[openib-general] ib_mad.h rmpp_version and RRespTime in header

[Hal Rosenstock]

On Thu, 2004-08-05 at 17:12, Sean Hefty wrote:
> On Thu, 05 Aug 2004 16:52:33 -0400
> Hal Rosenstock <halr at voltaire.com> wrote:
> 
> > I'm confused. I thought the sender was just sending
> > (ib_mad_post_send_msg) a buffer of some length (indicated in
> > ib_mad_msg). Wouldn't RMPP take that and fragment it and add
> > the headers ? Is there another call/structures yet to be added 
> > for this ?
> 
> I'm assuming that the headers are provided by the user, and that the user has set the data in the headers correctly.  I'm picturing an RMPP implementation that would do one of two things:

Yes, I can see from your latest proposed changes.

> 1. Update the header and post a send_wr consisting of at most 2 sg-entries.  The first sg-entry would reference the MAD header, the second the data portion.  After the send_wr completes, the header would be updated, and the next segment would be transfered.  This method allows zero-copy sends.
> 
> 2. Allocate an array of MAD headers.  Copy the existing MAD header into each slot, then update each header based on its segment number.  Post send_wr's with 2 sg-entries each.  Each send_wr would reference one of the headers, plus the corresponding data.  This method allows sending multiple packets at once.
> 
> I like the first method myself.

1 would need to be done per segment whereas 2 could get a window's worth
of segments out at once. 1 is simpler to implement. 2 seems more
efficient in terms of RMPP but more complex to implement. 

-- Hal