> Quoting Dror Goldenberg <[EMAIL PROTECTED]>: > Subject: Re: [ofa-general] Re: Re: [PATCH RFC] sharing userspace IB objects > > Hal Rosenstock wrote: > >On Sun, 2007-07-01 at 15:05, Gleb Natapov wrote: > > > >>On Sun, Jul 01, 2007 at 07:27:24PM +0300, Dror Goldenberg wrote: > >> > >>>>SSQ is needed for scalability, no need to explain this (by > >>>>the way RD is needed for the same reason too. What's Mellanox > >>>>plan to support it? > >>>> > >>>RD is not supported in hardware today. Implementing RD is extremely > >>>complicated. To solve the scalability issues on MPI like applications > >>>we believe that SRC and SSQ are the right solutions. It is much simpler > >>>for implementation by both software and hardware. By MPI-like I refer > >>>to applications that have some level of trust between two processes of > >>>the > >>>same application. RD also has some performance issues as it only > >>>supports one message in the air. Those performance issues are solved > >>>by design in SRC/SSQ. > >>> > >>> > >>Didn't know about RD limitation. Is this shortcomings of IB spec or > >>general limitation of reliable datagram? RD looks much nice to me then > >>SRC/SSQ. > >> > > > >I think Dror is referring to number of messages in flight per EEC and > >number of messages in flight per QP being limited to 1 per IBA spec. > >Number of messages enqueued per EEC/QP is implementation dependent. > > > >-- Hal > > > Correct. The number of messages in flight per EEC is 1 per IB spec. > The fact that IB requires SQ WQEs to complete in order, even if their > destination is different EECs, makes it pretty challenging to have an > implementation that can really process more than one message > simultaneously per QP.
Hmm, I guess this requirement could easily be relaxed - in a way similiar to what was done for SRQ - without breaking applications. WRID is sufficient to identify the WR even without ordering guarantees. -- MST _______________________________________________ general mailing list [email protected] http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
