[RC5] Power PC G4 vs. G5

bert bertodell at charter.net
Mon Aug 1 19:38:55 EDT 2005


So you're saying that in order to crack RC5-72 blocks it would be better 
to ignore a G5 machine and go with a G4 machine?

Bert

Décio Luiz Gazzoni Filho wrote:

>
> On Aug 1, 2005, at 8:07 PM, Ben Payne wrote:
>
>> I have been very surprised by the relative performance of the G4  and 
>> the G5 processors.  I’m hoping that some people here can  confirm my 
>> finding and/or possibly explain why this would be  occurring.  I have 
>> noticed that the 7450 core is the fastest for  both the G4 and G5 
>> processors.  I have also noticed that there is a  970 core but it has 
>> been disabled.
>>
>>
>>
>> So here are the numbers I’m getting:
>>
>>
>>
>> I have a dual processor G5 1.8 GHz it does ~18 million keys a sec
>>
>> I have a 1.4 GHz mac mini that does ~15 million keys a sec.
>>
>>
>>
>> That all sound good until you add the fact that the G5 has two  
>> processors and is actually clock-for-clock less than 50% the key  
>> rate of the G4.
>>
>>
>>
>> G5: 18 / 1.8 / 2 = 5 million keys per sec per GHz per CPU
>>
>> G4: 15 / 1.4 = 10.7 million keys per sec per GHz per CPU
>
> Have you considered the possibility that the G5 Altivec unit is  
> crippled and can't hope to reach the same throughput as the 74xx's  
> Altivec unit?
>
> As far as I know, what you're seeing is perfectly normal.
>
> Décio
>
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