Case statements switched to if/else for ordering.f90

[kaanolgu]

During the TGV case run I tested for 1000 iterations and AMD uProfiler output showed 10 hottest functions and it turns out to be the reorder_omp is the second highest time consuming function which repeatedly calls the module m_ordering. Before diving deep with algorithmic optimisations I wanted to try something with slight modifications. I noticed that it uses select case for decisions instead of if else. This is not ideal for the compiler. So I modified them to be if/else statement.

Disclaimer would be this change is not necessary for other modules because they are not the first or second hottest functions.

The 1000 TGV run

Before:

 solver instantiated
 initial conditions
 time =   0.0000000000000000      iteration =           0
 enstrophy:  0.37500056314210506     
 div u max mean:   7.4241182236900240E-014   4.6425442329974923E-015
 start run
 time =  0.10000000000000001      iteration =         100
 enstrophy:  0.37525051849886970     
 div u max mean:   1.2185232149686254E-007   3.5138289281208653E-009
 time =  0.20000000000000001      iteration =         200
 enstrophy:  0.37628353027785910     
 div u max mean:   1.2342342865789835E-007   3.5031468385433071E-009
 time =  0.29999999999999999      iteration =         300
 enstrophy:  0.37810777470606399     
 div u max mean:   1.2608932925539662E-007   3.4874846289820097E-009
 time =  0.40000000000000002      iteration =         400
 enstrophy:  0.38073816178863462     
 div u max mean:   1.2987100272976448E-007   3.4683619522790331E-009
 time =  0.50000000000000000      iteration =         500
 enstrophy:  0.38419607045527204     
 div u max mean:   1.3479555077688943E-007   3.4475698888332965E-009
 time =  0.59999999999999998      iteration =         600
 enstrophy:  0.38850900827352475     
 div u max mean:   1.4089259348093464E-007   3.4270327631455799E-009
 time =  0.70000000000000007      iteration =         700
 enstrophy:  0.39371024738962596     
 div u max mean:   1.4818927601689680E-007   3.4086645130049231E-009
 time =  0.80000000000000004      iteration =         800
 enstrophy:  0.39983846518902949     
 div u max mean:   1.5670384551080829E-007   3.3943682946129801E-009
 time =  0.90000000000000002      iteration =         900
 enstrophy:  0.40693741438884812     
 div u max mean:   1.6643768474544629E-007   3.3860065608543613E-009
 time =   1.0000000000000000      iteration =        1000
 enstrophy:  0.41505564012994600     
 div u max mean:   1.7736599844386802E-007   3.3851674985669417E-009
 run end
 Time:    575.58670499999994 

After:

solver instantiated
initial conditions
time =   0.0000000000000000      iteration =           0
enstrophy:  0.37500056314210506     
div u max mean:   7.4241182236900240E-014   4.6425442329974923E-015
start run
time =  0.10000000000000001      iteration =         100
enstrophy:  0.37525051849886970     
div u max mean:   1.2185232149686254E-007   3.5138289281208653E-009
time =  0.20000000000000001      iteration =         200
enstrophy:  0.37628353027785910     
div u max mean:   1.2342342865789835E-007   3.5031468385433071E-009
time =  0.29999999999999999      iteration =         300
enstrophy:  0.37810777470606399     
div u max mean:   1.2608932925539662E-007   3.4874846289820097E-009
time =  0.40000000000000002      iteration =         400
enstrophy:  0.38073816178863462     
div u max mean:   1.2987100272976448E-007   3.4683619522790331E-009
time =  0.50000000000000000      iteration =         500
enstrophy:  0.38419607045527204     
div u max mean:   1.3479555077688943E-007   3.4475698888332965E-009
time =  0.59999999999999998      iteration =         600
enstrophy:  0.38850900827352475     
div u max mean:   1.4089259348093464E-007   3.4270327631455799E-009
time =  0.70000000000000007      iteration =         700
enstrophy:  0.39371024738962596     
div u max mean:   1.4818927601689680E-007   3.4086645130049231E-009
time =  0.80000000000000004      iteration =         800
enstrophy:  0.39983846518902949     
div u max mean:   1.5670384551080829E-007   3.3943682946129801E-009
time =  0.90000000000000002      iteration =         900
enstrophy:  0.40693741438884812     
div u max mean:   1.6643768474544629E-007   3.3860065608543613E-009
time =   1.0000000000000000      iteration =        1000
enstrophy:  0.41505564012994600     
div u max mean:   1.7736599844386802E-007   3.3851674985669417E-009
run end
Time:    564.87784799999997 

Overall, for 20000 case I would expect at least ~3 minute improvement with execution time which is not massive but good small step forward

Compiled with GNU 13.3.0 and OpenMPI 5.0.5, Using 24 MPI Rank and OMP_NUM_THREADS 1 with AMD EPYC 7443 CPU  which is full socket run

[pbartholomew08]

Can you remove, rather than comment, the old code?