Path: utzoo!news-server.csri.toronto.edu!rutgers!mit-eddie!snorkelwacker.mit.edu!stanford.edu!eos!data.nas.nasa.gov!amelia!serafini From: serafini@nas.nasa.gov (David B. Serafini) Newsgroups: comp.arch Subject: Re: massive parallelism, was CDC 6600 and TI ASC Keywords: routing routers Message-ID: <1991Mar12.013029.22683@nas.nasa.gov> Date: 12 Mar 91 01:30:29 GMT References: <781@llnl.LLNL.GOV> <12315@pt.cs.cmu.edu> Sender: news@nas.nasa.gov Reply-To: serafini@amelia.nas.nasa.gov (David B. Serafini) Organization: Rose Engineering and Research Lines: 36 In article <12315@pt.cs.cmu.edu> lindsay@gandalf.cs.cmu.edu (Donald Lindsay) writes: >In article <781@llnl.LLNL.GOV> > brooks@physics.llnl.gov (Eugene D. Brooks III) writes: >>Scatter/gather is the equivalent of the communication on the CM. On >>a Cray XMP or YMP the scatter/gather bandwidth matches the cpu speed >>just fine and does not represent a bottleneck. It is certainly not >>as hampered as the "router" functionality on the CM-2 which is a severe >>mismatch for the PE computational bandwidth. > >It was mismatched on the CM-1, too. Would anyone care to comment on >why the CM-2 didn't improve in this area? Is there something >intrinsic to their design, or their implementation strategy? > The CM-2 was basically a CM-1 with floating point hardware and some extra glue circuitry stuck onto the boards in what little spare board space there was. Very little, if any, of the CM-1 hardware was majorly redesigned (to my knowledge. I may be wrong.) There were bug fixes, of course. It took a lot of time and effort to design the router hardware and software, and could not be redone for the CM-2. I'm sure the next CM will show the significant changes that Don is implying should have been in the CM-2. David B. Serafini serafini@ralph.arc.nasa.gov Rose Engineering and Research or ...!ames!amelia!serafini NASA/Ames Research Center MS227-6 (415)604-6233 Moffett Field, CA 94035 #include -- David B. Serafini serafini@ralph.arc.nasa.gov Rose Engineering and Research or ...!ames!amelia!serafini NASA/Ames Research Center MS227-6 (415)604-6233 Moffett Field, CA 94035 #include