[Beowulf] Theoretical vs. Actual Performance

[Dmitri Chubarov]

Hi,

not sure if the 282 GFLOPS number is correct.

We have 16 Bulldozer/Interlagos cores at 2.2 GHz. Each pair of cores forms
a CMT module. The two cores in the module share an FPU with 2 128-bit FMAC
units.

In terms of double precision FLOPS it should make
16 * 2.2GHz * 2 double precision scalars/SIMD register * 2 FLOPS / FMA op =
140.8 GFLOPS

It looks like 282 GFLOPS number is per a 2P node.

Dima

On 22 February 2018 at 21:37, Prentice Bisbal <pbisbal at pppl.gov> wrote:

> Beowulfers,
>
> In your experience, how close does actual performance of your processors
> match up to their theoretical performance? I'm investigating a performances
> issue on some of my nodes. These are older systems using AMD Opteron 6274
> processors. I found literature from AMD stating the theoretical performance
> of these processors is 282 GFLOPS, and my LINPACK performance isn't coming
> close to that (I get approximately ~33% of that).  The number I often hear
> mentioned is actual performance should be ~85%. of theoretical performance
> is that a realistic number your experience?
>
> I don't want this to be a discussion of what could be wrong at this point,
> we will get to that in future posts, I assure you!
>
> --
> Prentice
>
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