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Subject: Re: Source code to measure it - results

Author: Robert Hyatt

Date: 21:29:43 07/15/03

Go up one level in this thread

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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