On Thu, 2008-01-03 at 09:49 +0200, Eli Cohen wrote: > On Wed, 2008-01-02 at 10:16 -0800, Roland Dreier wrote: > > > In the majority of cases, if the neighbour will change, it will > > > be reflected in the guid part of the GID (bytes 8-15). If the GID > > > prefix will change as well (bytes 0-7) it will be because the master > > > SM has changed, in which case we will get an SM change event resulting > > > in all paths flushed. > > > > Is it guaranteed that an active SM can't change a GID prefix? > I know opensm has a fixed, hard coded subnet prefix.
OpenSM's subnet prefix is determined via a config file (or defaults if not overridden there). There has been discussion about supporting reconfiguration without OpenSM restart. (One can also envision a restart scenario here where the subnet prefix is changed). Also, OpenSM is not the only SM out there and IMO ideally we would/should rely on only what the IBA architecture requires and not on current implementation. -- Hal > > Especially if we're using a GID at an index != 0? > I think ipoib uses only the GID from index 0, isn't it? > > In other words, is > > this change definitely 100 percent safe? > It looks safe to me but I wanted to hear other opinions. > > > > Also I assume this change is coming from performance tuning. For > > patches like this it is always helpful to include hard data like "this > > gives a speedup of X on test Y on system Z." > > > > Thanks... > Indeed I am working on performance and on the branch I am working on, > which is different than main branch, it does makes a slight difference. > I am trying to improve the throughput of small (up to 128 bytes) UDP > messages where I am CPU bound so everything counts. But I believe that > if it is correct than we should use it even if the improvement is not > outstanding. > > > _______________________________________________ > 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 _______________________________________________ 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
