Author: Robert Hyatt
Date: 21:29:43 07/15/03
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On July 16, 2003 at 00:05:29, Keith Evans wrote: >On July 15, 2003 at 23:35:30, Robert Hyatt wrote: > >>On July 15, 2003 at 23:05:37, Vincent Diepeveen wrote: >> >>> >>> >>>Now i can disproof again the 130ns figure that Bob keeps giving here for dual >>>machines and something even faster than that for single cpu (up to 60ns or >>>something). Then i'm sure he'll be modifying soon his statement something like >>>to "that it is not interesting to know the time of a hashtable lookup, because >>>that is not interesting to know; instead the only scientific intersting thing is >>>to know is how much bandwidth a machine can actually achieve". >>> >> >> >>What is _interesting_ is the fact that you are incapable of even recalling >>the numbers I posted. >> >>to wit: >> >>dual xeon 2.8ghz, 400mhz FSB. 149ns latency >> >>PIII/750 laptop, SDRAM. 125ns. >> >>Aaron posted the 60+ ns numbers for his overclocked athlon. I assume his >>numbers are as accurate as mine since he _did_ run lm_bench, rather than >>something with potential bugs. >> >>I can post bandwidth numbers if you want, but that has nothing to do with >>latency, as those of us understanding architecture already know. >> > >Can you run lmbench and give the latency numbers for different stride sizes? >Then you could quote numbers from cache,... > Here's my laptop data. L1 seems to be 4 clocks. L2 9 clocks, memory at 130ns. This is a PIII/750mhs machine with SDRAM. I just ran it again to produce these numbers. Host OS Mhz L1 $ L2 $ Main mem Guesses --------- ------------- --- ---- ---- -------- ------- scrappy Linux 2.4.20 744 4.0370 9.4300 130.2 >In the lmbench paper they have a nice graph like this. Is the above what you want?
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