[openib-general] Some ib_mad.h Redirection Comments

[Sean Hefty]

On Sat, 7 Aug 2004 01:09:58 +0300
"Yaron Haviv" <yaronh at voltaire.com> wrote:

> I think Hal is focused on the Request side any Sean on the Response
> (Server) side 
> I'm not sure there is argument that the Server side owns the QP's (other
> than QP1 owned by the GSI)

I'm focused on both sides.  I'm just not sure that whatever is done on the request side necessarily changes the API.  If we're in agreement on the server side, then I think we're more than half-way there.
 
> I don't see what is the value in having every potential GSI client
> implement a common functionality of identifying it's a Redirect, and
> resending the request to the new location, why not just have the GSI
> layer do that common functionality for all the consumers ?
> I think it is also trivial for the GSI to implement such functionality 

My general thought is that if something is trivial to implement, just push it up to the clients.  However, I'm not sure that redirection is that simple.  With a 1000 node fabric, 3 services per node, and everyone redirecting, the redirecting table will be substantial.  I need to think about this more and continue discussing it, but I'm becoming convinced that there may be enough work there to justify moving some of this into the access layer.
 
> If your main concern is CM (that has a single client per node, multiple
> remote servers, and some different behavior) we can treat it as an
> exception, I'm more focused at things such as distributed SA in such
> cases we can cache/lookup based on a class first 

I pick the CM because it's the simplest type of client.  It doesn't use RMPP or request/response transfers.  I think starting with the CM will ensure that we get the right layering of services.