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SubjectRe: Re: bogomips ??? == Bogus MIPS
On Fri, Apr 23, 1999 at 06:03:00AM -0800, ddavis@carolina.rr.com wrote:
> This is a question I was wondering about. Why do the AMD chips
> usually return a double MHZ value? Are they really twice as
> fast as an Intel chip when checking the loop you mentioned?
>
> Daniel

It's a false penis-size CPU measurement. The K6 has always done null-loops
faster, and this is also why the K6 exposed a bug in Windows 95 which took a
result of such a loop and divided a number by the result. Well once the K6 was
hitting 350mhz and above, the result ended up being 0. Bam. Divide by zero in
kernel-space == BSOD on every other boot (in general). Get into the 400mhz
range and it would do it everytime. M$ had the balls to charge people for the
fix, even though the bug was in their code and not the CPU.

I might have botched the explaination up above but that is the general case of
what was going on.

My old AMD 5x86-133 has better bogomips (by far) than any of the original
Pendulms but its performance is in the P90 range (unless you run it at 160/40
and it is closer to a P100)

The general rule is that K6-based cores will get 2x the bogomips of the actual
Mhz rating and .25 micron P2's will get 1x the actual Mhz rating. My DEC Alpha
gets almost 1-to-1 corrospondance too.


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