Results

The results of optimising the evaluation of the Van Der Waal's forces are shown in table [[*]].


Table: Timing comparison of different runs with Bak on XT4, XE6 and optimised vdw_forces on XE6
Nb. Procs Bak XT4 Bak XE6 Opt vdw
16 199.154 218.722 212.913
32 106.790 98.113 94.590
64 63.129 57.494 56.761
128 42.036 39.360 35.121
256 27.471 29.492 25.631
512 22.137 25.951 21.641


The optimised version of vdw_forces shows a speed up of in average over all runs.A peak is observed at speed up compare to the Bak version on XE6 for 512 processes run.


Table: Variation rate of different runs of optimised vdw_forces on XE6 with Bak on XT4 and XE6
<#1177#> Opt vdw comp. to  
  Bak XT4 Bak XE6
16 6.91 -2.66  
32 -11.42 -3.59  
64 -10.09 -1.27  
128 -16.45 -10.77  
256 -6.7 -13.09  
512 -2.24 -16.61  
Average -6.67 -8.00  


Valène Pellissier 2011-08-24