[openib-general] SA cache design

[Sean Hefty]

Rimmer, Todd wrote:
> While each process could do a GET_TABLE for all path records that
> would be rather inefficient and would provide 1,000,000 path records in
> the RMPP response, of which only 500 are of interest.

Each process could do a GET_TABLE for only those path records with the SGID set 
to their local port and NumPath set to 1.  This would give them only 1000 or so 
path records, most of which are of interest.

> Even if all 4000 processors were being used in a single run, each
> process only needs 3999 path records (999 or which are unique).
> In fact a given node will never need more than N or the N^2 path records
> because the remaining involve paths where this node is not involved.
> so getting all 1,000,000 path records would be very inefficient.

Even a local cache wouldn't get every possible path record.  The application 
should be no different.  An application that wants to connect to every node on 
the fabric should only need to issue a single path record query, all of which 
are of interest.

- Sean