Author: Robert Hyatt
Date: 21:56:17 01/31/05
Go up one level in this thread
On January 31, 2005 at 13:35:02, Vincent Diepeveen wrote: >On January 31, 2005 at 13:03:43, Robert Hyatt wrote: > >>On January 31, 2005 at 10:14:28, Vincent Diepeveen wrote: >> >>>On January 31, 2005 at 10:01:16, Vincent Lejeune wrote: >>> >>>> >>>>news from 28/01/05 (more to come) >>>> >>>>http://hydrachess.com/hydra-scylla.html >>>> >>>>32 nodes (previous version has 16) , no information about CPU power and FPGA >>>>cards yet ... >>> >>>It's 4 nodes. >>> >>>1 node = 8 processor Xeon. >>> >>>FPGA cards would get double speed. So must be between 30Mhz and 60Mhz. They only >>>use development fpga cards. So never use the real power of fpga (which is >>>printing your own processor which can run hands down at 600Mhz or more). They >>>stick to development cards for some unknown reason to me. >>> >>>CPU power is not interesting at all of course, cards do the work. >>> >>>Vincent >> >>I hope not. Old machine used 8 boxes with 2 cpus per box. Going to 8-way xeons >>is a performance killer. The PCI bus just can't keep up. > >Ok the sheikh nor his righthand didn't know himself very well the architectural >details which we will forgive them. > >I have accurate information now. > >It is a 32 node system. With each node a dual. They have however 32 FPGA cards >because when ordering the person filling in the form (and i am NOT going to post >who it was, but it was NOT the sheikh) confused nodes for cpu's. > >So they have a mighty 32 node myrinet now with 64 processors. However 32 cards >so they run 64 processor effectively while serving with 32 cards which do the >job. Cards at 55Mhz. > >Please note that PCI bus isn't the problem. They are using pci-x. PCI-X falls flat if you have 8 cpus in a single box. I have run on such machines. PCI does pretty well on 4way systems, but on 8-way, overall gain seems to be 1.5x a 4-way which is not that great. If you run a program that runs out of cache quickly, this drops even further. > >Latency of one way pingpong is around 2.7 us with myrinet. That excludes the >router costs which will be also at about 1 us i guess for random data traffic >(up to 35 ns for bandwidth traffic). > >Vincent All depends. We have myrinet here and are probably going to use that in our new opteron cluster when we buy it after the dual-core opterons start shipping in quantity...
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