Re: FW: [PATCH for 2.6.25] SVCRDMA: Use only 1 RDMA read scatter entry for iWARP adapters

[Roland Dreier <rdreier-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>]

 > Will do, thanks, but, as a subsequent patch, could we clean this up a
 > little?  For example, assuming sge_count and sc_max_sge are always
 > positive, isn't the (sge_count > 1) check superfluous, given that the
 > following min_t's going to produce 1 in that case anyway?

Yes, I had the same thought reading the code but I didn't want to try
and do too many things in one patch.

 > Also, would it be possible just to ensure sc_max_sge is just set to 1
 > from the start in this case?

I think the problem with this is that on InfiniBand, it is fine to
have multiple scatter entries for an RDMA read request, while on iWARP
only 1 scatter entry is possible for RDMA read.  For both IB and
iWARP, you can eg have multiple gather entries for an RDMA write.  So
sc_max_sge as it stands may want to be bigger than 1 even for iWARP devices.

One not-too-bad possibility would just be to have sc_max_sge and
sc_max_sge_rdma_read fields and initialize them properly based on IB
vs iWARP...

 - R.