[openib-general] Some Missing Features from mthca/userMADaccess

[Sean Hefty]

shaharf wrote:
> 
> [SHAHAR] Attributes filtering can be done with O(1). First you don't
> have to support the entire theoretical range. Currently less then
> 256 attributes are used per class.

You can't make this assumption for vendor defined classes.

> But even more important then that, what is the use
> for methods filtering?

It should allow creation of a trap handler, or other more modular code. 
  If there are no clients using method filtering, then I'm all for 
removing it.

>  Do you see a way to handle the different SA client registrations
> for events (InformInfo) where an incoming Report could go to
> multiple clients with the current approach ?

I think that more complex filtering should be done above the MAD layer.

The purpose of the snoop functionality is to let a client register to 
view all MADs and then apply their own filter on which MADs they want 
to make a copy of.  This is more flexible than any API that we could 
define that tried to do the filtering in the MAD layer, and I believe 
is sufficient for kernel-mode clients.

For user-mode clients, I would recommend that the snooping be done in 
the kernel for performance reasons.  There would need to be a yet to be 
defined API defined for user-mode clients to set the snooping parameters.

I think a reasonable API would be to let user's specify a mask over the 
entire MAD (or at least the header).