[SATLUG] comparison of processors (OT)

[Jeremy Mann]

I think he was really interested in the timing differences between
Intel and AMD Opteron.



On 8/1/05, Don Wright <wmail at wricomp.com> wrote:
> On Mon, 1 Aug 2005 09:04:43 -0500, Jeremy Mann
> <jeremymann at gmail.com> wrote:
> 
> >The question was actually asked by an intern here in my office. I
> >figured somebody on this list would have an answer. He has since wrote
> >a program to figure out the timing. Thanks again.
> 
> You may find the timings are much less dependent on the numbers
> being multiplied. Since transistor count is not as much of an
> issue any more, many processors use a lookup table to multiply,
> for example, 8 bits at a time using a 256x256 table of 16-bit
> results, or 131,072 bytes. That's a small ROM compared to the
> on-board L1/L2 cache.  --Don
> 
> 
> >On 7/30/05, Travis H. <solinym at gmail.com> wrote:
> >> > >> Back in the i386 days, multiplication took a variable amount of time,
> >> > >> depending on the number of leading zeroes in the binary representation
> >> > >> of multiplier.  Oddly, this was asymmetric; multiplying 2 by 100 took
> >> > >> more time than multiplying 100 by 2.
> 
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-- 
Jeremy