[openib-general] Re:[ULP] how to choose appropriate ULPs for application

[James Lentini]

On Wed, 13 Jul 2005, Michael Krause wrote:

> At 06:39 AM 7/13/2005, James Lentini wrote:
>> 
>> kDAPL was designed specifically for RDMA networks with lots of features 
>> that allow you to control how the network is used. This is good if you are 
>> writing new code, but means that old code needs substantial porting.
>
> Ideally, applications stay out of such decisions.  Middleware's job is to 
> handle application optimization, etc. so that the end consumer stays as 
> ignorant as possible thus focused on their application's needs not the 
> networks.  The middleware API - whether DAPL, IT API, RNIC PI, whatever - can 
> provide the hooks needed to manage the usage from a given endnode's 
> perspective.  But even here, the real network management, what routes are 
> actually used, the arbitration for QoS, etc. should also be outside of the 
> middleware's control.  It simply manages a set of local resources and allows 
> the fabric management to do the rest.  There is more to this than that but 
> that is how IB was constructed which is no different in many respects from 
> how IP works as well.

Let me clarify: kDAPL users can specify exactly how data is transfered 
(SEND, RDMA write, RDMA read), completion events are processed, memory 
is registered, etc. This is the "network control" I was referring to. 
In retrospect, it would be more correct refer to this as "adapter 
control".