Author: José de Jesús García Ruvalcaba
Date: 10:26:26 10/31/98
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On October 31, 1998 at 10:40:58, Robert Hyatt wrote: >On October 30, 1998 at 14:43:19, José de Jesús García Ruvalcaba wrote: >> >>What would be the expected performance of craty on a 64-processor Sun Enterprise >>10000? >>As far as I understand, it has symmetric multiprocessing. > > > >Assuming no "bottlenecks" it should be roughly .7*64 times faster. However, >I wouldn't be certain that the .7 holds... IE I have a single lock for each >of the two hash tables. With 64 cpus, that is likely going to produce some >blocking conditions. I carefully only lock while I read an entry then unlock, >but it is possible that this will start to add up. Not having a 64 processor >machine to work on, I can only speculate. In Cray Blitz, with 32 processors, >I didn't see significant blocking... but there I did everything in assembly >and the lock/load/unlock and lock/store/unlock for hashing was *very* quick. > >Also I don't know how sun has done their 64 processor architecture. A non- >blocking crossbar is very expensive for 64 processors. Also, what about memory? >Cray uses a bunch of memory banks (things that can do 2 reads and 1 write at >the same time) to avoid processor stalls. What does Sun do? If the memory >bandwidth isn't there, then the .7 is going to shrink... I will find out the technical details, they appeared in Unix's review a few months ago. But for seven million dollars, I think they ought to provide something good!
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