[openib-general] Re: uverbs comp events

[Roland Dreier]

    Arlin> Yes, this is certainly another option; albeit one that
    Arlin> requires more system resources. Why not take full advantage
    Arlin> of the FD resource we already have? It's your call, but
    Arlin> uDAPL and other multi-thread applications could make good
    Arlin> use of a wakeup feature with these event interfaces. An
    Arlin> event model that allows users to create events and get
    Arlin> events but requires them to use side band mechanisms to
    Arlin> trigger the event seems incomplete to me.

I disagree.  Right now the CQ FD is a pretty clean concept: you read
CQ events out of it.  If you want to trigger a CQ event, then you
could post a work request to a QP that generates a completion event.
Adding a new system call for queuing synthetic events seems like
growing an ugly wart to me.

If we look at the analogous design of a multi-threaded network server,
where a thread might block waiting for input on a socket, we see that
there's no system call to inject synthetic data into a network socket.

I'd rather fix the uDAPL design instead of adding ugliness to the
kernel to work around it.

 - R.