[openib-general] [RFC] [PATCH] user_mad: Support RMPP on send side

[Hal Rosenstock]

On Wed, 2005-05-11 at 17:37, Sean Hefty wrote:
> Hal Rosenstock wrote:
> > A couple of notes on this patch:
> > 1. send side copying
> > There are currently 2 copies from user space done even in the non RMPP
> > case. It would be nice to reduce that to one in the non RMPP case.
> > This is an optimization to add at some point.
> 
> Having a single data copy on both the send side and receive side should be 
> possible without too much work.  I know that the receive side copies twice 
> now, but sends are one.  Why not keep it this way, versus having to come 
> back, modify the code again, and retest?

The main issue I see on the send side is that without examining the
header, one can't get all the parameters for ib_create_send_mad. Even
with some variant of this call (perhaps broken up into 2 parts), I think
the mad_agent is the key parameter needed. I don't see a way to get this
ahead of time without 2 copies. Am I then back to not using this routine
and doing it "by hand" ?

-- Hal