On Thu, 2007-10-11 at 12:39 -0500, Steve Wise wrote: > Doug Ledford wrote: > > So, one of the options when creating a QP is the max inline data size. > > If I understand this correctly, for any send up to that size, the > > payload of that send will be transmitted to the receiving side along > > with the request to send. > > What it really means is the payload is DMA'd to the HW on the local side > in the work request itself as opposed being DMA'd down in a 2nd > transaction after the WR is DMA'd and processed. It has no end-to-end > significance. Other than to reduce the latency needed to transfer the data.
OK, that clears things up for me ;-)
> > This reduces back and forth packet counts on
> > the wire in the case that the receiving side is good to go, because it
> > basically just responds with "OK, got it" and you're done.
>
> I don't think this is true. Definitely not with iWARP. INLINE is just
> an optimization to push small amts of data downto the local adapter as
> part of the work request, thus avoiding 2 DMA's.
> Even though you create the QP with the inline option, only WRs that pass
> in the IBV_SEND_INLINE flag will do inline processing, so you can
> control this functionality at a per-WR basis.
Hmm..that raises a question on my part. You don't call ibv_reg_mr on
the wr itself, so if the data is pushed with the wr, do you still need
to call ibv_reg_mr on the data separately?
--
Doug Ledford <[EMAIL PROTECTED]>
GPG KeyID: CFBFF194
http://people.redhat.com/dledford
Infiniband specific RPMs available at
http://people.redhat.com/dledford/Infiniband
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