[Wien] wien in parallel mode is slower than serial mode

[nilton@ufba.br]

Dear Stefaan Cottenier
Thank very much for your answer.

> 1) I agree with Florent that it does not make much sense to base
> conclusions on such small jobs. Try something that has at least one
> minute execution time for lapw1.
I did that calculation for one large system (please see below) and the  
results do not changed. As you can see my system have matrix size of  
almost 4000 and the cpu time is almost 16 min to lapw1 what satisfy  
your remark. I am not using mpi because according wien user's guide is  
not necessary to shared memory system(as I said in my first e-mail I  
have core 2 quad system).

.....
> compiled lapw1 with OMP_NUM_TRHEADS=1, while for lapw2 it is 4, and
> you probably run this on a quadcore cpu...? In that case, lapw2 would
> be somewhat parallellized even in a serial run, while lapw1 is not.
I afraid I not get your point. Please, could you tell where I can find  
this variable OMP_NUM_THREADS? I searched in Makefile and in lapw1  
files and don't found it.
regards,
Nilton

Here is the output of my system. As you can see it has the same  
behavior as before, so, to solve my problem I need understand why  
lapw2 spends long time even when compared with serial mode. In  
parallel mode each instance of lapw1 and 2 need work with small number  
of k-points than in serial so that do not make sense lapw2 take more  
time in each operation.

------------------run in parallel mode-----------------------------

:RKM  : MATRIX SIZE 3957LOs: 360  RKM= 8.99  WEIGHT= 1.00  PGR:

running lapw0 in single mode
81.944u 0.645s 0:39.98 206.5%   0+0k 0+7952io 0pf+0w
>   lapw1  -p   (15:30:36) starting parallel lapw1 at Fri Dec 21  
> 15:30:36 BRT 2007
->  starting parallel LAPW1 jobs at Fri Dec 21 15:30:36 BRT 2007
running LAPW1 in parallel mode (using .machines)
4 number_of_parallel_jobs
      localhost(6) 725.214u 2.050s 16:34.90 73.0%        0+0k 0+159168io 0pf+0w
      localhost(6) 684.668u 2.080s 15:57.46 71.7%        0+0k 0+152816io 0pf+0w
      localhost(6) 699.967u 2.097s 16:10.79 72.3%        0+0k 8+153688io 0pf+0w
      localhost(6) 688.346u 1.890s 16:02.18 71.7%        0+0k 8+154800io 0pf+0w
    Summary of lapw1para:
    localhost     k=24    user=2798.2     wallclock=3885.33
2799.483u 9.766s 16:36.02 282.0%        0+0k 16+621200io 0pf+0w
>   lapw2 -p    (15:47:12) running LAPW2 in parallel mode
       localhost 1246.379u 41.656s 19:13.26 111.6% 0+0k 0+11392io 0pf+0w
       localhost 952.876u 34.233s 16:58.17 96.9% 0+0k 0+11392io 0pf+0w
       localhost 552.495u 19.128s 11:48.03 80.7% 0+0k 0+11392io 0pf+0w
       localhost 781.333u 27.519s 15:09.69 88.9% 0+0k 0+11392io 0pf+0w
    Summary of lapw2para:
    localhost     user=3533.08    wallclock=3789.15
3533.914u 122.942s 19:15.69 316.4%      0+0k 8+58696io 0pf+0w
>   lcore       (16:06:28) 0.119u 0.061s 0:00.24 70.8%  0+0k 0+4248io 0pf+0w
>   mixer       (16:06:28) 1.053u 0.180s 0:00.98 125.5% 0+0k 0+14200io 0pf+0w
:ENERGY convergence:  1 0.0001 .0000100000000000
:CHARGE convergence:  0 0.0000 .0005089
ec cc and fc_conv 1 1 1

>   stop


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