From: Dan Bonachea (bonachea_at_cs_dot_berkeley_dot_edu)
Date: Tue Sep 13 2005 - 13:24:20 PDT
At 10:12 AM 9/13/2005, Adrian Powell wrote: > >Hi, > > I noticed in the 2.2.0 ChangeLog that it says to get in touch with you > all for XT3 >queries.... What's the deal with XT3 support ?. > Hi Adrian - The reason we don't directly encourage users to try BUPC 2.2 on XT3 is that our XT3 port is brand-new and all we've done so far is a "phase 1" port, where all UPC communication on that machine is performed using calls to an MPI-based compatibility layer. Consequently, the communication performance for BUPC programs on XT3 is currently somewhat worse than can be achieved by writing applications directly in MPI. However, we've recently opened a contract with Cray to do a "native" GASNet implementation on XT3, which will allow us to bypass the MPI layer and deliver communication performance for UPC programs comparable to (or hopefully even superior to) programs written directly for MPI. That support will likely be included in the next release. So basically we want to ensure any Berkeley UPC users trying out the XT3 understand that our XT3 support is still very much a "work-in-progress" and doesn't yet deliver the performance we expect to eventually provide on the XT3. This is mostly just an attempt to head off any potential for unfair performance comparisons by outside groups who may "discover" that BUPC on XT3 doesn't currently deliver the peak network performance. Provided you understand all this and are still interested in trying out the initial XT3 port, I can send you the additional file (not included in the distribution) that you'll need to do the build. Dan > Thanks, Adrian. > > >