[Getdp] GetDP MPI versus single CPU

[gilles quemener]

Hi, 

I have compiled GetDP with MPI option under Linux Ubuntu 16.04 on a machine w/ 6x2 CPUs and 32 MB of RAM. 
When running the magnet.pro file given in the GetDP demos folder, I was expecting to get faster results with MPI 
than w/o and was quite surprise by the comparison as shown by the following outputs : 

1) MPI run: 
*********** 

mpirun -np 12 /home/quemener/local/OneLab_gq/GetDP/bin/getdp magnet -solve MagSta_phi -pos MagSta_phi 
Info : Running '/home/quemener/local/OneLab_gq/GetDP/bin/getdp magnet -solve MagSta_phi -pos MagSta_phi' [GetDP 2.11.1, 12 nodes] 
Info : Started (Wed Aug 9 09:20:20 2017, Wall = 0.277839s, CPU = 0.884s [0.04s,0.116s], Mem = 287.254Mb [23.4609Mb,27.6289Mb]) 
Info : Increasing process stack size (8192 kB < 16 MB) 
Info : Loading problem definition 'magnet.pro' 
Info : Loading problem definition 'magnet_data.pro' 
Info : Loading problem definition '../templates/MaterialDatabase.pro' 
Info : Loading problem definition '../templates/MaterialMacros.pro' 
Info : Loading problem definition '../templates/Magnetostatics.pro' 
Info : Selected Resolution 'MagSta_phi' 
Info : Loading Geometric data 'magnet.msh' 
Info : System 'A' : Real 
P r e - P r o c e s s i n g . . . 
Info : Treatment Formulation 'MagSta_phi' 
Info : Generate ExtendedGroup '_CO_Entity_15' (NodesOf) 
Info : [rank 8] System 1/1: 1658225 Dofs 
Info : [rank 7] System 1/1: 1658225 Dofs 
Info : [rank 3] System 1/1: 1658225 Dofs 
Info : [rank 4] System 1/1: 1658225 Dofs 
Info : [rank 1] System 1/1: 1658225 Dofs 
Info : [rank 2] System 1/1: 1658225 Dofs 
Info : [rank 10] System 1/1: 1658225 Dofs 
Info : [rank 6] System 1/1: 1658225 Dofs 
Info : [rank 5] System 1/1: 1658225 Dofs 
Info : [rank 11] System 1/1: 1658225 Dofs 
Info : [rank 0] System 1/1: 1658225 Dofs 
Info : [rank 9] System 1/1: 1658225 Dofs 
Info : (Wall = 30.3178s, CPU = 181.936s [14.804s,16.964s], Mem = 8228.93Mb [685.133Mb,689.43Mb]) 
E n d P r e - P r o c e s s i n g 
P r o c e s s i n g . . . 
Info : CreateDir[../templates/res/] 
Info : Generate[A] 
Info : Solve[A] 
Info : N: 1658225 - preonly lu mumps 
Info : SaveSolution[A] 
Info : (Wall = 87.9995s, CPU = 489.904s [38.456s,48.752s], Mem = 14249.9Mb [1109.46Mb,1297.96Mb]) 
E n d P r o c e s s i n g 
P o s t - P r o c e s s i n g . . . 
Info : NameOfSystem not set in PostProcessing: selected 'A' 
Info : Selected PostProcessing 'MagSta_phi' 
Info : Selected Mesh 'magnet.msh' 
Info : PostOperation 1/4 
> 'res/MagSta_phi_hc.pos' 
Info : PostOperation 2/4 
> 'res/MagSta_phi_phi.pos' 
Info : PostOperation 3/4 
> 'res/MagSta_phi_h.pos' 
Info : PostOperation 4/4 
> 'res/MagSta_phi_b.pos' 
Info : (Wall = 377.562s, CPU = 1118.17s [80.556s,207.128s], Mem = 14254.1Mb [1109.95Mb,1297.96Mb]) 
E n d P o s t - P r o c e s s i n g 
Info : Stopped (Wed Aug 9 09:26:37 2017, Wall = 377.851s, CPU = 2012.12s [162.712s,207.26s], Mem = 14254.1Mb [1109.95Mb,1297.96Mb]) 


2) Single CPU run: 
****************** 

/home/quemener/local/OneLab_gq/GetDP/bin/getdp magnet -solve MagSta_phi -pos MagSta_phi 
Info : Running '/home/quemener/local/OneLab_gq/GetDP/bin/getdp magnet -solve MagSta_phi -pos MagSta_phi' [GetDP 2.11.1, 1 node] 
Info : Started (Wed Aug 9 09:27:06 2017, Wall = 0.146171s, CPU = 0.136s, Mem = 25.9609Mb) 
Info : Increasing process stack size (8192 kB < 16 MB) 
Info : Loading problem definition 'magnet.pro' 
Info : Loading problem definition 'magnet_data.pro' 
Info : Loading problem definition '../templates/MaterialDatabase.pro' 
Info : Loading problem definition '../templates/MaterialMacros.pro' 
Info : Loading problem definition '../templates/Magnetostatics.pro' 
Info : Selected Resolution 'MagSta_phi' 
Info : Loading Geometric data 'magnet.msh' 
Info : System 'A' : Real 
P r e - P r o c e s s i n g . . . 
Info : Treatment Formulation 'MagSta_phi' 
Info : Generate ExtendedGroup '_CO_Entity_15' (NodesOf) 
Info : System 1/1: 1658225 Dofs 
Info : (Wall = 10.7856s, CPU = 7.42s, Mem = 688.309Mb) 
E n d P r e - P r o c e s s i n g 
P r o c e s s i n g . . . 
Info : CreateDir[../templates/res/] 
Info : Generate[A] 
Info : Solve[A] 
Info : N: 1658225 - preonly lu mumps 
Info : SaveSolution[A] 
Info : (Wall = 40.7256s, CPU = 47.028s, Mem = 4496.32Mb) 
E n d P r o c e s s i n g 
P o s t - P r o c e s s i n g . . . 
Info : NameOfSystem not set in PostProcessing: selected 'A' 
Info : Selected PostProcessing 'MagSta_phi' 
Info : Selected Mesh 'magnet.msh' 
Info : PostOperation 1/4 
> 'res/MagSta_phi_hc.pos' 
Info : PostOperation 2/4 
> 'res/MagSta_phi_phi.pos' 
Info : PostOperation 3/4 
> 'res/MagSta_phi_h.pos' 
Info : PostOperation 4/4 
> 'res/MagSta_phi_b.pos' 
Info : (Wall = 324.758s, CPU = 132.924s, Mem = 4496.32Mb) 
E n d P o s t - P r o c e s s i n g 
Info : Stopped (Wed Aug 9 09:32:31 2017, Wall = 324.946s, CPU = 133.032s, Mem = 4496.32Mb) 

Does any one has clues to explain such a behaviour ? 

Gilles 

	
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