wangjw@usceast.cs.scarolina.edu (Jingwen Wang) (11/28/90)
Dear Networkers, As you may know, many applications need multicast communications and broadcast communications. However, todays hypercube computer, N-cube/10, for example, does not have such functions. You have to effect this by sending a separate message to every other nodes. This, in fact, includes too many duplicated transmissons, since some nodes have to forward this same information many times. I know some people have done some research in this area, such as the Yale University, but I wonder why these algorithms are not implemented in the commercial products now, although such algorithms were ready several years ago. Can anyone out there give an answer to this? Does it make sense if we try to implement these algorithms now? Jingwen Wang Department of Electrical and Computer Engineering University of South Carolina Columbia, SC 29208 E-mail:wangjw@usceast.cs.scarolina.edu
berryman-harry@CS.YALE.EDU (Harry Berryman) (11/29/90)
In article <11912@hubcap.clemson.edu> wangjw@usceast.cs.scarolina.edu (Jingwen Wang) writes: >Dear Networkers, > As you may know, many applications need multicast communications and >broadcast communications. However, todays hypercube computer, N-cube/10, >for example, does not have such functions. You have to effect this by [ Stuff deleted ] >Jingwen Wang The Intel iPSC/2 and iPSC/860 hypercubes have somewhat better libraries than the old NCUBE. Included are functions for global syncs, multicast, global reductions, interupt driven communication, and some other useful stuff. I cannot speak for the NCUBE2, but the old NCUBE was a real bear to work with because of the lack of any solid software support. This is not to imply that Intel has done a very good job supplying system software, just that NCUBE's is (or at least was) much worse. Scott Berryman Yale University CS Dept. (berryman@cs.yale.edu) or ICASE/NASA Langley Research Center (berryman@icase.edu)
joes@ncube.com (Joe Sikorski) (11/30/90)
In article <11917@hubcap.clemson.edu> berryman-harry@CS.YALE.EDU (Harry Berryman) writes: >In article <11912@hubcap.clemson.edu> wangjw@usceast.cs.scarolina.edu (Jingwen Wang) writes: >>Dear Networkers, >> As you may know, many applications need multicast communications and >>broadcast communications. However, todays hypercube computer, N-cube/10, >>for example, does not have such functions. You have to effect this by > [ Stuff deleted ] >>Jingwen Wang > >The Intel iPSC/2 and iPSC/860 hypercubes have somewhat better libraries >than the old NCUBE. Included are functions for global syncs, multicast, >global reductions, interupt driven communication, and some other >useful stuff. I cannot speak for the NCUBE2, but the old NCUBE was [ remainder of message deleted ] I've discussed with Dr. Erik DeBenedictis, Staff Scientist at nCUBE, the technical issues mentioned in the messages above. He made these comments about those issues: The nCUBE 2 hardware has a broadcast mode as part of the hypercube wormhole router. Now, use of this hardware is somewhat restricted due to the possibility of broadcast deadlocks (as first discovered on the Cosmic Cube). In current software, when the host or any node sends a message to destination -1, the message is broadcast to all nodes in the subcube (including the sending node, but not including the host even if sent from the host). Broadcast messages are relayed by the kernel to node 0 (unless they originate on node 0), which then uses the broadcast hardware to send to all nodes. Multicast is currently under consideration for the nCUBE 2. Uniformly efficient methods of specifying the set of target processors have not been found. Suggestions are welcome. The nCUBE 2 software library includes global synchronization, and global operations. Some reactive kernel primitives are available on an experimental basis. The Express library from Parasoft is bundled with all software releases. His comments are based on Release 2.0 of nCUBE's software for the nCUBE 2 series of massively parallel supercomputers. Release 2.0 will be generally available at the end of this year. --Joseph Sikorski, nCUBE Product Marketing nCUBE; 20 Davis Drive; Belmont, CA 94002 joes@ncube.com