Richard Walsh wrote: > why not just use an FPGA ... ;-)
I taught myself VHDL and programmed two algorithms in Mitrion-C, but I decided that less general hardware such as CBE (Cell) is better for HPC. I made an estimate of how much area on a FPGA is needed for a group of controllers (the smallest type, pico-Blaze) for having software control of the arithmetic and the area for communications and decided that CBE is much faster for the same funtionality. FPGA is just too general for HPC. It reminds me of the evolution of Thinking Machines in which they started at the bit-level then built machines with Weitek ALU's at the end of each row. I would like to add that the algorithms that I see are often not purely SIMD though they are parallel. CBE is partially SIMD in that each processor can work on 4 4-byte words with the same operation, but in addition there are 8 special purpose processors each with their own instruction stream. Examples of high speed-ups for SIMD problems is like picking the low-lying fruit. IMHO having many instruction streams allows speed-up of algorithms that involve many logical decisions -- what comes to mind is Monte Carlo simulation of the flow of genes in pedigrees for finding the genetic component of somatic attributes. More generally, pointer chasing. MIMD at a high level of core (instruction sequencer) integration would give a performance boost to an interesting sector of algorithms of the pointer chasing type. I have not written algorithms for the CBE, so my remarks on that aspect may be ignorant. best regards, Alan Scheinine -- Centro di Ricerca, Sviluppo e Studi Superiori in Sardegna Center for Advanced Studies, Research, and Development in Sardinia Postal Address: | Physical Address for FedEx, UPS, DHL: --------------- | ------------------------------------- Alan Scheinine | Alan Scheinine c/o CRS4 | c/o CRS4 C.P. n. 25 | Loc. Pixina Manna Edificio 1 09010 Pula (Cagliari), Italy | 09010 Pula (Cagliari), Italy Email: [EMAIL PROTECTED] Phone: 070 9250 238 [+39 070 9250 238] Fax: 070 9250 216 or 220 [+39 070 9250 216 or +39 070 9250 220] Operator at reception: 070 9250 1 [+39 070 9250 1] Mobile phone: 347 7990472 [+39 347 7990472] _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
