GMP 4.3.1 misdetects intel X7460

David Harvey dmharvey at
Sun Jul 26 13:04:40 CEST 2009

On Jul 26, 2009, at 12:12 PM, Torbjorn Granlund wrote:

> Any idea of what type of processor that is?  There are, to my  
> knowledge,
> three different "core" microarchitecture variants.
> Gen 1, 65nm "Core 2" with Conroe, Merom, etc, with slow integer  
> division
> Gen 2, 45nm, "Core 2" with Penryn, with faster integer division
> Gen 3, 45 nm, "Core iN", Nehalem with Bloomfield,Lynnfield with many
> pipeline differences (better pipelining, sometimes longer latencies)
> Do you know to which of these "model 29" belongs?

No, I have no idea. This is All I know is  
from /proc/cpuinfo. It's a 24-core machine. I could ask William Stein  
for more info if that helps, he probably knows more about it.

> If not, please run and time this program, it will tell the latter two
> apart:
>         .globl  main
> main:
>         mov     $2666666667, %ecx
> 1:      mul
>         dec     %ecx
>         jnz     1b
>         ret

I changed the "mul" to "mul %rbx", and got 6.94s.


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