Upgraded Code is slower in runtime as compared to Old code

[Qaiser_Bozdar]

I am upgrading a FORTRAN code that was developed under the domain of Nuclear science.

I have attached txt format Old code and new code and input file to the code. 

My objectives were :

1 To increase capacity of the code so that it computes over large arrays of kind (500,500,500); old code was limited to only (135,135,135) and old code was developed using VISUAL Fortran Professional Edition 5.0A in Microsoft Visual Developer.

2. To increase runtime of code and have a faster convergence (possible to use parallel computing techniques) 

My request to you is that please compile both versions of the code using input file and inform me about the results and convergence time of the code using Intel Fortran Compiler in Visual STUDIO in Windows operating system.

I am facing following issues while achieving my objectives right now.

1. Old code converges within 4 minutes, my upgraded code converges within an hour. 58 mins&53secs

2 There is a difference in the result that is the value of converged K-eff = 1203470 is wrong in my upgraded version.

Please make sure D is input file and it must be in D.INP format.

Actual Results are attached. Actual Results are obtained using old code in a VM box in Win XP.

[jimdempseyatthecove · Accepted solution]

This may or may not be significant:

Old code: ALLOCATE(TMPOWER(153,153,153)) ! 1st element of the array is (1,1,1)

New code: ALLOCATE(TMPOWER(0:500,0:500,0:500)) ! 1st element of the array is (0,0,0)

*** and all the other lower bounds that were 1 and now are 0 ***

Changing the lower bound of each rank from 1 to 0 may be an issue (e.g. you overlooked this in your iteration loop(s)) this may account for results differences.

array(0:500,0:500,0:500) is 51.11 times the size of array(1:135.1:135,1:135) this may account for the runtime difference.

Your runtime difference is 14.75x for 51.11x more data.

Suggestions (leave old code alone, this is your reference):

0) Add IMPLICIT NONE to all your procedures and resolve undeclared variables.

1) change the base of the arrays that are now 0, but were formerly 1, back to 1, run your test

2) that failing, change the upper bound from 500 back to 135, run your test (may need to use old D.INP file)

3) that failing, you may have made an edition error in reformatting the file (removing continuation lines)

4) 2-succeeds, your convergence method may be sensitive to size of data when using 500x500x500. This often occurs when a limit is hand determined using a smaller dataset. Limits should be algorithmically determined at runtime based on size and nature of data.

Additionally, your data is default real(4), with 24 bits of significant. 51x times the data may introduce 51x more error. You might want to consider making your convergence accumulators real(8).

Consider placing the support procedures in a module and declaring the dummy arguments with assumed size notation:

module YourModuleNameHere
 ...
SUBROUTINE PRTCIT(V,NG,ZAF,PD,ISEC1,KSNM,JSNM,ISNM,PHI,TMPOWER ,ALPHALT,ALPHART,ALPHABT,ALPHATP,ALPHABA,ALPHAFR,S,KEFF,M,NOUT,NRST)
  IMPLICIT NONE
  REAL V(:),ZAF(:,:),PD(:),PHI(:,:,:,:),S(:,:,:),KEFF,TMPOWER(:,:,:)
  INTEGER N(:),NG,ISEC1(:),KSNM,JSNM,ISNM,M
  ...
end module YourModuleNameHere
...
Program YourProgramNameHere
  use YourModuleNameHere
  implicit none
  ...
end Program YourProgramNameHere

Then with that change

edit the allocations to use 135 and run the new new code using the old data input.

Jim Dempsey

[Qaiser_Bozdar]

Thank You Sir. You have performed a detailed analysis on my problem. 

I will implement your suggestions and then see what I get.

>> may have made an edition error in reformatting the file (removing continuation lines)

Yes, I had removed continuation lines because they were giving me a format error using Intel Fortran Compiler.

OLD Code eg: REAL SIGMAS(200,5,5),SIGMAA(200,5), NEWSIGMAF(200,5),SIGR(200,5)
* ,BSQ(200,5)

I removed that star and moved BSQ along with upper line. The error was removed.

New Code eg: REAL SIGMAS(200,5,5),SIGMAA(200,5), NEWSIGMAF(200,5),SIGR(200,5) ,BSQ(200,5)

I will report you back when a test your all suggestions.

  Thank You Sir