Paper showing Linpack scalability of mainstream clusters
Carlos O'Donell Jr.
carlos at megatonmonkey.net
Thu Sep 27 18:24:18 PDT 2001
> > So for the I-cluster that would have been
> >
> > 75 Gflops/(210 * 50 W/1000) = 7.14GFlops/kW
> >
> > Roger, out of curiosity could you do a similar calculation?
>
>
> I checked our UPS before and after powering up the first 128 nodes (256
> PIII 1GHz, 1GB, 20GB IDE), and came up with around 20kVA of power draw.
> I haven't converted that to Wattage (they are running at 208V,
> if anyone wants to do the math).
>
>
kVA's are simply apparent power rather than average power or Watt's.
They should be almost the same thing if the power factor of the PC supply
is relatively "good."
P = Vrms*Irms*cos(theta_V - theta_I)
Where (theta_V - theta_I) is the phase difference between voltage and curent.
The cosine is dimensionless and thus it really is still watt's.
And if the supply is _good_enough_ then it will approach 1 and give
you the worst case GFlops/kW ;)
So XX GFlops/(20,000W/1000) = XX GFlops / kW
Cheers,
Carlos.
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