[Wien] 2 XEON 5355 or 4 XEON 5150?

[Florent Boucher]

Dear Wien users,
it is important to know how you will work with your computer.
If you buy nodes with 8 intel core (2 sockets with 4 cores each), do you 
plane to use the 8 cores for the WIEN2K ?
In that case, if you look the benchmark results below, it is not a good 
solution !

bi-Xeon 5320 (overcl 2.67GHz)    119 sec    ifort9.1 + mkl9.0 (1 job with 1 threads)
bi-Xeon 5320 (overcl 2.67GHz)     90 sec    ifort9.1 + mkl9.0 (1 job with 2 threads)
bi-Xeon 5320 (overcl 2.67GHz)     76 sec    ifort9.1 + mkl9.0 (1 job with 4 threads)
bi-Xeon 5320 (overcl 2.67GHz)     69 sec    ifort9.1 + mkl9.0 (1 job with 8 threads)
bi-Xeon 5320 (overcl 2.67GHz)    122 sec    ifort9.1 + mkl9.0 (2 jobs with 1 thread)
bi-Xeon 5320 (overcl 2.67GHz)    159 sec    ifort9.1 + mkl9.0 (4 job with 1 thread)
bi-Xeon 5320 (overcl 2.67GHz)    286 sec    ifort9.1 + mkl9.0 (8 job with 1 thread)

You can see that even an overclocked solution run slower than an AMD 
when putting 8 jobs on it !
The memory band width is much lower than on AMD, due to the memory 
architecture. It is better in that case to by more nodes with less 
expensive AMD chips for which the efficiency is much better when the 
load average is close to 100%.
If you plane to use only 4 cores of the 8 cores for WIEN2K, than the 
Intel is a good solution. The problem is even worse with VASP that use 
an iterative diagonalization scheme and I suspect that the new algorithm 
implemented in WIEN2K for the iterative scheme will suffer even more on 
Intel than on AMD.

For information, we have been able to buy a solution with 20 nodes from 
a well known company (1U, 2 x AMD 2.8GHz bicore, 8Go DDR2 per node, 
Infinipath DDR 4X, warranty 3 years) for less than 50k€ (without taxes). 
The power consumption for such a configuration will be less than 7kW/h.

In case of an intel configuration, it is important to know what type of 
memory is used (FBDIM or DDR2).
Regards
Florent


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| Florent BOUCHER                    |                                    |
| Institut des Matériaux Jean Rouxel | Mailto:Florent.Boucher at cnrs-imn.fr |
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