Re: AW: AW: 2CPU+1GPU vs 1CPU+2GPU

From: Nicholas M Glykos (
Date: Wed Feb 15 2012 - 03:22:43 CST

Hi Norman,

> And for a small number of nodes, Gigabit is very sufficient, whereas GPU
> nodes would already need expensive Infiniband or 10Gbit/s-Ethernet.

Even with old CPUs (quad-core Q6600), loaded with consumer GPUs (GTX 460,
one card per node) and with simple gigabit, you can have useful speedups
for small (tiny) number of nodes and large-ish systems (say, 100K atoms).
To put this in numbers using the ApoA1 benchmark (measurements in ns/day):

Nodes/Cores/GPUs With CUDA Without CUDA Times faster with CUDA
   1 / 4 / 1 1.11 0.22 5.04
   2 / 8 / 2 1.79 0.42 4.25
   4 / 16 / 4 2.27 0.77 2.94

Although the parallel scaling with CUDA (at ~68% with four nodes) is far
from ideal, for small (tiny) research groups which can relax the big
cluster rules, this may still be a useful toy-cluster. Having said than,
you can substitute the whole lot discussed above (4 nodes + LAN) with a
single (cheap) node based on an AMD 8-core FX-8150 plus one GTX 570 card
which for the same benchmark delivers 2.33 ns/day.

My twocents,

            Nicholas M. Glykos, Department of Molecular Biology
     and Genetics, Democritus University of Thrace, University Campus,
  Dragana, 68100 Alexandroupolis, Greece, Tel/Fax (office) +302551030620,
    Ext.77620, Tel (lab) +302551030615,

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