Author: Vincent Diepeveen
Date: 08:59:18 12/27/05
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On December 27, 2005 at 08:03:29, Thomas Lagershausen wrote: >On December 27, 2005 at 07:57:28, Ernst Walet wrote: > >>On December 27, 2005 at 07:36:44, Jouni Uski wrote: >> >>>What's average node speed now? >>> >>>Jouni >> >>I saw about 16 million nps in the middle game. >> >>Ernst. > >Wow, this will be nice in complicated positions. > >We can expect fire on the board. > >Thomas Those machines are about 6 meters wide, 3.5 meters high, 34 meters tal. the total machine has 32 + 512 + 512 processors = 1066 processors. nicest is to play with the 32p partition, however they just use that as compile partition and to testrun for a few minutes your program before putting it in the batch system. the altix3000 series are nice machines, but it eats a lot of time before you can fix a program for it. also there is always issue. biggest issue zappa seems to have is i guess that the itanium2 cpu doesn't deliver what he had hoped it would deliver. it's missing a factor 2 somewhere. you know, even a 32 bits program like diep at 1.6Ghz itanium2 performs like at a 1.8Ghz opteron. i forgot speeds of zappa, but i guess it gets around 900k nps single cpu at an opteron 2.2Ghz, whereas reports are it gets single cpu itanium2 around 300k nps. Erdo reported to me just now he hits roughly 20 million nps with Zappa, and we know from Ernst it's 16M worst case. that means in short at 100 cpu's scaling = 100% * 20 million / 0.3M * 100 = 100% * 2/3 = 66.66% Official SGI guidelines say a program scales well when you scale above 50% at those supercomputers. They were very amazed when i was not happy with 90% scaling of diep and improved it to 100%. I must admit i'm a bit amazed that a bitboards program is relative seen 2x slower than diep on those itanium2 cpu's. Perhaps it is because diep has a lot of branches. Perhaps Cozzie can comment on how many he got in Zappa. Vincent
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