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Subject: Re: random access latency opteron versus k7

Author: Dieter Buerssner

Date: 14:37:41 05/30/04

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On May 30, 2004 at 16:15:54, Robert Hyatt wrote:

>I have no idea what your program above does [, and really don't care.]

You could have an idea. I showed the source here, and we discussed it.
http://chessprogramming.org/cccsearch/ccc.php?find_thread=306858

It tries to answer the question: How long do I need on average, to access a
random word in memory - from programmers point of view. I have a large array of
words, and need to know the value at one random index (a situation very
comparable to hashing in chess). The program does not care about how many TLB
read are needed - just the time until it will have the value (say in a
register). It is the time of one move instruction

movl (%eax), %eax

or in Intel syntax

mov eax, DWORD PTR [eax]

where, before the instruction eax points to some (valid) word (correctly aligned
for a pointer), randomly.

Regards,
Dieter



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