Dual Core vs HyperThreading vs Dual CPU

Wojciech Puchar wojtek at tensor.3miasto.net
Tue Jan 10 11:50:57 PST 2006

> I'm going to assume that Dual Core is better (can't believe that they took a 
> step back) ... but, is how does it rate?  I know that HyperThreading is 
> definitely != Dual CPU ... but how close does Dual Core get?
Dual Core = two physical CPUs, possibly sharing L2 cache.

HyperThreading = double sets of registers, machine states etc... for 
single CPU making it look like 2 CPUs. when one "CPU" has to wait for say 
memory access, it then executes program from other thread.

it means it can be faster than single CPU, but of course much slower than 
2 CPUs. because this strategy make cache data shared and often switched 
between two different threads, it can result slower performance.

the net effect is positive in Intel's tests, but very little positive-to 
little negative in practice like FreeBSD servers.

Many users end in running single-CPU kernel because it actually works 

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