[openib-general] uVerbs and multiple cq_event support?

[Arlin Davis]

Hi Roland,

I have a question about uverbs cq_events. Currently, uverbs has one 
event (fd) handle that processes all CQ events. You mentioned earlier  
that you would possibly add support for more CQ events. Are you thinking 
one per CQ, or limiting to a small number like one per processor? If the 
thinking is NOT one per CQ then it may be somewhat restricitive to user 
applications that have multple connections with many CQs to process.

For instance, with uDAPL there are user wait objects (CQ_WAIT_OBJECT) 
that can be mapped directly to these CQ events. This enables the user 
thread to wait and wake up directly from the kernel CQ event processing 
which is very efficicent. However, this can only be done if verbs 
provides an event mechanism per CQ. Otherwise, I have to process the 
events in a separate thread and in turn process the user's event 
independent of the CQ event.

If the thinking is one per CQ then is fd's the way to go since we can 
have 1000's of CQs?

Comments?

Thanks,

-arlin