kernel modules that use network TCP transport - are 
>> they all network drivers ?
> no. For example iscs/tcp uses TCP sockets and is under drivers/scsi
>
> Or
>