[openib-general] CMA service ID space versus private data bytes

[Sean Hefty]

There's a trade-off between service ID space used by the CMA and the amount of 
private data available to the user.  Currently, the CMA reserves 64k of service 
ID space and provides 56 bytes of user private data.  We can give the user 60 
bytes of private data space by shifting 3 bytes (plus 1 reserved byte) from the 
private data into the service ID.  This results in the CMA reserving 2^40 IDs 
(about 6% of the total range).  How important is the private data to people 
versus the conservation of service IDs?

- Sean