On Wed, 2006-02-08 at 23:20 -0800, Sean Hefty wrote: > >Hmm. Can you put a number on how much better RDMA write with > >immediate is on current HCA hardware? How does using the underlying > >OpenIB verbs ability to post a list of work requests compare (ie > >posting an RDMA write followed by a send in one verbs call)? > >Maybe "post multiple" is a better direction for DAT. > > A "post multiple" call as a general API makes sense, but I think that's a > separate issue. > > Given that IB provides true immediate data with RDMA writes, a way should be > available to make use of it. I don't know what the performance numbers > between > using a write with immediate versus a write followed by a send, but I don't > think that anyone could argue that the write with immediate wouldn't perform > better. > > To me, the question is whether write with immediate is supported as a > transport > specific extension, which was Arlin's original patch, or through some standard > API. The attempt to make the API standard, so that iWarp could emulate it > (poorly in my view), is what appears to be driving the disagreements. > > It also appears to me that the decisions are coming down to one of the > following. If iWarp can emulate write with immediate, then a generic API > should > be used.
This opens Pandora's box. Should iWARP also emulate ATOMICs? Which should be emulated and which should not ... What are the criteria for deciding? > If iWarp cannot properly emulate write with immediate, then the API > should be transport specific. It should be transport specific because it is a transport specific feature. Although -- in this case -- it could but implemented in iWARP in my view it _should_ not. > It's curious to me that in both cases, iWarp is > driving the API decision and design for something that is an IB specific > feature. Huh? > > - Sean > > > _______________________________________________ > openib-general mailing list > openib-general@openib.org > http://openib.org/mailman/listinfo/openib-general > > To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general _______________________________________________ openib-general mailing list openib-general@openib.org http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general