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Subject: Re: Source code to measure it

Author: Vincent Diepeveen

Date: 17:04:40 07/15/03

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On July 15, 2003 at 10:25:25, Gerd Isenberg wrote:

>Hi Vincent,
>
>Thanks, for the source code. I will try it during the next days...
>How long will the test run?
>
>Another interesting thread about this issue:
>
>http://www.sandpile.org/post/msgs/20003914.htm
>http://www.sandpile.org/post/msgs/20003911.htm
>
>with some comments from Paul Hsieh:
>
>http://www.sandpile.org/post/msgs/20003912.htm
>
>It would be interesting to compare the results from lm-bench with Oliver's and
>your's on different hardware.
>
>Regards,
>Gerd

Note that the test i shipped you allocates 1 big memory block in OpenMP.
For clusters having openMP or cc-NUMA machines having openMP it is better to use
my latencyC.c test which allocates locally a hashtable at each processor and
with openMP connects it to each other. Then they read randomly from each
processor.

I already have enough results from different supercomputers and PC's at both
testsets to know what is good in at SGI supercomputers and supercomputers in
general and what is not so good there.

However i would love to get from both testsets some results back from opterons
and dual opterons. that would be real cool.

don't have any yet. we know the sequential latency is 40-50 ns claimed. so let's
see what the time is to get 8 bytes at a random adress out of memory.

I'm hoping for < 150 ns or something of course. I fear it's only slightly better
than the 280ns that P4/K7 delivers single cpu. Like 20% at most.

So like 200 ns.




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