On Tue, Jul 15, 2008 at 4:16 PM, Sean Hefty <[EMAIL PROTECTED]> wrote: >>>> To create a path record, IPoIB needs the following values (in addition >>>> to the ones it has access to for the AV creation): >>> >>> You don't need to create a PR, versus just creating the AV. >> >>I do if I want to give it to the CM to establish an RC connection. Phase 2 >>(creating PRs) is specifically to avoid the PR lookup for users of IBAT. >>Basically, rather than returning a GID pair, IBAT would return a path record. >>IPoIB would create that path record. This effectively eliminates path >>queries, >>which should help things scale. > > I thought you were only talking about using AVs for IPoIB, not having IPoIB > return PRs for someone else's use. > > As long as there are separate interfaces for getting PRs - one that goes to > the > SA, and another that goes to some magic PR generating entity, there shouldn't > be > any harm. An application that wants magical generated PRs just needs to be > aware of the limitations of pixie dust. > >>Come to think of it, this affects AV creation too - to create a local AV >>without getting the path record means that you assume that the path is >>reversible (otherwise you can't use the SLID of a received packet as DLID for >>a >>send packet, can you?) > > I was thinking that the generated AV would be reversible, but the message was > received as multicast and goes out as unicast... So, this solution limits the > subnet topologies, but I'm not sure how big an issue that is in practice. > Both > the windows and linux IB CM's only support reversible paths. > >>Looking at OpenSM, it always sets the rate to 12 (OSM_DEFAULT_SUBNET_TIMEOUT), >>both for MC groups as well as for path records. > > This sounds more like packet lifetime, versus rate.
Yes, you're right but there's configuration of packet lifetime as well as rate configuration supported in OpenSM. -- Hal >>I can trap that easily enough - if the subnet prefix is different, I can >>return >>a path that only has the GID/LID pairs filled in. The CM code can then detect >>if everything else is zero, and issue a real path query. While a bit >>convoluted, it avoids having to return PENDING from the IBAT library. > > I wouldn't put path selection logic into the CM. But I also wouldn't worry > about crossing an IB router at this point. The current PR format doesn't work > anyway because you need LID information for both the local and remote subnets. > > - Sean > > _______________________________________________ > ofw mailing list > [email protected] > http://lists.openfabrics.org/cgi-bin/mailman/listinfo/ofw > _______________________________________________ ofw mailing list [email protected] http://lists.openfabrics.org/cgi-bin/mailman/listinfo/ofw
