[Pw_forum] Questions about parallelization parameters

[mohammed shambakey]

Hi


   1. As I understood from user manual, the “world” of processors is
   devided into number of “images”. Each “image” is devided into number of
   “pools”. Each “pool” is devided into number of “bands”. “PW” level depends
   on the least specified one of the previous four (i.e., if “band” is
   specified, then “PW” is automatically distributed over all processor
   available in each “band”. If “pool” is the least specified parameter, then
   “PW” is automatically distributed over all processors available in each
   “pool”, and so on). Prcoessors of each “PW” is devided into number of
   “tasks” for 3D FFT. “Linear-algebra group” specifies number of processors
   that should not exceed number of processors availabel for each “PW”, right?
   2. Are there guidelines for the best values for the different parameters
   (i.e., ni, nk, nb, ... etc), or I should test each problem individually?
   3. If my understanding is correct, the user manual says “nd is set to 1
   if ScaLAPACK is not compiled, it is set to the square integer smaller than
   or equal to half the number of processors of each pool”. But “nd” should
   not exceed “PW”; and “PW” can be smaller than “half the number of
   processors of each pool” using “nt”. If this case happens, will there be
   error?

Regards

-- 
Mohammed
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