Author: Vincent Diepeveen
Date: 18:44:21 04/28/05
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On April 28, 2005 at 18:13:03, Frank E. Oldham wrote: I really wonder why they have SMT on those processors. More and more it is obvious to everyone that replacing 1 good working car tyre by 2 very thin bicycle tires is not a good idea. >On April 28, 2005 at 13:51:02, Robert Hyatt wrote: > >>On April 28, 2005 at 07:52:27, Vincent Diepeveen wrote: >> >>> http://www.sudhian.com/showdocs.cfm?aid=667&pid=2543 >>> >>>In world champs 2004 at quad opteron 2.0Ghz diep got about 380k nps in >>>openingsposition. >>> >>>529k nps at dual core dual opteron. It's just incredible. Scaling 3.92 >>>Quad opteron world champs 2004 scaled 3.93 >>> >>>This was a net2003 executable compiled in 32 bits. Intel c++ compiles were >>>slower. >> >> >>I think their data or test is a bit broken. I have dual PIV's here, both my >>xeon, and a dual 3.6 in the lab. My scaling from 1 to 2 threads (no >>hyper-threading turned on) is way better than 1.67X using 2 threads. >> >>For example, on my dual xeon, a quick test produced 1.51M nps using a single >>processor, 2.89M using both. Which is a 1.91X increase in NPS. >> >>On a 4-way 850, I have large tests that produce 2.32M for one cpu, 8.69M for >>four cpus, which is 3.75X faster. Comparing apples to apples, the dual 850 NPS >>was 4.53M, which turns into 1.95X faster. So for me, the dual xeon and the dual >>opteron produce almost identical NPS scaling, although the opteron is about 2x >>faster per cpu... > >Hi Bob, >it looks like their 4-thread test is one dual-core P4 running hyperthreading >versus two dual-core opterons. :-) >Frank
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