[openib-general] ib_mad.h ib_mad_post_send questions and a minor commentary change

[Hal Rosenstock]

On Mon, 2004-09-06 at 18:36, Roland Dreier wrote:
>     Hal> That seems fine when the WRs are not linked. What happens
>     Hal> when they are linked and there is some error on one of the
>     Hal> linked WRs ? In that case, some send WRs get posted and
>     Hal> others do not. Does there need to be another parameter
>     Hal> indicating how far in the list was posted so the ib_mad
>     Hal> client knows what to repost ? I don't think that all errors
>     Hal> can be hidden from the ib_mad client.
> 
> I guess we should add a parameter like 'struct ib_send_mad_wr **bad_wr'
> to match the way that ib_post_send() is defined...

Thanks for pointing that out. I had missed that (the fact that this API
was different from ib_post_send). Patch for this to follow shortly...

>     Hal> Also, if this were to occur in the middle of an RMPP
>     Hal> transaction, should this be detected and any special actions
>     Hal> taken ? Or would this just rely on normal RMPP handling at
>     Hal> the other end to detect any issues ?
> 
> There's no reason for a send request to fail in normal operation, so I
> don't see much that the MAD layer can try to do to recover.

Yes, but there are a number of errors which can occur (not just the 
posting of the send failing) as more information needs tracking per send
so that there is some memory allocation involved too which can fail.

> In any case, I'd like to see some real code that actually can be used, at
> least in the normal case as soon as possible.  So I would suggest
> deferring secondary issues like this until after we have a working
> implementation.

I get the message :-( Sorry this is taking longer than I had projected.
We can discuss the "schedule" and how to transition on Thursday.

I will focus on the "normal" code path and leave comments on what else
needs to be filled in/addressed in a subsequent pass.

>     Hal> I also have a related implementation question. The ib_mad
>     Hal> client supplies wr_id in the send WR. If it turns out that it
>     Hal> might be better to use wr_ids in some special encoded way, is
>     Hal> it acceptable to do that as long as the client wr_id is
>     Hal> returned in the send WC ?
> 
> I don't see any reason why not.  Do you see any problems?

No problems but rather I was wondering about whether there would be any
asthetic objections.

-- Hal