On 22 Feb 2006 17:01:43 -0500, Hal Rosenstock <[EMAIL PROTECTED]> wrote: > On Wed, 2006-02-22 at 12:53, Fabian Tillier wrote: > > On 2/22/06, Greg Lindahl <[EMAIL PROTECTED]> wrote: > > > > > > On Tue, Feb 21, 2006 at 11:40:53PM -0800, Fabian Tillier wrote: > > > > > > > You'd have to make the group 1X. Note that the group being 1X doesn't > > > > limit unicast traffic to 1X rates, since the rate for unicast traffic > > > > would be set based on the rate reported in the path records for the > > > > various endpoints. > > > > > > > > So 4X SDR and 4X DDR nodes would have to set their inter-packet delay > > > > for the broadcast group to end up with a 1X packet injection rate. > > > > > > So, basically, MVAPICH doesn't have code that does either the group > > > creation properly when there is a mixture of HCA bandwidths, or limit > > > the packet injection rate. And IPoIB could violate this rule depending > > > on how user programs use it, e.g. if I did a lot of broadcasting, I > > > could easily exceed 1X's bandwidth. > > > > > > So this is more than just a "fix OpenSM" issue. It's more of a "fix > > > the spec" issue, if I'm understanding it correctly. > > > > No, the spec is fine. This is a "fix the SW" issue. If OpenSM > > rejected join requests of nodes for which the MC group is unrealizable > > (that is, some setting of the requestor conflict with the existing > > group, such as the rate), such nodes would not be able to join the > > broadcast group and thus not have IPoIB connectivity. > > I thought there were 2 issues here: > 1. OpenSM not checking the realizability of the join request > and > 2. The spec issue with discerning the reason for SA refusal of the joing > request
That's correct, but neither of the above indicates a fatal flaw in multicast handling in the IB specification. Though I guess I overstated things when I said "the spec is fine". The spec could be better, but it's not broken. How's that? ;) - Fab _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
