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Re: cpu arch performance



On Tue, 23 May 2000, Lee Elliott wrote:

> Hello list(s),
>  
> Just something I noticed after setting up an x86
system after running
> Debian on m68k.
> 
> The m68k system was an Amiga with an m68060/50MHz
which gave a 
BogoMIP
> rating of 99.something.  The x86 system is a dual
PIII 650MHz system 
and
> it rates as 2600 BogoMIPs.  This would seem to imply
that on a per 
MHz
> basis, the m68060 is the equivalent of two PIIIs.

This is right. 
AFAIK, the hardware side of the issue goes something
like this:
One phase of the clock signal looks something like
this:

Voltage
high      ____
         |    |    |
low      |    |____|

The x86 Processors will issue a command whenever the
signal voltage is
high. The m68k processors will issue a command
whenever the signal 
voltage
is high and the next when it's low (Motorola claims,
that the 68060
issues three commands per clock cycle, I don't know
why you then don't 
get
three times  the MIPS value of a x86 on a per MHz
basis. I also don't
know if the above mentioned holds true for Pentium and
upwards. But it
holds true for 386 and 486). This is why a m68k
processor is on a per 
MHz
basis really twice as fast as a x86 processor.
Regards,
Daniel

-----------------------------------------------------
The AMD K6 also gives about 2x the clock in bogo mips.
 Not sure about the K7/Athlon though.

=====
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http://www.qsl.net/wa2mze

Debian Gnu Linux, Live Free or .....



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