[openib-general] [RFC] libibverbs completion event handling

[Roland Dreier]

    Caitlin> I'm not sure I follow what a "completion channel" is.  My
    Caitlin> understanding is that work completions are stored in
    Caitlin> user-accessible memory (typically a ring buffer). This
    Caitlin> enables fast-path reaping of work completions. The OS has
    Caitlin> no involvement unless notifications are enabled.

Right.  Notifications ("events" in the terminology I used) are the
only thing I was talking about.

    Caitlin> The "completion vector" is used to report completion
    Caitlin> notifications. So is the completion vector a *single*
    Caitlin> resource used by the driver/verbs to report completions,
    Caitlin> where said notifications are then split into user context
    Caitlin> dependent "completion channels"?

Yes.

    Caitlin> The RDMAC verbs did not define callbacks to userspace at
    Caitlin> all. Instead it is assumed that the proxy for user mode
    Caitlin> services will receive the callbacks, and how it relays
    Caitlin> those notifications to userspace is outside the scope of
    Caitlin> the verbs.

That "outside the scope" part is exactly what I'm talking about
implementing here.

 - R.